JP7576412B2 - Press Equipment - Google Patents

Description

This embodiment relates to a press device that presses an object.

A press device is known that uses a drive device such as a servo motor to move a ram up and down to press an object.

JP 2002-66798 A JP 2008-119737 A

A press device presses an object with a high-pressure load by using a ram. Because the object is pressed with a high-pressure load, the ram receives a reaction force from the object. Although the press device is constructed to be robust, this reaction force causes bending. This bending generally occurs in a direction that separates the ram from the object. For this reason, when the ram is moved a preset travel distance to press the object, the object is undesirably pressed less than the desired amount.

In addition, if the ram is simply moved by a distance equal to the set travel distance plus a preset correction amount to press the object, further deflection occurs in the press device. This further deflection causes the object to be pressed less than the desired amount, which is undesirable.

The deflection that occurs in the press device may differ for each object. In addition, the rigidity of the components that make up the press device may change due to aging or temperature changes, and the deflection that occurs in the press device may differ. There was a problem in that the deflection that occurs in the press device meant that the object could not be pressed accurately.

The present invention has been made to solve the above problems, and aims to provide a press device that can press objects with high precision by reducing deterioration in press precision caused by bending of the press device.

The press device of the present invention is characterized by comprising the following:
(1) A ram that applies load to the object being pressed.
(2) A drive unit that drives the ram.
(3) A detection unit that detects a load value of the load of the ram against the object.
(4) A control unit that controls the drive unit so that the ram applies a load to the object.
(5) The drive unit includes a servo motor.
(6) The control unit controls the rotation amount of the servo motor to move the ram a set movement distance such that the press amount when the object is actually pressed is equal to or less than the desired press amount based on a prior setting, and while the ram is moving the set movement distance, during a delay time due to accumulated pulses that are not allocated to the rotation amount of the servo motor, calculates a shortage movement distance of the ram that is insufficient for the desired press amount based on the load value detected by the detection unit, and controls the rotation amount of the servo motor so that the ram moves the shortage movement distance.

The press device of the present invention may have the following configuration.
(1) The control unit performs control to move the ram the set movement distance and the insufficient movement distance without stopping the ram.
(2) The control unit calculates the amount of deflection caused by the reaction force generated when the load is applied to the object by the ram based on the load value detected by the detection unit, and calculates the missing travel distance based on the calculated amount of deflection.
(3) The control unit calculates the insufficient travel distance based on an amount of change in the load value detected by the detection unit with respect to the travel distance of the ram.
(4) The control unit detects the load value of the ram with respect to the object using the detection unit, calculates the insufficient travel distance, and then performs control to decelerate and move the ram.
(5) The control unit transmits, to the drive unit, a movement command for the set movement distance in several steps, and then transmits a movement command for the insufficient movement distance.

According to the present invention, the drive unit is controlled based on the insufficient travel distance, which is the difference between the set travel distance based on the pre-set settings and the desired pressing amount, so a pressing device that can press an object with high precision can be provided.

According to the present invention, the insufficient travel distance of the ram is calculated based on the load detected by the detection unit, and the drive unit is controlled to move the ram the set travel distance and the insufficient travel distance without stopping it, so the load of the ram can be detected with high precision by the detection unit. This makes it possible to press an object with high precision, regardless of the deflection of the press device, which differs for each object, or changes in deflection that occur in the press device due to aging or temperature changes.

FIG. 1 is a perspective view showing a structure of a press device according to a first embodiment; FIG. 1 is a cross-sectional view showing an inside of a press device according to a first embodiment; FIG. 1 is a block diagram showing a configuration of a press device according to a first embodiment; FIG. 1 is a diagram illustrating deflection of the press device according to the first embodiment; FIG. 13 is a diagram showing a program flow of a calculation unit of the press apparatus according to the first embodiment. FIG. 1 is a diagram illustrating the relationship between the position of the ram and the load of the press device according to the first embodiment; FIG. 13 is a program flow illustrating the deceleration of the ram of the press apparatus according to the first embodiment. FIG. 1 is a diagram for explaining the relationship between the position of the ram and the load when the press apparatus is decelerated according to the first embodiment;

[First embodiment]
[1-1. Schematic configuration]
The configuration of a press machine 1 according to this embodiment will be described below with reference to FIGS.

As shown in Figures 1 to 3, the press device 1 has a control unit 2, a pressure unit 3, a drive unit 4, a detection unit 5, a base 8, and a housing 9. The housing 9 is composed of an enclosure 9a, a support 9b, and a casing 9c. The enclosure 9a, the support 9b, and the casing 9c are made of materials such as aluminum or iron. The enclosure 9a supports the control unit 2, the pressure unit 3, the drive unit 4, and the detection unit 5. The enclosure 9a is fixed to the support 9b, and the support 9b is fixed to the base 8. The base 8 is made of materials such as aluminum or iron, and an object W to be pressed is placed on it.

The pressure applying section 3 has a ram 31 and a ball screw 32.

The ram 31 and ball screw 32 are made of a block of iron material or the like. The ram 31 is formed with a hollow interior. The ram 31 has a female threaded portion 31a inside and is screwed into the ball screw 32. The ball screw 32 is made of a male thread. The ram 31 moves up and down as the ball screw 32 rotates, pressing the object W. In addition, a strain-generating column 31b is provided at the end of the ram 31 that abuts against the object W. The strain-generating column 31b abuts against the object W and applies a load. The ram 31 is housed in a casing 9c and disposed in an enclosure 9a. The ram 31 is guided in its moving direction by a guide portion 6.

The ball screw 32 is connected to the drive unit 4. The ball screw 32 is rotated by being driven by the drive unit 4.

The drive unit 4 has a power transmission unit 41, a servo motor 42, and an encoder 43.

The power transmission unit 41 has a pulley 41a, a belt 41c, and a pulley 41b. The power transmission unit 41 is disposed inside the enclosure 9a. The pulley 41b of the power transmission unit 41 is connected to the ball screw 32. The rotation of the pulley 41a is transmitted to the pulley 41b via the belt 41c, causing the ball screw 32 to rotate. The pulley 41a of the power transmission unit 41 is connected to the servo motor 42.

The servo motor 42 is connected to the control unit 2. The amount of rotation of the servo motor 42 is controlled by the control unit 2. The servo motor 42 rotates the pulley 41a of the power transmission unit 41. The servo motor 42 is disposed inside the enclosure 9a.

The encoder 43 detects the amount of rotation of the servo motor 42. The encoder 43 is connected to the control unit 2. The encoder 43 detects the amount of rotation of the servo motor 42, encodes it, and outputs it to the control unit 2. The encoder 43 is disposed on the servo motor 42.

The detection unit 5 is composed of a strain gauge 51 and a communication unit 52. The strain gauge 51 is composed of a load sensor such as a piezoelectric element. The strain gauge 51 is arranged on the surface opposite the end of the strain-generating column 31b of the ram 31 that abuts against the object W. The strain gauge 51 detects the load of the ram 31 on the object W. The strain gauge 51 transmits an analog signal corresponding to the detected load to the communication unit 52. The analog signal corresponding to the load detected by the strain gauge 51 may be the resistance value of the strain gauge 51.

The communication unit 52 is composed of an analog-to-digital conversion circuit and a transmission circuit. The communication unit 52 is disposed inside the enclosure 9a. The communication unit 52 amplifies the analog signal applied to the load received from the sensor 51, converts it into a digital signal, and transmits it to the control unit 2.

The control unit 2 is mainly composed of a microcomputer. The control unit 2 is disposed inside the enclosure 9a. The control unit 2 controls the pressurizing operation of the pressure unit 3 on the object W. The control unit 2 is connected to the servo motor 42 of the drive unit 4, and controls the amount of rotation of the servo motor 42. The control unit 2 is connected to the encoder 43 of the drive unit 4, and receives the coded amount of rotation of the servo motor 42. The control unit 2 is connected to the communication unit 52 of the detection unit 5, and receives a digital signal applied to the load detected by the sensor 51.

