JPS6236824B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling a main shaft transmission of an NC lathe.

Conventionally, NC lathes have generally used variable speed motors (DC or AC) as the spindle drive motors, but this has the disadvantage that the output decreases in the low speed range.

To solve this problem, a method has been adopted in which a transmission is inserted between the motor and the main shaft.

However, when using a transmission with multiple gears, selecting the optimal gear is a tedious task, and with NC lathes this task is left to the operator.

However, if the transmission has about two stages, the problem is small, but when a multi-stage transmission is used, the problem becomes very serious.

Therefore, the present invention automatically selects the optimum gear stage based on the processing information of the workpiece.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the structure of the present invention shown in the drawings will be described below.

First, an NC lathe is equipped with a computer consisting of an input device, a storage device, a calculation device, a control device, and an output device. Machining information, tool information, etc. are input through the input device, and the workpiece checked on the spindle is automatically processed. It is something to be processed.

The above processing information includes the shape of the workpiece (external diameter cutting,
Internal diameter machining, thread cutting, grooving, rough machining, rough finishing machining, finishing machining, etc.), dimensions (dimensions in the spindle direction and radial direction), cutting conditions (cutting speed, depth of cut,
(whether the peripheral speed is constant or not) are input for each machining process.

As shown in Figure 1, the target NC lathe transmission has stages 1 to m, and each main shaft rotation speed range is M/g ₁ to M/g ₁ . K 2nd stage is M/g ₂ ~ M/g ₂・K 3rd stage is M/g ₃ ~ M/g ₃・K: 1st stage is M/g ₁ ~ M/g ₁・K: mth stage It is assumed that the stages are defined as M/ _gn to M/ _gn ·K.

However, M: Maximum motor rotation speed (rpm) g ₁ : 1st stage gear ratio
(Motor rotation speed/spindle rotation speed) g ₂ : 2nd stage 〃 〃 g ₃ : 3rd stage 〃 〃 : g _i : i-th stage 〃 〃 : g _n : m-th stage 〃 〃 (however, g ₁ ＞g ₂ ＞g ₃ ＞…＞g _i ＞…＞g _n ) K: Ratio between the maximum and minimum rotation speed of the motor in the constant output range (minimum motor rotation speed =
M/K).

Then, the NC calculation unit calculates the required rotational speed of the spindle necessary for machining from the input machining shape of the workpiece, radial dimension of the machining position, and cutting speed.

The procedure will be explained below using the flowchart shown in FIG.

First, in the process number initial setting step 1, the process number N is set to N=0, then in the process number setting step 2, the process number N is set to N=N+1, and then in the confirmation step 3, data is set for the process. If the answer is "NO", the end signal (RET) is sent, but normally it is "yes", so if "constant circumferential speed" is specified for the N process in confirmation step 4, the end signal (RET) will be sent. Confirm whether or not. In other words, when the machined shape is a tapered shape or an arc shape, if the spindle rotation speed is constant, the circumferential speed will change in proportion to the size of the radius, and in order to prevent the machining accuracy from changing in each part, it is usually For these shapes, the peripheral speed is specified to be constant.

If the answer is "yes" in the above confirmation step 4, the maximum value (r _nax ) and minimum value (r _nio ) are selected from the radial dimensions of the N process in the selection step 5, and are temporarily stored in memory before the next confirmation step. Step 6 allows you to confirm whether the process in question is thread processing. If “yes” in the confirmation step 6 above, r _nax is determined in the calculation step 7.
and r _nio , r _nax , r _nio = r _nax + r _nio
/2 is stored and the process moves to the next calculation step 8.
Incidentally, if "NO" in the above-mentioned confirmation step 6, the process immediately proceeds to calculation step 8.

In the above calculation step 8, the minimum rotation speed n _L (rpm) and maximum rotation speed n _H (rpm) of the N process are calculated and stored as n _L = 500V/π・r _nax n _H = 500V/π・r _nio , respectively. .

