JP4197263B2 - Electrode device for projection welding - Google Patents

Description

[0001]
[Field of use belonging to the invention]
The present invention relates to a projection welding apparatus in which a projection (protrusion) is formed on a cylindrical workpiece , and a welding current is concentrated on the dotted or linear portion to flow and melt by heating and joining. For projection welding of cylindrical workpieces that have both the clamping function necessary for workpiece positioning and the power feeding function necessary for welding by simultaneously moving a plurality of electrode tips conforming to the outer diameter of the cylindrical workpiece in the centripetal direction of the workpiece The present invention relates to an electrode device.
[0002]
[Prior art]
As shown in FIG. 5, when projecting a counterpart metal plate W2 (including a pressed metal piece) to the open end surface of the cylindrical workpiece W1, a workpiece is pressed against the outer diameter or inner diameter of the hollow workpiece and opposed to each other. 2. Description of the Related Art Conventionally, a clamp electrode device having both a clamping function for positioning when determining a relative position between them and a power feeding function for forming a current path required for welding between workpieces is known.
[0003]
For example, as disclosed in Japanese Patent No. 2535284 and Japanese Patent No. 2613738, a conventional cylindrical workpiece clamping and feeding device includes a chuck rod having a tip made of a conductive wire member attached thereto, and the rod A chuck driving guide unit is known which has a chuck holder that concentrically overlaps with the chuck portion on the axis of the shaft and holds the workpiece of the chuck portion by a piston movement and opens and closes when opening.
[0004]
As shown in FIGS. 6 and 7, the outline of this type of apparatus is such that a plurality of slits 74 are formed on each of the chucks 70 of the movable side electrode and the fixed side electrode so that the spring force acts. A wedge surface 73 that engages with a tapered pressure surface 72 provided on the inner surface of the chuck holder 71 is provided on the outer periphery, and the thrust force of the actuator acting on the wedge surface is perpendicular to the axis of each chuck. It is made to act | operate and to be able to clamp | bond a to-be-welded object with the inner surface of a chuck | zipper. In this conventional example, the chuck 70 which also serves as an electrode presses and grasps the outer diameter of the cylindrical workpiece W1.
[0005]
In addition, the electrode device described in Japanese Patent Publication No. 63-9916 has a wedge surface that engages a tapered pressure surface provided on the inner surface of the chuck holder with a chuck that also serves as an electrode on the inner diameter of the cylindrical workpiece. The component of thrust of the actuator acting on the wedge surface is applied in the direction perpendicular to the axis of each chuck so that the workpiece can be tightened with the chuck.
[0006]
That is, in an apparatus for resistance-welding a plurality of second workpieces to the inner wall of a first workpiece of a cylindrical workpiece with a cylindrical inner diameter, the first electrode having a tapered portion and the tapered portion of the electrode are engaged. A plurality of auxiliary electrodes each having a tapered surface that can be used, and a second electrode disposed on the outer wall side of the first workpiece, and the first electrode is connected to the cylindrical first from the tapered portion side. By inserting along the substantially central axis of the work piece, pressure is applied to the plurality of second work pieces via the auxiliary electrode to perform resistance welding.
[0007]
[Problems to be solved by the invention]
Conventionally, when a metal plate is projection welded to the tip of a cylindrical workpiece, the collect chuck as described above is often used. This type of conventional collect chuck can maintain a high centripetal accuracy and at the same time allows a welding current to flow, but this type of electrode chuck device has a chuck stroke with a radius of about 0.5 mm to 1.0 mm. However, it may be impossible to implement depending on the work shape.
[0008]
In addition, the conventional collect chuck system converts the slide on the wedge surface that engages the tapered pressure surface into the clamping force of the chuck, so that the electrode wears quickly, and the chuck itself also changes whenever the diameter of the work piece changes. It must be changed, and the chuck is difficult to cope with changes in workpiece diameter. In other words, such a collect chuck system requires high taper machining accuracy, and the structure is complicated and it is difficult to support only cylindrical workpieces. If the shape of the workpiece is changed or changed, a new structural design is required.