The control unit 2 is composed of a calculation unit 20, a program memory unit 21, a display unit 22, an operation unit 23, a primary memory unit 24, a parameter memory unit 25, a command pulse generation unit 26, a servo motor driver 27, and an encoder position counter 28.

The program storage unit 21 is composed of a memory configured with semiconductors or a storage device such as a hard disk. The program storage unit 21 is connected to the calculation unit 20. The program storage unit 21 stores a program that controls the operation of the calculation unit 20. The calculation unit 20 operates based on the program stored in the program storage unit 21.

The display unit 22 is composed of a plasma display, a liquid crystal display, or the like. The display unit 22 is connected to the calculation unit 20. The display unit 22 is controlled by the calculation unit 20 and displays the set parameters, operating status, etc.

The operation unit 23 is composed of a switch 231 and an input circuit 232. The operation unit 23 is connected to the calculation unit 20. The switch 231 is operated by the operator when starting to press the object W or when stopping the press operation. The operation unit 23 detects that the switch 231 has been operated by the input circuit 232, and outputs the detection result to the calculation unit 20.

The temporary storage unit 24 is composed of a memory made of semiconductors or a storage device such as a hard disk. The temporary storage unit 24 is connected to the calculation unit 20. The temporary storage unit 24 is controlled by the calculation unit 20 and stores temporary data during the calculation process.

The parameter storage unit 25 is composed of a memory made of semiconductors or a storage device such as a hard disk. The parameter storage unit 25 is connected to the calculation unit 20. The parameter storage unit 25 stores a position ZT. The position ZT is a position that is a set movement distance DS in the direction of the base 8 from the position ZS, which is the position where the ram 31 starts to contact the object W. The set movement distance DS is the difference between the position ZS and the position ZT. The set movement distance DS is the movement distance of the ram 31 assuming that no bending occurs in the press device 1. The set movement distance DS is equal to the desired pressing amount DP for pressing the object W.

The position ZT is set by the operator before starting the pressing operation of the object W, and is stored in advance in the parameter storage unit 25. The parameter storage unit 25 may store a preset position ZS and a preset movement distance DS in addition to the position ZT. The parameter storage unit 25 also stores a deflection coefficient K used to calculate the missing movement distance DT. The deflection coefficient K is set in advance by the operator before starting the pressing operation.

The command pulse generating unit 26 is composed of a pulse generating circuit. The command pulse generating unit 26 is connected to the calculation unit 20 and the servo motor driver 27. The command pulse generating unit 26 receives a movement command, which is a command to output a pulse from the calculation unit 20, and converts it into a pulse that controls the amount of rotation of the servo motor 42. The movement command converted into a pulse is input to the servo motor 42 via the servo motor driver 27.

The servo motor driver 27 is composed of a servo motor drive circuit. The servo motor driver 27 is connected to the command pulse generating unit 26 and the servo motor 42. The servo motor driver 27 current-amplifies the pulses related to the movement command converted by the command pulse generating unit 26, and drives the servo motor 42. The servo motor 42 rotates at a rotation angle directly proportional to the number of pulses output from the command pulse generating unit 26. When the servo motor 42 rotates at the desired rotation angle, the ram 31 moves by the desired amount.

The servo motor driver 27 is also connected to the encoder 43 of the drive unit 4 and the calculation unit 20. The servo motor driver 27 receives the rotation angle of the servo motor 42 detected by the encoder 43 and transmits it to the calculation unit 20.

The encoder position counter 28 is composed of a counter circuit. The encoder position counter 28 is connected to the encoder 43 of the drive unit 4 and the calculation unit 20. The encoder position counter 28 receives the coded rotation amount of the servo motor 42 from the encoder 43. The encoder position counter 28 accumulates and counts the rotation amount of the servo motor 42 and transmits it to the calculation unit 20. The calculation unit 20 detects the movement amount and speed of the ram 31 based on the accumulated and counted rotation amount output from the encoder position counter 28.

The calculation unit 20 is composed of a microcomputer. The calculation unit 20 controls the pressure unit 3 via the command pulse generation unit 26, the servo motor driver 27, and the drive unit 4 so as to press the object W with the desired press amount DP. The calculation unit 20 controls the display operation of the display unit 22. The calculation unit 20 also detects operations by the operator via the operation unit 23. The calculation unit 20 controls the storage operation of the primary storage unit 24 and the parameter storage unit 25.

The calculation unit 20 receives the rotation angle of the servo motor 42 detected by the encoder 43 via the servo motor driver 27. The calculation unit 20 also detects the movement amount and speed of the ram 31 based on the cumulatively counted amount of rotation output from the encoder position counter 28. The calculation unit 20 receives a digital signal applied to the load of the ram 31 of the pressure unit 3 from the detection unit 5. The calculation unit 20 operates based on the program stored in the program memory unit 21.

[1-2. Action]
Next, the operation of the press device 1 of this embodiment will be described with reference to Figures 1 to 6. The parameters in this embodiment are as follows.
Desired press amount DP [mm]: The desired press amount DP is the difference in distance between the position where the ram 31 contacts the object W at the start of pressing and the post-processing position of the ram 31 after ideal pressing has been performed, when performing a desired press on the object W. The distance from position XS to position XT, which will be described later, corresponds to the desired press amount DP [mm].
Set travel distance DS [mm]: The set travel distance DS is the distance by which the ram 31 is moved based on the position ZT pre-stored in the parameter storage unit 25. The set travel distance DS is the difference between the position ZS and the position ZT. The set travel distance DS is the travel distance of the ram 31 assuming that no deflection occurs in the press device 1. The set travel distance DS is equal to the desired press amount DP for pressing the object W. Since the ram 31 receives a reaction force from the object W and a deflection amount δ occurs in the press device 1, the pressing of the object W by the set travel distance DS is less than the desired press amount DP.
Shortage travel distance DT [mm]: The shortfall travel distance DT is the difference distance between the desired press amount DP and the set travel distance DS.
Difference R [mm]: The difference R is a distance corresponding to the number of “accumulated pulses” when the servo motor 42 drives the ram 31 .
Deflection amount δ [mm]: The deflection amount δ is a distance corresponding to the deflection generated in the press device 1 due to the reaction force that the ram 31 receives from the object W.
Position ZS [mm]: Position ZS is the position where the ram 31 starts to contact the object W. Position ZS is equal to position XS.
Position Z0 [mm]: Position Z0 is the position where the calculation unit 20 calculates the insufficient travel distance DT.
Position ZT [mm]: Position ZT is a set movement distance DS toward the base 8 from position ZS, which is the position at which the ram 31 starts to contact the target object W. Position ZT is stored in advance in the parameter storage unit 25.
Position XS [mm]: Position XS is the position where the ram 31 actually starts to contact the object W. Position XS is equal to position ZS.
Position XT [mm]: Position XT is the position where pressing of the object W is actually completed. The distance from position XS to position XT is equal to the sum of the set travel distance DS and the insufficient travel distance DT.
Load value F(Z0) [N]: The load value F(Z0) is the load value of the ram 31 at the position Z0.
Load value F(ZT) [N]: The load value F(ZT) is the load value of the ram 31 at the position ZT.
Load value F(XT) [N]: The load value F(XT) is the load value of the ram 31 at the position XT.
Deflection coefficient K [mm/N]: The deflection coefficient K is a proportional coefficient of the load value F [N] to the deflection amount δ.
Load gradient value W(Z0) [N/mm]: The load gradient value W(Z0) is the amount of change in the load value F(Z0) with respect to the travel distance of the ram 31 at the position Z0.
Load gradient value W(ZT) [N/mm]: The load gradient value W(ZT) is the amount of change in the load value F(ZT) with respect to the travel distance of the ram 31 at the position ZT.
Load gradient value W(XT) [N/mm]: The load gradient value W(XT) is the amount of change in the load value F(XT) with respect to the travel distance of the ram 31 at the position XT.
Movement speed V [mm/S]: The movement speed V is the movement speed of the ram 31.
Coefficient SV[S]: The coefficient SV is an overshoot distance coefficient.