However, V: input peripheral speed (cutting speed) m/
min π: Pi Percentage Then, in confirmation step 9, it is confirmed whether the previous process, ie, the "N-1" process, is in the same group.

The above-mentioned same group means the same processing mode, and is divided into groups such as "outer diameter cutting", "inner diameter cutting", "front cutting", "groove cutting", and "thread cutting".

In addition, if "NO" is determined in step 4 for checking constant circumferential speed, that is, if constant circumferential speed is not specified for the N process, the rotational speed input as both n _L and n _H is determined in setting step 10. n (rpm) is set, and the process moves to confirmation step 9.

If “NO” in confirmation step 9, set the minimum rotation speed n _L in the same group in setting step 11.
(M) and maximum rotation speed n _H (M) respectively n _L (M) =
Set as n _L , n _H (M) = n _H.

However, if the answer is "yes" in confirmation step 9,
In confirmation step 12, the minimum rotation speed n _L (M) of the N process and the previous time in the same group is compared with the minimum rotation speed n _L of the N process, and n _L
If (M)>n _L is "yes", that is, the current n _L is smaller, then in the next setting step 13, n _L (M) = n _L
If "NO", go to setting step 13.
is skipped and the process immediately proceeds to the next confirmation step 14.

In confirmation step 14, the maximum rotation speed n _H (M) up to the previous time in the same group as the N process is compared with the maximum rotation speed n _H of the N process,
If n _H (M)<n _H is "yes", that is, the current n _H is larger, then in the next setting step 15, n _H (M) =
_nH , and if "NO", skip setting step 15 and immediately proceed to the next pseudo process number setting step 16, and set N'=N. and,
In the next confirmation step 17, the next process, that is, (N′+
1) Check whether the processes are in the same group,
If "yes", the process returns to the first step number setting step 2 and the same process is repeated.

That is, from step 2 to step 17, the maximum rotation speed n _H (M) and minimum rotation speed n _L (M) (in other words, the required rotation speed range of the spindle) within the same group are calculated. be. Therefore, in the process of calculating the maximum rotational speed _nH and minimum rotational speed _nL for each machining process, if the same group of processes is continuous, the above process is repeated.
As a result, the maximum rotation speed n _H for each group
(M) and the minimum rotation speed n _L (M) will be calculated.

When one group is completed, a determination of "NO" is issued in the confirmation step 17, and the process moves to the next mission selection step 18, where the requested rotational speed range n _H (M) to n _L of that group is determined.
The optimum gear position for (M) is selected.

When the transmission speed of the group is selected in the mission selection step 18, the selected transmission speed is written in the N' step (i.e. N′-1) process (i.e. 1 of N process
It is confirmed whether or not the previous process) is in the same group.
If “yes”, in step number setting step 21
N'=N'-1 is set, and the same number of mission stages is written in the previous step in step 19, and this is repeated for all the same group. That is, when processes in the same group are consecutive, the number of stages of the processes in the group is all set to be the same. The reason for this is that machining within the same group is often performed continuously, and in the case of a transmission that takes time to change gears when moving from one process to the next,
This is because the speed change operation may be delayed and machining accuracy may deteriorate.

When the writing of the mission stage numbers for all processes in the same group is completed, a "NO" determination will be made in the confirmation step 20, and the first process number will be set again in order to perform the same process again for the next group. Return to step 2,
After that, the above operation is repeated until all the processes are completed. When all the processes are completed and the processing returns to the next process and comes to confirmation step 3, there is no data for the next process, so the end signal is emitted. (RET) appears and ends.

In addition, in the above explanation, the required rotation speed range of the main shaft is calculated for each group, but in the case of a transmission in which gear shifting operation is performed at high speed, the required rotation speed range for each process is calculated. , the number of transmission stages can be selected each time.

Next, the procedure for selecting the number of mission stages in the mission selection step 18 will be explained with reference to the flowchart of FIG.

Therefore, first, the maximum rotation speed n _H (M) obtained earlier in the first stage high speed comparison step 22 and the maximum spindle rotation speed M/g ₁ in the first stage are calculated as follows: n _H (M)≦M/g ₁ A comparison is made, and if "yes", the first gear is selected in a first gear instruction step 23.

