JP5313621B2 - Resistance welding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resistance welding machine capable of welding a workpiece with a predetermined height (thickness) and posture to a base material at all times. <P>SOLUTION: The resistance welding machine is provided with a height measuring part (53) for measuring the height of a workpiece (W) by bringing a upper electrode (30) in contact with the workpiece (W) placed on a base material (40); an air ejection passage (25) for jetting compressive air supplied from an air supply source from an axial center part of the upper electrode (30) toward the workpiece (W); a pressure sensor (29) for detecting pressure in the air ejection passage (25); and a determination part (84) for determining whether the energization to the electrode is necessary or not by inputting data of the height measuring part (53) and the pressure sensor (29). The electrode is energized, only when being determined to be "required" by the determination part (84). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a resistance welding machine for welding small parts such as nuts and bolts to a base material.

When welding a workpiece having a welding protrusion on the lower surface, for example, a nut, to the base material, it is necessary to place the nut on the base material in a vertical direction so that the protrusion abuts the base material. . In recent years, in order to save labor and increase productivity, a workpiece is supplied to a base material by a parts feeder. Although the parts feeder is designed so that the direction of the workpiece is normal, the vertical direction may be reversed for some reason and placed on the base material.
By the way, there existed patent document 1 as a conventional resistance welding machine. That is, a non-defective workpiece (nut) is placed on the base material, the upper electrode is lowered and brought into contact with the workpiece, the contact position is measured by the height measuring unit, and the measured value is applied to the workpiece reference value. Then, the production work is placed on the base material, the upper electrode is lowered and brought into contact with the production work, and the contact position is compared with the reference contact position. In some cases, the electrode is energized when it corresponds to the contact position, and when it deviates from the reference contact position, the electrode is not energized.

In the conventional apparatus, when workpieces having different heights are mixed, this can be detected to prevent sticking to the base material. However, for example, when a work (nut) having a welding projection on the lower surface is inverted upside down and placed on the base material, the measurement value by the height measurement unit is the same as that normally placed, The inverted workpiece is fixed to the base material as normal.
Japanese Patent Application Laid-Open No. 2007-90388.

  An object of the present invention is to obtain a novel resistance welder that prevents welding of a workpiece placed on a base material when the height of the workpiece is different, inverted placement or displacement.

In order to achieve the above object, the present invention is configured as follows. That is, the invention according to claim 1 includes a height measuring unit that measures the height of the workpiece by contacting the workpiece placed on the base material with the upper electrode, and compressed air supplied from an air supply source. An air ejection path that ejects from the axial center of the upper electrode toward the workpiece, and a pressure sensor that detects the pressure of the air ejection path are provided, and supply of compressed air to the air ejection path is started by When the electrode contacts the workpiece, the height measurement unit and the pressure sensor data are input and a determination unit is provided to determine whether the electrode is energized. Only when it is determined, the electrode is energized.
According to a second aspect of the present invention, the upper electrode is provided coaxially at the lower portion of the rod-shaped holder, and a concave portion is provided at the center of the lower surface of the upper electrode so that the air ejection path passes through the axial center portion of the upper electrode and the holder. At the same time, the lower end of the air ejection path is opened in the recess.

In the invention according to claim 1, when the prescribed workpiece is placed on the base material in a normal orientation, the measurement value of the height measurement unit when the upper electrode comes into contact with the workpiece becomes the reference value. In addition, the outlet of air ejected from the axial center of the upper electrode is closed by the workpiece, the pressure in the air ejection path rises, and the value of the pressure sensor becomes the specified pressure. As a result, the determination unit determines that energization of the electrodes is “necessary”, starts energization of the upper and lower electrodes, and the workpiece is welded to the base material.
On the other hand, when a workpiece with a height different from that of a regular product is placed on the base material, the measured value of the height measurement unit when the upper electrode contacts the work is different from the reference value, and the workpiece is placed on the base material. If the placed work is turned upside down or the placement position is shifted, a gap is generated between the upper electrode and the work, and the air blown from the axial center of the upper electrode is passed through the gap. It leaks to the outside and the value of the pressure sensor becomes lower than the specified value. In these cases, the determination unit determines that the energization of the electrode is “no”, the energization of the upper and lower electrodes is blocked, and the workpiece is not welded to the base material.
In addition, since the supply of compressed air to the air ejection path is set as a time when the upper electrode comes into contact with the work, the work is blown into the air ejection path at an unstable time when the work is not held under pressure by the upper electrode. The position will not be displaced by the air flow erupted from. For this reason, a workpiece | work can be welded to a base material with high precision.
The invention according to claim 2 can connect the air ejection path from the upper end portion of the holder to the air supply source, simplify the piping structure, and easily attach the holder to the frame of the resistance welder.

  Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is an enlarged side view of an essential part of FIG. 1, FIG. 3 is an enlarged sectional view of an upper electrode part, and FIG. 4 is a work placed upside down. FIG. 5 is an enlarged sectional view showing an operating state when different types of workpieces are placed, FIG. 6 is a perspective view showing types of workpieces applied to the embodiment, and FIG. Is a block diagram of a control device according to the present invention, and FIG. 8 is a flowchart of the control device.

  1 to 3, reference numeral 1 denotes a resistance welder (spot welder), and an upper arm 3 and a lower arm 4 are separated from each other vertically on a machine base 2 so as to protrude and be fixed in the front direction (rightward in FIG. 2). Then, a rod-shaped lower electrode holder 6 is clamped and fixed to the tip of the lower arm 4 via a lower clamp 5, and the lower electrode 7 is attached to the upper portion of the lower electrode holder 6. As shown in FIG. 3, a conical guide 8 is attached to the upper axial center of the lower electrode 7 so as to be able to project and retract, and the guide 8 is projected and biased upward by a spring.

  The cylinder 10 is attached downward to the tip of the upper arm 3, the rod 11 is protruded downward from the upper arm 3, and the upper clamp 13 is fixed to the lower end of the rod 11 via the support 12. A rod-shaped upper electrode holder 15 is fixed to the upper clamp 13 in the vertical direction, and an upper electrode 30 is fixed to a lower end portion of the upper electrode holder 15 so as to face the lower electrode 7.

As shown in FIG. 3, the upper electrode holder 15 has an upper through hole 16a formed through the shaft center, a pipe nut 17 is detachably screwed to the upper part, and an upper electrode 30 is detachably connected to the lower part. Is done. A cooling water inflow pipe 18 penetrating the central portion of the upper through hole 16 a is suspended and fixed to the axial center of the piping nut 17, and the upper end of the inflow pipe 18 is attached to the side of the piping nut 17. The cooling water inflow nipple 19 is communicated. A return water passage 21 having a diameter larger than that of the inflow pipe 18 and communicating with the upper through hole 16a of the holder 15 is formed in the lower shaft center portion of the pipe nut 17, and the return water passage 21 is formed on a side portion of the pipe nut 17. The attached cooling water outlet nipple 20 is communicated.

  A connecting nut 23 having an air flow passage 24 formed in the axial center thereof is detachably screwed onto the upper portion of the piping nut 17, and the central portion of the inflow pipe 18 is connected to the lower axial center portion of the connecting nut 23. The air ejection pipe 25 penetrating through the pipe is fixed in a suspended manner. An air supply pipe 26 is connected to the upper part of the connecting nut 23. The air supply pipe 26 connects a secondary supply pipe 26b to a primary supply pipe 26a connected to an air compressor via a pressure-reducing solenoid valve 27, and connects the secondary supply pipe 26b to the connecting nut 23. . The electromagnetic valve 27 is configured so that the pressure on the primary supply pipe 26a side is reduced to 0.12 to 0.13 Pa and is supplied to the secondary supply pipe 26b. The primary supply pipe 26a includes a pressure sensor 29. Is attached.

  As shown in FIG. 3, the upper electrode 30 has a socket 31 detachably taper-fitted to the lower part of the upper electrode holder 15, and a relay holder 32 detachably taper-fitted to the lower part of the socket 31, The electrode tip 33 is detachably screwed to the lower part of the relay holder 32. The lower part of the electrode tip 33 is cylindrical and has a recess 34 at the center of the lower surface. The concave portion 34 is adapted to fit the top of a conical guide 8 provided in the lower electrode 7.