[Operation of Calculation Unit 20]
The calculation unit 20 of the control unit 2 controls the pressurizing unit 3 via the command pulse generating unit 26, the servo motor driver 27, and the drive unit 4, and presses the object W. The calculation unit 20 detects an operation by the operator indicating the start of pressing by the operation unit 23, and controls the operation of pressing the object W.

The ram 31 of the pressure unit 3 moves based on the movement command sent to the calculation unit 20, and the object W is pressed. First, the calculation unit 20 controls the movement of the ram 31 to press the object W by a set movement distance DS based on a position ZT previously set in the parameter storage unit 25.

The press device 1 presses the object W with a high-pressure load using the ram 31. Because the object W is pressed with a high-pressure load, the ram 31 receives a reaction force from the object W. The press device 1 is constructed to be robust, but as shown in FIG. 4, this reaction force causes a deflection of a deflection amount δ. This deflection generally occurs in a direction that separates the ram 31 and the object W.

Therefore, when the ram 31 is moved a set movement distance DS based on a preset position ZT and the object W is pressed, the object W will be pressed less than the desired press amount DP.

It is also possible to simply store the shortfall in travel distance DT in the parameter storage unit 25 as a correction amount, add the previously set shortfall in travel distance DT to the set travel distance DS, and move the ram 31. However, if the object is pressed further due to the shortfall in travel distance DT, further deflection will occur in the press device 1.

When the ram 31 is moved by the shortfall travel distance DT, the reaction force that the ram 31 receives from the object W is greater than the reaction force that the ram 31 receives when the ram 31 is moved by the set travel distance DS. Therefore, the amount of deflection δ that generally occurs in the press device 1 is greater when pressing by the shortfall travel distance DT than when pressing by the set travel distance DS due to further deflection. If the ram 31 is moved by the previously set shortfall travel distance DT in addition to the set travel distance DS, the object will be pressed less than the desired press amount DP due to this further deflection, which is undesirable.

The calculation unit 20 of the control unit 2 calculates a set travel distance DS based on a preset position ZT, and a shortage travel distance DT, which is the difference between the desired press amount DP and the set travel distance DS. The calculation unit 20 controls the drive unit 4 based on the shortage travel distance DT, and operates the pressure unit 3. The calculation unit 20 calculates the shortage travel distance DT based on the load detected by the detection unit 5, and moves the ram 31 a distance equal to the set travel distance DS and the shortage travel distance DT without stopping it.

The calculation unit 20 of the control unit 2 calculates the deflection amount δ caused by the reaction force generated when the load is applied to the object W by the ram 31 based on the load value F detected by the detection unit 5, and calculates the missing travel distance DT based on the calculated deflection amount δ.

The calculation unit 20 of the control unit 2 calculates the missing travel distance DT based on the load gradient value W, which is the amount of change in the load value F detected by the detection unit 5 relative to the travel distance of the ram 31.

The calculation unit 20 of the control unit 2 transmits a movement command for the set movement distance DS in several steps to the drive unit 4, and then transmits a movement command for the insufficient movement distance DT.

The calculation unit 20 of the control unit 2 performs the following operations according to the program shown in FIG. 5 stored in the program storage unit 21.

First, the calculation unit 20 detects that the switch 231 of the operation unit 23 has been pressed and starts processing (step S01). When starting a press operation, the operator presses the switch 231 to instruct the start of the press operation.

Next, the calculation unit 20 reads out the position ZT stored in the parameter storage unit 25 (step S02). The target stop position of the ram 31 at the end of pressing is determined by the position ZT. The position ZT is a position that is a set movement distance DS in the direction of the base 8 from the position ZS, which is the position where the ram 31 starts to contact the object W. The set movement distance DS is the difference between the position ZS and the position ZT. The set movement distance DS is the movement distance of the ram 31 assuming that no bending occurs in the press device 1. The set movement distance DS is equal to the desired pressing amount DP for pressing the object W.

Next, the calculation unit 20 sends a movement command to the command pulse generation unit 26 (step S03). The calculation unit 20 uses the movement command to move the ram 31 from position ZS to position ZT, which is the set movement distance DS. The movement command converted into pulses by the command pulse generation unit 26 is input to the servo motor 42 via the servo motor driver 27. This causes the servo motor 42 to start rotating. The rotation of the servo motor 42 is transmitted via the power transmission unit 41 to rotate the ball screw 32, and the ram 31 moves.

The servo motor 42 rotates at a rotation angle directly proportional to the number of pulses output from the command pulse generating unit 26. First, the ram 31 is moved to position ZS. At this point, the ram 31 is not receiving a reaction force, so position ZS is equal to position XS, which is the position where the ram 31 actually starts to contact the object W.

Then, the calculation unit 20 transmits a movement command equivalent to the set movement distance DS to the command pulse generation unit 26 in several steps. For example, if the servo motor 42 moves a distance equivalent to the set movement distance DS with 10,000 pulses, the calculation unit 20 transmits a movement command to the command pulse generation unit 26 in 1000 steps so that 10 pulses are output from the command pulse generation unit 26 every 1 ms.

Then, the calculation unit 20 judges whether the ram 31 has reached position Z0 (step S04). At position Z0, the calculation unit 20 calculates the insufficient travel distance DT. Position Z0 is the position before the ram 31 moves the insufficient travel distance DT and before it finishes moving the set travel distance DS. The position of the ram 31 is judged based on the cumulative amount of rotation of the servo motor 42, which is cumulatively counted by the encoder position counter 28.

If it is not determined that the ram 31 has reached position Z0, the calculation unit 20 repeats the operation of step S03. If it is determined that the ram 31 has reached position Z0, the calculation unit 20 performs the operation of step S05.

When it is determined that the ram 31 has reached position Z0, the calculation unit 20 receives the load value F(Z0) at position Z0 (step S05). The load value F(Z0) is detected by the detection unit 5 and transmitted to the control unit 2. Figure 6 shows a graph showing the relationship between the position of the ram 31 and the load value F(Z0).

Next, the calculation unit 20 calculates the load gradient value W(Z0) (step S06). The load gradient value W(Z0) is calculated based on the load value F(Z0) received in step S05. The load gradient value W(Z0) is the amount of change in the load value F(Z0) with respect to the travel distance of the ram 31. The load gradient value W(Z0) corresponds to the differential value of the load value F(Z0) at the position Z0 of the ram 31. The method of calculating the load gradient value W(Z0) will be described later.

Next, the calculation unit 20 calculates the insufficient travel distance DT (step S07). The insufficient travel distance DT is calculated based on the load value F(Z0) detected by the detection unit 5, by calculating the amount of deflection δ applied to the deflection caused by the reaction force generated when the load is applied to the object W by the ram 31, and the calculated amount of deflection δ. The insufficient travel distance DT is also calculated based on the load gradient value W(Z0), which is the amount of change in the load value F(Z0) detected by the detection unit 5 relative to the travel distance of the ram 31. The load gradient value W(Z0) is calculated in step S06. The method of calculating the insufficient travel distance DT will be described later.

After reaching position Z0, the ram 31 is moved to position ZT while the calculation unit 20 is calculating the missing travel distance DT. The object W is pressed a distance of the set travel distance DS from position XS to position ZT. The set travel distance DS is less than the desired pressing amount DP.