If "NO" in the comparison step 22, the second stage low speed comparison step 24 compares the previously obtained minimum rotation speed n _L (M) and the second stage main shaft minimum rotation speed M/g ₂ .
A comparison is made with n _L (M) < M/g ₂ K, and if "yes", the first gear is selected, and if "no", the second gear high-speed comparison step is selected. 25.

In the second stage high speed comparison step 25, the maximum rotation speed n _H (M) and the second stage main shaft maximum rotation speed M/g ₂ are compared so that n _H (M)≦M/g ₂ is satisfied. ”, it is checked in confirmation step 26 whether the machining of the group (or process) is finishing machining, and if “yes”, the second
In step 27, the second gear is selected. However, when the answer is "NO" in the confirmation step 26, a comparison of {n _H (M) - M/g ₁ }×C≦M/g ₁ - n _L (M) is further performed in a comparison step 28, and If the answer is "yes," the first gear is selected, and if the answer is "no," the second gear is selected. In the above formula, C is a high speed/low speed selection coefficient; when C is increased, priority is given to high speed gears, and when C is decreased, priority is given to low speed gears.

This means that if the machining of the group (or process) is not finishing but rough machining or rough finishing, the ratio at which the required spindle rotation speed range overlaps with the rotation speed range of the first stage is greater than the predetermined value. In rough machining and rough finishing machining, even if the required rotation speed range is not satisfied in the high speed range, depending on the degree, it is better to rotate at a low speed to increase the spindle torque. This is because it becomes large, which is preferable.

When the second stage high speed comparison step 25 is NO, the third stage low speed comparison step 29 compares the minimum rotation speed n _L (M) and the minimum spindle rotation speed M/g ₃ ·K in the third stage. Compare n _L (M) < M/g ₃・K, and if "yes", proceed to step 2.
Go back to step 6 and make the same decision, if “NO”,
The process moves to the third high-speed comparison step 30. From then on, the configuration is the same up to the m-th stage, so the explanation will be omitted, but "yes" at the determination step of n _H (M) ≦ M/g _i means, in other words, the rotation speed range includes the required rotation speed range. This means that the lowest speed is the i-th speed among the speeds with n _L (M) <
In other words, "yes" in the determination step of M/g _i +1・K means that the rotation encompasses the lowest value of the required rotation speed when there is no gear stage that has a rotation speed range that includes the entire required rotation speed range. This means that the highest speed among the several speed ranges is the i-th speed.

In short, in this embodiment, the mission selection criteria is 1: Do not rotate faster than the input circumferential speed/rotation.

2. Use a constant output range as much as possible (give priority to low speed gears).

3 If either is acceptable, rough cutting/rough finishing...output (torque) priority (low speed gear priority) Finishing...high speed priority (high speed gear priority) 4.Mission shifting is not performed within the same group. (For transmissions that take time to shift) The following four items are taken into consideration.

In response to a gear change command based on the gear position set in this manner, an appropriate actuator such as a hydraulic pressure, a motor, or an electromagnet is operated to automatically change the gear position of the transmission.