A lower through hole 16b communicating with the upper through hole 16a of the pipe nut 17 is formed in the axial center portion of the socket 31, and the lower end of the lower through hole 16b is sealed in the upper axial center portion of the relay holder 32 so as to be sealed. The inverted space portion 35 is formed. In addition, a cylindrical detection cylinder 36 is fixed to the lower outer periphery of the relay holder 32 so as to protrude downward. The detection cylinder 36 surrounds the outer periphery of the electrode tip 33 with a predetermined gap, and its lower end protrudes slightly below the electrode tip 33.

  The aforementioned inflow pipe 18 passes through the upper and lower through holes 16a and 16b, and the lower end thereof faces the inversion space 35. Thereby, the cooling water flowing in from the inflow nipple 19 flows between the air ejection pipe 25 and the introduction pipe 18, and is inverted upward in the reversing space portion 35 to flow through the through holes 16 a and 16 b outside the inflow pipe 18. Then, it flows from the outflow nipple 20 toward the external cooling water tank to cool the upper electrode 30.

  The air ejection pipe 25 passes through the central part of the introduction pipe 18 and the central part of the electrode tip 33, and the lower end thereof is opened in the recess 34 of the electrode tip 33. Thereby, the compressed air supplied from the secondary supply pipe 26b is ejected into the recess 34. In FIG. 3, 71 is a workpiece receiver for receiving the base material 40, W is a work to be welded to the base material 40, and is a nut in this example.

As shown in FIGS. 6 (A) and 6 (B), the nut includes a nut W1 that protrudes downward from the lower surface of each corner of the main part of the welding projection L1, and a main part of the welding protrusion L2. There is a nut W2 projecting toward the outer side and downward from a lower portion of the corner portion, also root Ji kinds of holes of the nut W1, W2, there is M5, M6, M8, M10, M12 and the like, the height screws It depends on the type of hole.

  A main body control panel 45 of the resistance welding machine 1 is attached to the machine base 2, and an energization control device 50 is attached to the upper arm 3. The main body control panel 45 has a main control unit for driving the cylinder 10, energizing the upper and lower electrodes 30, 7, and the like, and predetermined operation buttons. A foot switch 46 (FIG. 2) disposed on the floor is connected to the main body control panel 45, and the resistance welding machine 1 is operated by stepping on the foot switch 46 and disposed between the electrodes 30 and 7. The welding work of the base material 40 and the workpiece (fixed object) W can be easily performed. The foot switch 46 is omitted when the resistance welding machine 1 is automatically operated.

  As shown in FIG. 2, the energization control device 50 includes a control board 52 and an encoder (height measurement unit) 53 that measures the height of a workpiece in a box-shaped case 51. The encoder 53 is connected to the control board 52 and its rotation shaft is horizontally arranged, and a pinion gear 54 fixed to the rotation shaft is engaged with a rack gear 55 extending in the vertical direction, and the lower portion of the rack gear 55 is moved downward from the case 51. And is bolted and fixed to the support 12 described above via the bracket 56. As a result, when the upper electrode 30 is moved up and down by the cylinder 10, the rack gear 55 is moved up and down in synchronization with this and the encoder 53 is rotated, and the rotation amount of the encoder 53 is output to the control board 52. It has become.

  A relay box 61 is connected to the energization control device 50, the drive circuit of the solenoid valve 27 and the signal circuit of the pressure sensor 29 are connected to the relay box 61, and an input device (a personal computer) having a keyboard in the relay box 61 ) 62 is connected. The input device 62 operates the keyboard to set the type of workpiece W to be fixed to the base material 40, the fixing order, the operation of the electromagnetic valve 27, the pressure value of the pressure sensor 29, etc. It is stored in the energization control device 50 (control board 52) or the operation of the robot 65 described later is set.

  The movement of the base material 40 to the workpiece fixing position is performed by a robot 65. As shown in FIG. 1, the robot 65 connects two first and second arms 68 and 69 that rotate up and down around a horizontal axis to a support column 67 that is erected and fixed to a base 66. From the robot control unit 72 attached to the support base 66 side, a third arm 70 that rotates about the vertical axis is connected to the distal end of the workpiece, and a work receiver 71 that receives the base material 40 is attached to the third arm 70. In response to this command, the first to third arms 68 to 70 are driven and controlled, and the base material 40 supported by the workpiece receiver 71 is sequentially moved to the fixing position (electrode position) of each workpiece W. A predetermined workpiece W is supplied to the fixed position of the workpiece W by a shooter 73 of a parts feeder so as to face the upper electrode 30 on the base material 40.