The calculation unit 20 then transmits a movement command for the insufficient travel distance DT to the command pulse generation unit 26 (step S08). The command pulse generation unit 26 generates pulses that control the amount of rotation of the servo motor 42 for the insufficient travel distance DT. The generated pulses are input to the servo motor 42 via the servo motor driver 27. This causes the servo motor 42 to rotate. The rotation of the servo motor 42 is transmitted to the power transmission unit 41 and the ball screw 32, and the ram 31 moves the insufficient travel distance DT.

As a result, the ram 31 is moved to position XT. The object W is pressed the distance from position XS to position XT. The distance from position XS to position XT is equal to the desired press amount DP. As a result, the object W is pressed by the desired press amount DP.

Then, the calculation unit 20 stops the press operation.

[Calculation of insufficient travel distance DT by calculation unit 20]
Next, the calculation of the insufficient travel distance DT by the calculation unit 20 will be described. Since the press device 1 presses the object with a high load by the ram 31, the ram 31 receives a reaction force from the object W. As shown in FIG. 4, this reaction force causes the press device 1 to bend by a bending amount δ. This bending generally occurs in a direction that separates the ram 31 and the object W. For this reason, when the ram 31 is moved by the set travel distance DS to press the object W, the object W will be pressed by less than the desired pressing amount DP.

In addition, if the ram 31 is simply moved by an amount equal to the set movement distance DS plus a preset correction amount to press the object W, further deflection occurs in the press device 1. Due to this further deflection, the object W will be pressed less than the desired press amount DP.

The further deflection that occurs in the press device 1 may differ for each object W. In addition, the rigidity of the components that make up the press device 1 may change due to aging or temperature changes, and the deflection that occurs in the press device 1 may differ.

To solve this problem, the calculation unit 20 calculates the amount of deflection δ that occurs in the press device 1 for each object W individually, and calculates the missing travel distance DT based on the calculated amount of deflection δ.

The ram 31 receives a reaction force from the object W, and the enclosure 9a and the support 9b of the press device 1 are deflected relative to the base 8. This deflection causes the ram 31 to move away from the base 8. As a result, the object W is pressed with a distance corresponding to the deflection amount δ short of the desired press amount DP.

The amount of deflection δ generated in the press device 1 is directly proportional to the load value F [N] applied to the ram 31. The relationship between the amount of deflection δ [mm] and the load value F [N] is expressed by (Equation 1).
δ[mm]=K[mm/N]*F[N]
.... (Equation 1)
In formula 1, K [mm/N] is the deflection coefficient, which is a proportional coefficient of the load value F [N] to the deflection amount δ.

The deflection coefficient K [mm/N] is preset and stored in the parameter storage unit 25. The deflection coefficient K [mm/N] is calculated by lowering the ram 31 with a length measuring device attached to measure the distance between the tip of the ram 31 and the base 8, and measuring the load value F [N] applied to the ram 31 and the amount of deflection δ [mm] in advance.

The deflection coefficient K [mm/N] may be a single value for all sections in the travel distance of the ram 31. The deflection coefficient K [mm/N] may also be a different value for each section in the travel distance of the ram 31. The deflection coefficient K [mm/N] is not necessarily constant for all sections in the travel distance of the ram 31. The deflection coefficient K [mm/N] may be expressed, for example, by broken line approximation for each section in the travel distance of the ram 31. The sections in the travel distance of the ram 31 may be divided into N sections, and the coefficient of the i-th section may be the deflection coefficient Ki [mm/N] (i = 1 to N).

The relationship between the position Z [mm] of the ram 31 when it is assumed that no deflection occurs in the press device 1 and the position X [mm] of the ram 31 when deflection occurs in the press device 1 when pressing the object W is expressed by (Equation 2).
X [mm] = Z [mm] + δ [mm]
....(Equation 2)
In (Equation 2), δ [mm] is the amount of deflection δ [mm] in (Equation 1) described above.

In FIG. 6, the position to which the ram 31 is moved by a set movement distance DS based on a preset position ZT is represented by Z, and the actual position of the ram 31 when bending occurs in the press device 1 is represented by X. The position at which the ram 31 starts to contact the object W is represented by position ZS or position XS, and the position of the ram 31 at the time when pressing of the object W is completed is represented by XT.

The distance from position ZS to position ZT when no bending occurs in the press device 1 is the set travel distance DS. The set travel distance DS is equal to the desired press amount DP.

When there is deflection, the distance from position XS to position XT is equal to the desired press amount DP. The desired press amount DP is equivalent to the sum of the set travel distance DS and the insufficient travel distance DT. Positions ZS and XS are the same position where the ram 31 begins to contact the object W.

The calculation unit 20 transmits a movement command equivalent to the set movement distance DS in several steps to the command pulse generation unit 26 in order to move the ram 31. The servo motor 42 rotates at a rotation angle directly proportional to the number of pulses output from the command pulse generation unit 26. The servo motor 42 starts rotating based on the number of pulses output from the command pulse generation unit 26.

However, after multiple pulses are output from the command pulse generating unit 26, a time delay occurs before the rotation of the servo motor 42 reaches the commanded amount of rotation. Among the multiple pulses output from the command pulse generating unit 26, the pulses that are not allocated to the amount of rotation of the servo motor 42 due to this time delay are called "accumulated pulses."

The calculation unit 20 sends a movement command to the command pulse generation unit 26. The command pulse generation unit 26 converts the movement command into a pulse, and outputs a command pulse having a quantity for moving to position ZT to the servo motor 42 (corresponding to step S03). The calculation unit 20 sends a movement command equivalent to the set movement distance DS so that the command pulse generation unit 26 outputs command pulses in several stages. If it is assumed that no deflection occurs in the press device 1, the position XT of the ram 31 is ZT, and there is no need to calculate the amount of deflection δ [mm] using (Equation 1).

However, bending occurs in the press device 1 during pressing. When bending occurs in the press device 1, the calculation is performed as follows.

First, the calculation unit 20 controls the ram 31 to move the set movement distance DS on the assumption that no bending occurs in the press device 1. That is, the calculation unit 20 sends a movement command to the command pulse generation unit 26 to move the ram 31 from position ZS to position ZT. The command pulse generation unit 26 converts the movement command into a pulse having a quantity for moving the ram 31 to position ZT, and outputs it to the servo motor 42.

The calculation unit 20 transmits a movement command to move the ram 31 to position ZT to the command pulse generating unit 26 in several steps (step S03). The calculation unit 20 also receives the load value F(Z0) at this time from the detection unit 5 (step S05). The calculation unit 20 calculates the load gradient value W(Z0) based on the load value F(Z0) (step S06).

Then, the calculation unit 20 calculates the insufficient travel distance DT (step S07). The insufficient travel distance DT is calculated at a time after the ram 31 reaches position Z0 and before it reaches position ZT.

The position Z0 is detected by calculating the amount of movement of the ram 31 by the calculation unit 20 based on the cumulative rotation amount of the servo motor 42 output from the encoder position counter 28. The load value F(Z0) is an analog signal of the load of the ram 31 on the object W detected by the strain gauge 51, which is converted into a digital signal by the communication unit 52 and input to the calculation unit 20.

The load gradient value W is the increase in the load value F per unit distance, and has the same dimension [N/mm] as the spring constant. The load gradient value W is the derivative of the load value F with respect to the position, and is expressed by (Equation 3).
W [N/mm] = dF [N]/dZ [mm]
....(Equation 3)

The load gradient value W [N/mm] is the gradient in the graph shown in Figure 6, with the horizontal axis representing the position Z [mm] and the vertical axis representing the load value F [N].