As explained above, this invention is achieved by inserting a transmission capable of changing speeds in multiple stages between the motor and the main shaft.
In an NC lathe, the required rotation speed range of the main spindle required for machining the workpiece is calculated based on the input machining information, and this required rotation speed range and the spindle rotation speed at each gear of the transmission are calculated. If there is a gear that has a rotation speed range that includes the required rotation speed range, then the rotation speed range of the gear that is one step lower than the lowest speed among the corresponding gears. and the required rotational speed range, and if the required rotational speed range overlaps by a predetermined ratio or more, the gear on the low speed side of the first gear is set as the gear for the machining, and the overlap is predicted. If the ratio is below the predetermined ratio, the lowest gear among the applicable gears is set as the gear for the processing, and if there is no gear that has a rotation speed range that includes the required rotation speed range, then , 1 from the highest gear among the gears having the lowest speed value in the required rotation speed range in that rotation speed range.
Compare the rotational speed range of the gear on the lower speed side with the required rotational speed range, and if the overlap is less than a predetermined ratio of the required rotational speed range, use the highest speed as the gear for the processing. If the overlap is greater than or equal to a predetermined ratio, the gear on the low speed side of the first stage is set as the gear for the processing.
Unlike variable speed motors, there is no problem of output loss in the low speed range, and the optimum gear stage can be automatically selected based on the machining shape, dimensions and cutting conditions of the workpiece, reducing the burden on the operator. This method can reduce input errors and prevent input errors, and can exhibit excellent performance as a main spindle transmission control method for this type of NC lathe.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between each gear ratio and the spindle rotation speed of the present invention, Fig. 2 is a flow chart showing a specific example of the control method of the present invention, and Fig. 3 is a diagram showing the relationship between each gear ratio and the spindle rotation speed of the present invention. It is a flowchart diagram showing the main points.

Claims (1)

[Claims] 1. In an NC lathe in which a transmission capable of changing speeds in multiple stages is inserted between a motor and a main spindle, a required rotation speed range of the main spindle required for machining a workpiece is input. Calculations are made based on the processing information, and the required rotation speed range is compared with the main shaft rotation speed range of each gear of the transmission, and it is determined that there is a gear position that has a rotation speed range that includes the required rotation speed range. If so, compare the rotation speed range of the gear position one step lower than the lowest speed among the applicable gear positions and the above-mentioned required rotation speed range, and check that the required rotation speed range overlaps by a predetermined ratio or more. If so, the gear on the one-speed lower speed side is set as the gear for the machining, and if the overlap is less than a predetermined ratio, the lowest gear among the applicable gears is set as the gear for the machining. and if there is no gear that has a rotation speed range that includes the required rotation speed range, then the highest speed among the gears that has the lowest speed value in the required rotation speed range in that rotation speed range. Compare the rotational speed range of the gear position one step lower than the above-mentioned required rotational speed range, and if the overlap is less than a predetermined ratio of the required rotational speed range, the highest speed gear is changed to the gear for the relevant machining. A method for controlling a spindle transmission of an NC lathe, characterized in that the speed is set as a gear, and if the overlap is greater than a predetermined ratio, the gear on the one-speed lower speed side is set as the gear for the machining. 2. In the method for controlling the spindle transmission of an NC lathe described in paragraph 1, if the machining is finishing, one of the gears that has a rotation speed range that includes the required rotation speed range, regardless of the overlap ratio. Set the lowest gear, or if there is no corresponding gear, set the lowest speed value in the required rotational speed range to the highest gear among the gears in that rotational speed range as the gear for the relevant machining. A method for controlling the spindle transmission of an NC lathe, which is characterized by: 3 In the spindle transmission control method for an NC lathe described in paragraph 1 or 2, when calculating the required rotation speed range of the spindle based on the input machining information of the workpiece, the machining mode of each machining process is determined. An NC lathe characterized in that when the same group continues, the required rotation speed range for the group is calculated, and the gear stage for the group is thereby set by the method of item 1 or item 2. Main shaft transmission control method. 4 In the spindle transmission control method for an NC lathe described in paragraph 1 or 2, when calculating the required rotation speed range of the spindle based on the input machining information of the workpiece, the spindle 1. A method for controlling a spindle transmission for an NC lathe, comprising calculating a required rotational speed range for each process and individually setting a gear stage for each process by the method set forth in item 1 or item 2. 5 In the spindle control method for an NC lathe described in paragraph 1, if the maximum speed value in the required rotation speed range is smaller than the maximum speed value in the rotation speed range of the lowest gear among all gears of the transmission, or the required rotation If the lowest speed value in the number range is smaller than the lowest speed value in the rotational speed range of a gear position one step higher than the previous lowest gear, the lowest speed is set as the gear for the processing. N.C.
How to control the spindle transmission of a lathe.