  FIG. 7 shows a block diagram of the energization control device 50. In FIG. 7, reference numeral 80 denotes a setting unit for setting the initial position and measurement accuracy of the encoder 53, operating the input device (personal computer) 62, and the order and height of the workpieces W to be fixed to the base material 40. The opening / closing timing of the valve 27, the operation value by the pressure sensor 29, and the like are set, and the set data is stored in the storage unit 81.

  When the upper electrode 30 and the rack gear 55 are moved downward by the cylinder 10 and the upper electrode 30 comes into contact with the workpiece W placed on the base material 40 and the load on the cylinder 10 reaches a predetermined value. In addition, the height of the workpiece W is measured from the amount of rotation of the encoder 53 by the rack gear 55. The pressure detector 83 detects the pressure in the air ejection pipe 25 by the pressure sensor 29. 84 denotes a determination unit that compares the data of the height measurement unit 82 and the pressure detection unit 83 with the data of the storage unit 81, and determines that energization is “necessary” when normal, and the upper and lower electrodes are energized by the energization unit 85. 30 and 7 are energized. In the case of an abnormality, energization is determined as “no”, the energization prohibition unit 86 prohibits the energization of the upper and lower electrodes 30 and 7, and the notification unit 87 displays an abnormality display or alarm. Operate.

  FIG. 8 is a flowchart showing the operation of the energization control device 50. In FIG. 8, S1-S15 show each step. When the start switch is pressed (S1), the robot 65 operates to position the workpiece fixing portion of the base material 40 on the lower electrode 7, and a predetermined workpiece W1 from the shooter 73 to the workpiece fixing portion of the base material 40. Supply (S2).

   Next, the main body switch is turned on (S3), the cylinder 10 is extended, the upper electrode 30 is lowered (S4), and the rack gear 55 is lowered via the bracket 56, and the encoder is connected via the pinion gear 54. 18 is rotated (S5). When the upper electrode 30 comes into contact with the workpiece W1 (S6), the electromagnetic valve 27 is opened (S7), compressed air is supplied from the secondary supply pipe 26b to the air ejection pipe 25, and the axial center portion of the upper electrode 30 is reached. To the workpiece W (W1).

  When the upper electrode 30 comes into contact with the workpiece W, the height (thickness) of the workpiece W is measured from the rotation amount of the encoder 18 by the height measuring unit 82, and the height of the workpiece W is normal by the determination unit 84. Is determined (S8). Further, the pressure detection unit 83 inputs a signal from the pressure sensor 29, and the determination unit 84 determines whether or not the air pressure in the air ejection pipe 25 is normal (S9).

  In this case, as shown in FIG. 3, when the work W is placed on the base material 40 in a normal orientation, the electrode tip 33 of the upper electrode 30 contacts the work W. When contacted, the measured value of the height measuring unit 82 becomes the reference value (normal), and the outlet of the air ejected from the axial center of the electrode tip 33 is the guide W of the workpiece W and the lower electrode 7. And the pressure in the air ejection pipe 25 rises, and the value of the pressure sensor 29 becomes a prescribed pressure (normal). As a result, the determination unit 84 determines that energization of the electrode is “necessary”.

  However, when the workpiece W having a height different from that of the regular product is placed on the base material 40, the measurement value of the height measurement unit 82 is different from the reference value, and the determination unit 84 determines whether or not the electrode is energized. Determined. As shown in FIG. 4, when the regular workpiece W is turned upside down and placed on the base material 40, the protrusion L <b> 1 of the workpiece W comes into contact with the electrode tip 33 and the electrode tip 33 and the workpiece W are placed. A gap (a) occurs between the two. Further, as shown in FIG. 5, when a workpiece W3 having a diameter larger than that of a regular product is placed on the base material 40, or when the placement position of the regular workpiece W is shifted to the side, the detection body is detected. 36 collides with the outer periphery of the workpieces W3 and W1, the measured value of the height measuring unit 82 is different from the specified value, and a gap (A) is generated between the workpieces W3 and W1 and the guide 8 of the lower electrode 7. Then, the air ejected from the axial center portion of the electrode tip 33 of the upper electrode 30 leaks to the outside through the gaps (a, b), and the value of the pressure sensor 29 becomes lower than the specified value. It is determined that the energization is “no”.