・・・・・（式４） In order to reduce the influence of variations and to calculate a highly reliable slope value, it is preferable to calculate the slope of the graph by linear regression calculation. When data indicating the position Z [mm] of the tip of the ram 31 is (Z1, Z2, ... Zn) and data indicating the position Z [mm] load value F [N] at each position is (F1, F2, ... Fn), a regression line is drawn for each point. The slope of the regression line is expressed by (Equation 4).

....(Equation 4)

The calculation unit 20 calculates the load gradient value W(Z0) [N/mm] based on n sets of data up to the position Z0 [mm] using (Equation 4).

The calculation unit 20 calculates the difference R [mm] between the position Z0 [mm] of the ram 31 at the time when all the movement commands related to the set movement distance DS, which are output in several stages, have been transmitted, and the position ZT [mm], which is the target position to which the ram 31 is assumed to move in response to all the movement commands related to the set movement distance DS. The difference R [mm] is expressed by (Equation 5).
ZT [mm] = Z0 [mm] + R [mm]
....(Equation 5)

The difference R [mm] corresponds to the number of "accumulated pulses" when the servo motor 42 drives the ram 31. The number of "accumulated pulses" is directly proportional to the moving speed V [mm/S] of the ram 31. The relationship between the difference R [mm] and the moving speed V [mm/S] of the ram 31 is expressed by (Equation 6).
R [mm] = SV [S] * V [mm/S]
....(Equation 6)
In equation (6), SV[S] is a coefficient.

The coefficient SV[S] varies depending on the configuration of the drive unit 4 and pressure unit 3, the feedback gain of the servo motor driver 27, etc. The coefficient SV[S] is calculated in advance and stored in the parameter storage unit 25. The coefficient SV[S] is calculated by inputting a pulse to the servo motor 42 to change the moving speed V[mm/S] of the ram 31, measuring the moving distance of the ram 31 from the point when the input of the pulse is stopped until the movement of the ram 31 stops, and measuring the slope of the measured moving distance of the ram 31.

Assuming that the load gradient value W [N/mm] does not change even when the ram 31 moves a small distance R [mm], the load gradient value W(ZT) [N/mm] at position ZT [mm] is expressed by (Equation 7).
W (ZT) [N/mm] = W (Z0+R) [N/mm] = W (Z0) [N/mm]
....(Equation 7)

After calculating the shortfall in travel distance DT, the calculation unit 20 sends a movement command for the shortfall in travel distance DT to the command pulse generation unit 26, which converts it into a pulse (step S08). The command pulse generation unit 26 outputs a pulse that controls the amount of rotation of the servo motor 42. This causes the ram 31 to move a distance equivalent to the shortfall in travel distance DT. The calculation unit 20 controls the movement of the ram 31 to the target position XT.

The calculation unit 20 calculates the insufficient travel distance DT as follows. The difference between the position Z0 [mm] and the target position, that is, the position XT, is minute. Therefore, if it is assumed that the load gradient value W(XT) [N/mm] at the position XT [mm] is the same as the load gradient value W(ZT) [N/mm] at the position ZT [mm], the load gradient value W(XT) [N/mm] at the position XT [mm] is expressed by (Equation 8).
W (XT) [N/mm] = W (ZT+DT) [N/mm]
=W(ZT)[N/mm]=W(Z0+R)[N/mm]=W(Z0)[N/mm]
....(Equation 8)

By modifying (Equation 3), the increase dF of the load value F per unit distance is expressed by (Equation 9).
dF[N]=W[N/mm]*dZ[mm]
....(Equation 9)

From the above, the load value F(XT) at the position XT, which is the target position, is the load value F(ZT+DT), and is therefore expressed by (Equation 10). Moreover, the load value F(XT) with respect to the position XT is shown in FIG.
F(XT)[N]=F(Z0+R+DT)
=F(Z0)[N]+W(Z0)[N/mm]*R[mm]
+W (Z0) [N/mm] *DT [mm]
...(Formula 10)

In Figure 6, the gradient between positions ZS and Z0 is the load gradient value W0 [N/mm], the gradient between positions Z0 and ZT is the load gradient value W1 [N/mm], and the gradient between positions ZT and XT is the load gradient value W2 [N/mm].

The change in load ΔF (Z0→ZT) between position Z0 and position ZT is as shown in (Equation 100).
ΔF (Z0 → ZT) [N] = W1 [N/mm] * R [mm]
...(Formula 100)

Similarly, the change in load ΔF (ZT→XT) between position ZT and position XT is as shown in (Equation 101).
ΔF (ZT → XT) [N] = W2 [N/mm] * DT [mm]
...(Formula 101)

Therefore, F(XT) is as shown in (Equation 102).
F(XT)[N]=F(Z0)[N]+ΔF(Z0→ZT)[N]
+ΔF (ZT→XT) [N]
...(Formula 102)

Substituting (Equation 100) and (Equation 101), (Equation 102) becomes as shown in (Equation 103).
F(XT)[N]=F(Z0)[N]+W1[N/mm]*R[mm]
+W2 [N/mm] * DT [mm]
...(Formula 103)

Since the difference R [mm] and the insufficient travel distance DT [mm] are minute, the load gradient values W1 [N/mm] and W2 [N/mm] are as shown by the approximation formulas (Equation 104) and (Equation 105).
W1 [N/mm] = W0 [N/mm]
...(Formula 104)
W2 [N/mm] = W0 [N/mm]
...(Formula 105)

Substituting (Equation 104) and (Equation 105), (Equation 103) becomes as shown in (Equation 106).
F(XT)[N]=F(Z0)[N]+W0[N/mm]*R[mm]
+W0[N/mm]*DT[mm]
...(Formula 106)

Since the load gradient value W0 [N/mm] is the load gradient value W1 [N/mm] at the position Z0 [mm], (Equation 106) becomes (Equation 10).
F(XT)[N]=F(Z0)[N]+W(Z0)[N/mm]*R[mm]
+W (Z0) [N/mm] *DT [mm]
...(Formula 10)

The insufficient travel distance DT is the amount of deflection at the position XT which is the final target position, and is expressed by (Equation 11).
DT [mm] = K [mm/N] * F (XT) [N]
...(Formula 11)

By substituting (Equation 10) into the right-hand side of (Equation 11), the insufficient movement distance DT is expressed by (Equation 12).
DT [mm] = K [mm/N] * F (Z0) [N]
+K[mm/N]*W(Z0)[N/mm]*R[mm]
+K[mm/N]*W(Z0)[N/mm]*DT[mm]
...(Formula 12)

・・・・・（式１３）
ここで、Ｆ（Ｚ０）［Ｎ］、Ｋ［ｍｍ／Ｎ］、Ｗ（Ｚ０）［Ｎ／ｍｍ］、ＳＶ［Ｓ］、Ｖ［ｍｍ／Ｓ］は、測定または算出により上記の通り既知であり、演算部２０は、（式１３）に基づき不足移動距離ＤＴの算出を行う。 Based on (Equation 12) and (Equation 6), the insufficient movement distance DT is expressed by (Equation 13).

...(Formula 13)
Here, F(Z0) [N], K [mm/N], W(Z0) [N/mm], SV [S], and V [mm/S] are known by measurement or calculation as described above, and the calculation unit 20 calculates the insufficient travel distance DT based on (Equation 13).

When the ram 31 reaches position Z0, the calculation unit 20 calculates the insufficient travel distance DT and transmits a travel command for the insufficient travel distance DT to the command pulse generation unit 26. Position Z0 is the position before the ram 31 reaches position ZT, which is the position that satisfies the set travel distance DS. Position Z0 is separated from position ZT by a distance equivalent to the difference R [mm].