[0009]
[Means for solving problems]
The present invention solves the above problems. The specific means is to form a protrusion on the cylindrical workpiece, superimpose a mating metal part on this protrusion, press the joint between the protrusions between the electrodes, flow a welding current, and heat and melt. In the projection welding apparatus, of the pair of electrode apparatuses facing each other, the electrode apparatus holding one of the cylindrical workpieces moves simultaneously in a centripetal or centrifugal direction opposite to the axial line of the cylindrical workpiece. A plurality of chuck jaws for simultaneously clamping or releasing the cylindrical workpiece with the electrode tips, a hinged crank lever for operating the chuck jaws, and a chuck actuator as a drive source for driving the crank lever. Each chuck body case, and each of the chuck body cases that are insulated and attached to the plurality of chuck jaws of the chuck body case. Pole base and the said electrode holder each electrode holder is attached to the electrode base outer diameter or the cylindrical workpiece plurality of electrode tip with respect to the wall surface of the inner diameter is mounted at a right angle and detachably, wherein the electrode base is flexible It is configured to be connected to the welding transformer via a reliable secondary copper plate, and it detects the applied pressure during welding between the cylindrical workpiece and the mating metal plate and monitors whether it is normal or abnormal Provided is an electrode device for projection welding characterized by comprising a sensor .
[0010]
Next, a guide pin fitted into the inner diameter of the cylindrical workpiece is provided, a step for positioning the workpiece is provided in the guide pin, the step is a small diameter portion inserted into the inner diameter of the cylindrical workpiece, There is provided an electrode device for projection welding which is composed of a large-diameter portion with which a lower end surface of an opening portion of an inserted workpiece abuts, and is set on the condition that a welding reference position of the workpiece is set by the step.
[0011]
Next, the welding pressure between the cylindrical workpiece and the mating metal plate is detected, and the detected value is compared with a preset pressure value to monitor whether the welding state is normal or abnormal. Provided is an electrode device for projection welding provided that a pressure sensor such as a load cell is attached to the electrode device.
[0012]
Next, the chuck jaw converts the linear motion of the slide portion by a single actuator built in the chuck body into the radial direction with respect to the axial line of the cylindrical workpiece via the crank lever. An electrode apparatus for projection welding is provided.
[0013]
Next, the electrode tip is divided into three directions at equal intervals of 120 degrees concentrically with respect to the axial line of the cylindrical workpiece, and the three-divided electrode tip is supplied with power that matches the outer diameter of the cylindrical workpiece. Provided is an electrode device for projection welding that has a surface and is detachably attached to each of the electrode holders.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a plan view showing an embodiment of an electrode apparatus for projection welding for carrying out the method of the present invention. FIG. 2 is also a side view. FIG. 3 shows the principle of the mechanism for driving the chuck jaws of the electrode device. FIG. 4 is a plan view showing a state in which the cylindrical workpiece is clamped by the electrode tip.
[0015]
FIG. 5 shows a cross section of the work piece. On the other hand, the workpiece includes a cylindrical workpiece or a rod-shaped workpiece having a circular cross section, a polygon, a cone, an ellipse, or a stepped shape. Here, a cylindrical work W1 made of low alloy steel is used as an optimum embodiment.
[0016]
The other workpiece is a mild steel part with a flange W2, but the part shape is not limited. As shown in the figure, the protrusion shape P is continuous like a ring projection formed on the opening end surface of the cylindrical workpiece (a protrusion shape cut by tilting the upper opening end of the cylindrical tube outward and inward). They may be linear or punctiform, such as irregularities, or wavy, such as saw teeth. The shape and dimensions of the protrusions vary depending on the welding conditions, as well as the workpiece shape, thickness, and material.
[0017]
In FIG. 1 and FIG. 2, although a general view of the projection welder is omitted, a pair of electrode devices facing the upper arm and lower arm of the main body are arranged. FIG. 1 shows an example of the lower electrode device 1 on the opposite side, which is constructed using the present invention. The upper electrode 2 on the upper side (see FIG. 2) is generally arranged in the direction perpendicular to the paper surface of FIG. 1 by an air cylinder or a servo motor (electrode tip) when the lower electrode device 1 is fixed. ) Move up and down.
[0018]
A series of processes from the work setting to the lower electrode device 1 to pressure welding and the completion of workpiece removal after welding are performed automatically by sequence program control or manually.
[0019]
In the lower electrode device 1 that holds the cylindrical workpiece W1, the chuck jaws 3 are arranged concentrically with the cylindrical workpiece in three directions at equal intervals every 120 degrees. A plurality of chuck jaws 3 from three directions move simultaneously inward (centripetal direction) of the cylindrical workpiece, and the drive source of the chuck jaw 3 is for one chuck disposed below the electrode device 1 Actuating by an actuator 4 such as a fluid pressure cylinder. The plurality of chuck jaws 3 are connected to a mechanism 5 that converts a linear motion by the cylinder piston into a right angle in the centripetal direction of the workpiece.