  If it is determined normal in S8 and S9, the process proceeds to S10, a predetermined current is passed through the upper and lower electrodes 30 and 7 in the energization unit 85 (S10), the workpiece W is welded to the base material 40, and If it is determined that there is an abnormality in S8, S9, the process proceeds to S14, the energization prohibiting portion 86 prohibits the energization of the upper and lower electrodes 30, 7, and the notifying portion 87 activates an abnormality display or alarm ( S15).

  When the welding of the workpiece W is completed in S10, the upper electrode 30 is raised (S11), and the process proceeds to S12 to determine whether or not the work is completed. If the work is not completed, the process proceeds to S2, and if the work is completed, the process proceeds to S13. Proceed and exit the control program.

It is a perspective view which shows the Example of this invention. It is a principal part enlarged side view of FIG. It is an expanded sectional view of an upper electrode part. It is an expanded sectional view showing an operation state when a work is placed upside down. It is an expanded sectional view which shows the operation state when a different kind of workpiece | work is mounted. It is a perspective view which shows the kind of workpiece | work applied to an Example. It is a block diagram of the control apparatus by this invention. It is a flowchart of a control apparatus.

Explanation of symbols

1 Resistance welder (spot welder)
2 machine 3 upper arm 4 lower arm 5 lower clamp 6 lower electrode holder 7 lower electrode 8 guide 10 cylinder 11 rod 12 support 13 upper clamp 15 upper electrode holder 16a upper through hole 16b lower through hole 17 piping nut 18 inflow pipe 19 Inflow nipple 20 Outflow nipple 21 Return water passage 23 Connection nut 24 Flow passage 25 Air ejection pipe 26 Air supply pipe 26a Primary supply pipe 26b Secondary supply pipe 27 Electromagnetic valve 29 Pressure sensor 30 Upper electrode 31 Socket 32 Relay holder 33 Electrode tip 34 Recess 35 Inversion space part 36 Detection body 40 Base material 45 Main body control panel 46 Foot switch 50 Current supply control device 51 Case 52 Control board 53 Encoder (height measurement part)
54 pinion gear 55 rack gear 56 bracket 57 power switch 58 power lamp 59 setting button 60 adjustment knob 61 relay box 62 input device 65 robot 66 base 67 support 68 first arm 69 second arm 70 third arm 71 work support 72 robot controller 73 Shooter 80 Setting unit 81 Storage unit 82 Height measurement unit 83 Pressure detection unit 84 Judgment unit 85 Energization unit 86 Energization prohibition unit 87 Notification unit W (W1, W2) Workpiece (nut)
L1, L2 protrusion

Claims (2)

A height measuring unit (53) that measures the height of the workpiece (W) by bringing the upper electrode (30) into contact with the workpiece (W) placed on the base material (40), and supplied from an air supply source An air ejection path (25) for ejecting the compressed air from the axial center of the upper electrode (30) toward the workpiece (W), and a pressure sensor (29) for detecting the pressure of the air ejection path (25) ), And the supply of compressed air to the air ejection path (25) starts when the upper electrode (30) comes into contact with the workpiece (W), and the height measuring unit (53) and the pressure sensor A determination unit (84) is provided to input the data of (29) and determine “necessity / non-necessity” of energization to the electrode, and energize the electrode only when the determination unit (84) determines “necessity” A resistance welding machine characterized by:   The upper electrode (30) is provided coaxially at the lower part of the rod-shaped holder (15), and a recess (34) is provided at the center of the lower surface of the upper electrode (30), so that the upper electrode (30) and the holder (15) The resistance welding machine according to claim 1, wherein the air jet passage (25) is passed through the axial center portion, and the lower end of the air jet passage (25) is opened in the recess (34).

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