At the point when the ram 31 reaches position Z0, the servo motor 42 has a "accumulated pulse" equivalent to the difference R [mm]. A time delay occurs before the rotation of the servo motor 42 reaches an amount of rotation equivalent to the "accumulated pulse." During this delay, the calculation unit 20 calculates the missing travel distance DT before the ram 31 reaches position ZT.

If the movement of the set travel distance DS and the shortfall travel distance DT were performed with the ram 31 stopped once, the load value F(Z0) on the ram 31 would fluctuate significantly, making it impossible to accurately calculate the shortfall travel distance DT. The calculation unit 20 calculates the shortfall travel distance DT before the ram 31 reaches position ZT, and moves the distance of the set travel distance DS and the shortfall travel distance DT without stopping the ram 31.

[Operation of the calculation unit 20 with deceleration of the ram 31]
The calculation unit 20 may perform the movement corresponding to the insufficient movement distance DT by decelerating or accelerating the ram 31 without stopping the ram 31.

When moving the ram 31 at a constant speed, the calculation unit 20 sends a movement command to the command pulse generating unit 26 at regular time intervals, and the servo motor 42 rotates at a rotation angle directly proportional to the number of pulses output from the command pulse generating unit 26. For example, when the movement speed of the ram 31 is high, the time to calculate the insufficient movement distance DT is insufficient, and the calculation unit 20 may be delayed in sending a movement command for the insufficient movement distance DT to the command pulse generating unit 26, which may result in the movement of the ram 31 being stopped.

The load value F(Z0) varies depending on the movement speed of the ram 31. If the load value F(Z0) applied to the ram 31 is measured after the movement of the ram 31 is decelerated, the value of the load value F(Z0) fluctuates and the load value F(Z0) cannot be detected accurately. As a result, the insufficient travel distance DT cannot be calculated accurately, which is undesirable. When it is predicted that there will be insufficient time to calculate the insufficient travel distance DT and it is necessary to decelerate the movement speed of the ram 31, the calculation unit 20 may calculate the insufficient travel distance DT before decelerating the movement of the ram 31.

In addition, after a movement command is sent from the calculation unit 20, a time delay occurs until the ram 31 completes the movement in response to the movement command. This time delay is unavoidable, particularly when the drive unit 4 is configured to include a servo motor 42. For example, the time it takes for the amount of rotation of the servo motor 42 to reach an amount of rotation equivalent to the "accumulated pulse" corresponds to this time delay. The distance between position ZT, which is the target position to which the set movement distance DS is moved, and position Z0 of the ram 31 at the time the movement command is sent, is the distance caused by the "accumulated pulse", and is the difference R shown in the above-mentioned (Equation 5).

When the difference R is large, the distance between the target position ZT and the position Z0 of the ram 31 at the time the movement command is sent becomes large, and the missing travel distance DT cannot be calculated accurately, which is undesirable. The difference R is directly proportional to the movement speed V of the ram 31 as shown in (Equation 6). Therefore, by slowing down the movement speed V of the ram 31, the difference R can be reduced and the calculation accuracy of the missing travel distance DT can be improved. Even when the movement speed of the ram 31 is slowed down in order to improve the calculation accuracy of the missing travel distance DT, the calculation unit 20 may calculate the missing travel distance DT before slowing down the movement of the ram 31.

The calculation unit 20 detects the load value F(ZE) of the ram 31 on the object W at position ZE before the ram 31 reaches position Z0 using the detection unit 5, and calculates the insufficient travel distance DT. Position ZE is a position that is a travel distance Q [mm] away from the base 8 from position Z0. Thereafter, the calculation unit 20 performs control to decelerate the movement of the ram 31. To decelerate the movement of the ram 31, the calculation unit 20 increases the time interval for sending a movement command to the command pulse generation unit 26.

As described above, when the movement of the ram 31 is decelerated at the position ZE, the insufficient movement distance DT is calculated by (Equation 14) instead of (Equation 10).
F(XT)[N]=F(ZE+Q+R+DT)
=F(ZE)[N]+W(ZE)[N/mm]*Q[mm]
W (ZE) [N/mm] * R [mm] + W (ZE) [N/mm] * DT [mm]
...(Formula 14)
The movement distance Q [mm] is the distance between the position ZE and the position Z0.

・・・・・（式１５）
ここで、Ｆ（ＺＥ）［Ｎ］、Ｋ［ｍｍ／Ｎ］、Ｗ（ＺＥ）［Ｎ／ｍｍ］、Ｑ［ｍｍ］、ＳＶ［Ｓ］、Ｖ［ｍｍ／Ｓ］は、測定または算出により上記の通り既知であり、演算部２０は、（式１５）に基づき不足移動距離ＤＴの算出を行う。 Moreover, the insufficient movement distance DT is expressed by (Equation 15) instead of (Equation 13).

...(Formula 15)
Here, F(ZE) [N], K [mm/N], W(ZE) [N/mm], Q [mm], SV [S], and V [mm/S] are known by measurement or calculation as described above, and the calculation unit 20 calculates the insufficient travel distance DT based on (Equation 15).

The calculation unit 20 of the control unit 2 performs an operation involving deceleration of the movement of the ram 31 according to the program shown in FIG. 7 stored in the program memory unit 21.

First, the calculation unit 20 detects that the switch 231 of the operation unit 23 has been pressed and starts processing (step S11). When the press operation is to start, the operator presses the switch 231 to indicate the start of the press operation.

Then, the calculation unit 20 reads out the position ZT stored in the parameter storage unit 25 (step S12). The target stop position of the ram 31 at the end of pressing is determined by the position ZT. The position ZT is a position that is a set movement distance DS from the position ZS toward the base 8. The set movement distance DS is the movement distance of the ram 31 assuming that no bending occurs in the press device 1.

Next, the calculation unit 20 transmits a movement command to the command pulse generating unit 26 (step S13). In response to the movement command, the calculation unit 20 moves the ram 31 from position ZS to position ZT, which is the set movement distance DS.

The servo motor 42 rotates at a rotation angle directly proportional to the number of pulses output from the command pulse generating unit 26. The calculation unit 20 transmits a movement command corresponding to the set movement distance DS to the command pulse generating unit 26 in several steps.

The calculation unit 20 then determines whether the ram 31 has reached position ZE (step S14). At position ZE, the detection unit 5 detects the load value F(ZE) of the ram 31 on the object W, calculates the insufficient travel distance DT, and controls the ram 31 to decelerate. Position ZE is the position before the ram 31 moves the insufficient travel distance DT and before it finishes moving the set travel distance DS. The position of the ram 31 is determined based on the cumulative amount of rotation of the servo motor 42, which is cumulatively counted by the encoder position counter 28.

If it is not determined that the ram 31 has reached position ZE, the calculation unit 20 repeats the operation of step S13. If it is determined that the ram 31 has reached position ZE, the calculation unit 20 performs the operation of step S15.

When it is determined that the ram 31 has reached the position ZE, the calculation unit 20 receives the load value F(ZE) at the position ZE (step S15). Figure 8 shows a graph showing the relationship between the position of the ram 31 and the load value F(ZE).

Next, the calculation unit 20 calculates the load gradient value W(ZE) (step S16). The load gradient value W(ZE) is calculated using (Equation 4) based on the load value F(ZE) received in step S05. The load gradient value W(ZE) is the amount of change in the load value F(ZE) with respect to the travel distance of the ram 31. The load gradient value W(ZE) corresponds to the differential value of the load value F(ZE) at the position ZE of the ram 31.

Next, the calculation unit 20 calculates the insufficient travel distance DT (step S17). The insufficient travel distance DT is calculated using the above (Equation 15).

Next, the calculation unit 20 transmits a movement command for the insufficient movement distance DT to the command pulse generation unit 26 (step S18). The servo motor 42 receives the movement command converted into pulses from the command pulse generation unit 26. This causes the servo motor 42 to rotate, and the ram 31 moves the insufficient movement distance DT.

The calculation unit 20 transmits a movement command to the command pulse generation unit 26 to decelerate and move the ram 31 (step S19). As a result, the ram 31 moves at a reduced speed the movement distance Q in the set movement distance DS. The calculation unit 20 may control the ram 31 so that after the ram 31 has decelerated and moved the movement distance Q, it moves at the speed before it reached the position ZE.

As a result, the ram 31 is moved to position XT. The object W is pressed the distance from position XS to position XT. The distance from position XS to position XT is equal to the desired press amount DP. As a result, the object W is pressed by the desired press amount DP.

Then, the calculation unit 20 stops the press operation.

The above is the function of the press device 1.

[1-3. Effects]
(1) According to the present invention, the press apparatus 1 includes a ram 31 that applies a load to an object W to be pressed, a drive unit 4 that drives the ram 31, a detection unit 5 that detects a load value F(Z0) of the load of the ram 31 on the object W, and a control unit 2 that controls the drive unit 4 so that the ram 31 applies a load to the object W. The control unit 2 controls the ram 31 to move a set movement distance DS based on a prior setting so that the press amount when the object W is actually pressed is equal to or less than a desired press amount DP, and while the ram 31 is moving the set movement distance DS, a shortfall movement distance DT of the ram 31 that is short of the desired press amount DP is calculated based on the load value F(Z0) detected by the detection unit 5, and controls the ram 31 to move the shortfall movement distance DT. This makes it possible to provide a press apparatus 1 that can press the object W with high precision.

While the ram 31 is moving the set travel distance DS, the load value F(Z0) of the ram 31 is detected by the detection unit 5, so the load value F(Z0) of the load of the ram 31 is detected with high precision. This allows the insufficient travel distance DT to be calculated with high precision, and as a result, the object W can be pressed with high precision.

(2) According to the present invention, the control unit 2 of the press device 1 controls the ram 31 to move the set travel distance DS and the insufficient travel distance DT without stopping the ram 31, so that a press device 1 can be provided that can press the object W with high precision.

If the movement of the set travel distance DS and the shortage travel distance DT were performed with the ram 31 stopped once, the load value F (Z0) on the ram 31 would fluctuate significantly, making it impossible to accurately calculate the shortage travel distance DT. According to the present invention, the control unit 2 moves the set travel distance DS and the shortage travel distance DT without stopping the ram 31, thereby suppressing fluctuations in the load value F (Z0) on the ram 31. This allows the shortage travel distance DT to be calculated with high accuracy. As a result, the object can be pressed with high accuracy regardless of the deflection that occurs in the press device 1.

In addition, if the ram 31 is stopped once, there is a possibility that the press processing results of the object W may be affected due to press-fitting, etc. In addition, if the ram 31 is stopped once, there is a disadvantage that the processing time per object W becomes longer than when the ram 31 is not stopped once. As a result, there is a disadvantage that the number of objects W that can be press-processed per unit time becomes smaller.

According to the present invention, the control unit 2 moves the set travel distance DS and the insufficient travel distance DT without stopping the ram 31, so that the influence on the press processing results of the object W caused by press-fitting, etc. can be reduced. In addition, according to the present invention, the processing time per object W can be shortened compared to when the ram 31 is not stopped once, and as a result, the number of objects W that can be press processed per unit time can be increased.

(3) According to the present invention, the control unit 2 calculates the deflection amount δ due to the deflection caused by the reaction force generated when the load is applied to the object W by the ram 31 based on the load value F (Z0) detected by the detection unit 5, and calculates the missing travel distance DT based on the calculated deflection amount δ, thereby providing a press device 1 that can press the object W with high accuracy.

The amount of deflection δ that occurs in the press device 1 may differ for each object W. In addition, the rigidity of the components that make up the press device 1 may change due to aging or temperature changes, and the deflection that occurs in the press device 1 may differ. The control unit 2 calculates the amount of deflection δ that occurs in the press device 1 based on the load value F (Z0) detected by the detection unit 5, and calculates the missing travel distance DT based on the amount of deflection δ.

According to the present invention, the control unit 2 calculates the deflection amount δ for each object W based on the load value F (Z0) detected by the detection unit 5, and calculates the missing travel distance DT based on the calculated deflection amount δ, so that the object W can be pressed with high accuracy.

(4) According to the present invention, the control unit 2 calculates the insufficient travel distance DT based on the amount of change in the load value F (Z0) detected by the detection unit 5 relative to the travel distance of the ram 31, so that a press device 1 can be provided that can press the object W with high accuracy.

The control unit 2 predicts the load value F(XT) at the position XT of the ram 31 when pressing is completed based on the amount of change in the load value F(Z0) relative to the travel distance of the ram 31, and calculates the insufficient travel distance DT. This allows the insufficient travel distance DT to be calculated with high accuracy, and the object W can be pressed with high accuracy.

(5) According to the present invention, the control unit 2 detects the load value F (Z0) of the ram 31 on the object W using the detection unit 5, calculates the insufficient travel distance DT, and then controls the ram 31 to decelerate and move. This makes it possible to provide a press device 1 that can press the object W with high precision even when the travel speed of the ram 31 is high.

If the movement speed of the ram 31 is high, the time to calculate the missing movement distance DT is insufficient, and the calculation unit 20 may be delayed in sending a movement command for the missing movement distance DT to the command pulse generation unit 26, which may result in the movement of the ram 31 being stopped.

The load value F(Z0) varies depending on the movement speed of the ram 31. If the load value F(Z0) applied to the ram 31 is measured after the movement of the ram 31 is decelerated, the value of the load value F(Z0) fluctuates and the load value F(Z0) cannot be detected accurately. As a result, the insufficient travel distance DT cannot be calculated accurately, which is undesirable. When it is predicted that there will be insufficient time to calculate the insufficient travel distance DT and it is necessary to decelerate the movement speed of the ram 31, the calculation unit 20 calculates the insufficient travel distance DT before decelerating the movement of the ram 31.

In addition, after a movement command is sent from the calculation unit 20, a time delay occurs until the ram 31 completes the movement in response to the movement command. This time delay is unavoidable, particularly when the drive unit 4 is configured to include a servo motor 42. For example, the time it takes for the amount of rotation of the servo motor 42 to reach an amount of rotation equivalent to the "accumulated pulse" corresponds to this time delay. The distance between position ZT, which is the target position to which the set movement distance DS is moved, and position Z0 of the ram 31 at the time the movement command is sent, is the distance caused by the "accumulated pulse", and is the difference R shown in the above-mentioned (Equation 5).

When the difference R is large, the distance between the target position ZT and the position Z0 of the ram 31 at the time the movement command is sent becomes large, and the missing travel distance DT cannot be calculated accurately, which is undesirable. The difference R is directly proportional to the movement speed V of the ram 31 as shown in (Equation 6). Therefore, by slowing down the movement speed V of the ram 31, the difference R can be made smaller, and the calculation accuracy of the missing travel distance DT can be improved. Even when the movement speed of the ram 31 is slowed down in order to improve the calculation accuracy of the missing travel distance DT, the calculation unit 20 may calculate the missing travel distance DT before slowing down the movement of the ram 31.

As a result, the load value F(Z0) applied to the ram 31 is measured with high precision, and the insufficient travel distance DT is calculated based on the measured load value F(Z0), so that the insufficient travel distance DT is calculated with high precision. As a result, the object W can be pressed with high precision.

(6) According to the present invention, the control unit 2 transmits a movement command for the set movement distance DS to the drive unit 4 in several steps, and then transmits a movement command for the insufficient movement distance DT. There is a time delay before the rotation of the servo motor 42 reaches an amount of rotation equivalent to the "accumulated pulses" in the movement command for the set movement distance DS. The control unit 2 calculates the insufficient movement distance DT during this delay time.

This allows the control unit 2 to move the set travel distance DS and the insufficient travel distance DT without stopping the ram 31. As a result, the load value F (Z0) applied to the ram 31 can be detected with high accuracy without stopping the ram 31. This allows the insufficient travel distance DT to be calculated with high accuracy. As a result, the object can be pressed with high accuracy.

2. Other embodiments
Although the embodiments including the modified examples have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as well as in the scope and gist of the invention. The following is an example.

(1) In the above embodiment, the calculation of the insufficient travel distance DT is performed once at position Z0 during one press operation, but the calculation of the insufficient travel distance DT may be performed multiple times during one press operation. For example, the calculation unit 20 may calculate the insufficient travel distance DT1 for the first time at transmission position Z01 after transmitting a movement command for the set travel distance DS to the command pulse generating unit 26, calculate the insufficient travel distance DT2 for the second time at transmission position Z02 after transmitting the movement command for the insufficient travel distance DT1 to the command pulse generating unit 26, and transmit the movement command for the insufficient travel distance DT2 to the command pulse generating unit 26.

In this way, by calculating the insufficient travel distance DT multiple times during one press operation, even if the load value F (Z02) applied to the ram 31 changes due to the insufficient travel distance DT1, it is possible to accurately calculate the insufficient travel distance DT2. This makes it possible to provide a press device 1 that can press the object W with high accuracy.

(2) In the above embodiment, the desired press amount DP is the difference in distance between the position where the ram 31 contacts the object W when pressing begins and the post-processing position of the ram 31 after ideal pressing has been performed. However, the desired press amount DP is not limited to the movement distance of the ram 31. For example, the desired press amount DP may be a numerical value related to the volume of the press portion, etc. The set movement distance DS is the movement distance of the ram 31 corresponding to the desired press amount DP, assuming that no deflection occurs in the press device 1.

(3) In the above embodiment, the position ZT is set in advance, and the set movement distance DS is the distance that the ram 31 moves based on the position ZT that is pre-stored in the parameter storage unit 25. However, the set movement distance DS may also be set in advance and pre-stored in the parameter storage unit 25.

In addition, the items that are set in advance and stored in the parameter storage unit 25 are not limited to the position ZT or the set movement distance DS. For example, the desired press amount DP may be set in advance in addition to the position ZT and the set movement distance DS and stored in advance in the parameter storage unit 25. Alternatively, at least one of the position ZT, the set movement distance DS, and the desired press amount DP may be set in advance and stored in advance in the parameter storage unit 25.

(4) In the above embodiment, the set travel distance DS is the travel distance of the ram 31 corresponding to the desired press amount DP for pressing the object W, assuming that no bending occurs in the press device 1. However, the set travel distance DS is not limited to the above. The set travel distance DS may be selected by the operator as a distance such that the press amount when the object W is actually pressed is equal to or less than the desired press amount DP, and may be set in advance and stored in the parameter storage unit 25 in advance. The set travel distance DS may be selected by the operator as follows:

The set travel distance DS is preferably the same value as the travel distance of the ram 31 corresponding to the desired press amount DP, but may be a value selected so that when the ram 31 is moved by the set travel distance DS, the press amount of the object W that is actually pressed is equal to or less than the desired press amount DP. The desired press amount DP may be set separately from the position ZT or the set travel distance DS. The set travel distance DS may be a numerical value selected by the operator as follows:

In the case where the travel distance of the ram 31 corresponding to the desired pressing amount DP is 100 mm and the deflection amount δ is 2 mm, for example, 80 mm may be set in advance as the set travel distance DS and stored in advance in the parameter storage unit 25. In this case, the control unit 2 may add 20 mm, which is the difference between the set travel distance DS of 80 mm and the travel distance of the ram 31 corresponding to the desired pressing amount DP of 100 mm, and 2 mm for the deflection amount δ, to calculate the insufficient travel distance DT as 22 mm. By configuring in this way, even if the travel speed of the ram 31 is fast, the travel distance for measuring the load value F (Z0) applied to the ram 31 in advance can be specified by the set travel distance DS. As a result, it is possible to provide a press device 1 that can press the object W with high precision even if the travel speed of the ram 31 is fast.

In addition, when the travel distance of the ram 31 corresponding to the desired pressing amount DP is 100 mm and the deflection amount δ is 2 mm, it is possible to grasp in advance that the deflection amount δ for the total number of target pieces W is 1 mm or more, and for example, 101 mm may be set in advance as the set travel distance DS and stored in advance in the parameter storage unit 25. In this case, the control unit 2 may calculate the difference between the difference between the set travel distance DS of 101 mm and the travel distance of the ram 31 corresponding to the desired pressing amount DP of 100 mm, which is 1 mm, and the deflection amount δ of 2 mm, and calculate the insufficient travel distance DT as 1 mm. By configuring in this way, the travel distance for measuring the load value F (Z0) applied to the ram 31 in advance can be specified to a position close to the completion of pressing by the set travel distance DS. This allows the load value F (Z0) of the ram 31 to be detected more accurately. As a result, it is possible to provide a press device 1 that can press the target W with high accuracy.

As described above, the set movement distance DS may be selected by the operator as a distance such that the amount of pressing when the object W is actually pressed is equal to or less than the desired amount of pressing DP, and may be set in advance and stored in advance in the parameter storage unit 25.

1... Press device 2... Control unit 20... Calculation unit 21... Program memory unit 22... Display unit 23... Operation unit 231... Switch 232... Input circuit 24... Primary memory unit 25... Parameter memory unit 26... Command pulse generating unit 27... Servo motor driver 28... Encoder position counter 3... Pressurizing unit 31... Ram 31a... Female threaded portion 31b... Strain-generating column 32... Ball screw 4... Drive unit 41... Power transmission unit 41a, 41b... Pulley 41c... Belt 42... Servo motor 43... Encoder 5... Detection unit 51... Strain gauge 52... Communication unit 8... Base 9... Housing 9a... Enclosure 9b... Support 9c... Casing

Claims (6)

a ram for applying a load to an object to be pressed;
A drive unit that drives the ram;
a detection unit that detects a load value of the load of the ram against the object;
a control unit that controls the drive unit so that the ram applies a load to the object,
The drive unit includes a servo motor,
The control unit is
Based on a preset setting, a rotation amount of the servo motor is controlled to move the ram by a set moving distance such that a pressing amount when the object is actually pressed is equal to or less than a desired pressing amount;
calculating a shortage of movement distance of the ram that is insufficient for the desired press amount during a delay time due to accumulated pulses that are not allocated to the rotation amount of the servo motor while the ram is moving the set movement distance, based on the load value detected by the detection unit;
controlling the rotation amount of the servo motor so that the ram moves the insufficient movement distance;
Press equipment. the control unit performs control to move the ram the set movement distance and the insufficient movement distance without stopping the ram.
The press device according to claim 1 . The control unit calculates a deflection amount caused by a reaction force generated when the load is applied to the object by the ram, based on the load value detected by the detection unit, and calculates the insufficient movement distance based on the calculated deflection amount.
3. The press apparatus according to claim 1 or 2. the control unit calculates the insufficient movement distance based on a change amount of the load value detected by the detection unit with respect to a movement distance of the ram.
The press apparatus according to any one of claims 1 to 3. The control unit is
the load value of the ram with respect to the object is detected by the detection unit, the insufficient travel distance is calculated, and then control is performed to decelerate and move the ram.
The press apparatus according to any one of claims 1 to 4. the control unit transmits, to the drive unit, a movement command for the set movement distance in several steps, and then transmits a movement command for the insufficient movement distance.
The press apparatus according to any one of claims 1 to 5.

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