[0020]
The number of chuck jaws 3 is not limited to the three-way separation mode shown in the above embodiment, but can be separated and arranged at an arbitrary angle (direction) depending on the workpiece shape and dimensions.
[0021]
In this case, the conversion mechanism 5 is disposed inside the chuck body case 8 and, for example, a substantially L-shaped crank lever 7 that rotates about the hinge 6 is attached according to the number of chuck jaws 3. ing. An upper end 7a of the lever 7 is connected to a chuck jaw 3 supported in a horizontal direction so as to be slidable on the guide portion G, and a lower end 7b of the lever 7 is moved up and down along the guide rail 9 by the actuator 4. The slide parts 10 are connected to each other.
[0022]
In this way, the plurality of levers 7 are simultaneously rotated about the hinge 6 by moving the slide portion 10 up and down by the actuator 4, thereby bringing the plurality of chuck jaws 3 into the axis of the workpiece. On the other hand, it is possible to move at a right angle and simultaneously along the guide portion G from three directions in the radial direction.
[0023]
As shown in FIG. 3, an electrode base 11 is mounted on each chuck jaw 3 via an insulating plate 12 with a bolt B <b> 1. An electrode holder 13 is detachably attached to the electrode base 11 by a bolt B2.
[0024]
A plurality (divided into three) of split electrode tips 14 are respectively attached to the tips of the electrode holders 13. As shown in FIGS. 3 and 4, these electrode tips 14 are attached as bolts B3 so that they can be easily removed and replaced as consumables.
[0025]
Each electrode tip 14 has a curved clamp feeding surface 15 adapted to the radius of curvature with respect to the pressing surface of the cylindrical workpiece W1, and each of the electrode tips 14 has a clamping force from three directions (arrows). It is configured so that centripetal positioning of the workpiece can be easily performed by tightly contacting the wall of the workpiece outer diameter and automatically clamping the direction toward the centripetal.
[0026]
One polarity terminal of the power transformer (not shown) is connected to the upper electrode side, and the other polarity terminal is connected to each electrode base 11 side separated in three directions. In this case, the secondary conductor connected to the power transformer side and the electrode base 11 are connected via a flexible secondary copper plate 20 so as to correspond to the movement of each chuck jaw 3.
[0027]
An iron guide pin 16 is inserted into the center of the electrode device of the present invention, and the lower end of the guide pin 16 is attached to the lower arm 21 of the welding machine with a bolt B4. The guide pins 16 are fitted into the inner diameter of the cylindrical workpiece W1 in order to ensure the setting of the cylindrical workpiece W1 and to obtain positioning accuracy.
[0028]
The tip of the guide pin 16 is set slightly lower than the prescribed welding reference position of the cylindrical workpiece, and the small diameter portion 17 inserted into the inner diameter of the cylindrical workpiece and the lower end surface of the opening of the inserted workpiece are in contact with each other. The diameter portion 18 is integrally formed, and the step formed by the small diameter portion 17 and the large diameter portion 18 makes the welding reference position e of the cylindrical workpiece W1 simple when it contacts the lower end surface of the cylindrical workpiece w1 at a right angle. Can be set. Further, the guide pin 16 receives an excessive load when the upper electrode 2 is pressed, so that the protrusion is not crushed excessively, and deformation of the workpiece shape due to the excessive load can be prevented.
[0029]
In the apparatus of the present invention, a load cell 22 for detecting and detecting an overload including a deflection amount of the entire chuck main body case due to a pressing force at the time of welding between the cylindrical workpiece and a mating metal plate is provided on the axial center line of the cylindrical workpiece. It is incorporated between the lower arm 21 and the fixed plate 23. In this case, in the load cell 22, the lower arm 21 moves the linear guide unit 24 on the welding machine main body side together with the electrode device 1 by the pressure applied during projection welding. The welding quality is checked based on whether or not the displacement reaches a predetermined value.
[0030]
The chuck actuator 4 shown in FIG. 3 can be replaced by hydraulic / pneumatic pressurization using a fluid pressure cylinder or electric pressurization in which a ball screw and a screw nut are combined with an electric motor.
[0031]
The operation according to the present invention will be described below with reference to FIGS.
1 to 3 show a state in which the electrode tip 14 disposed on the lower electrode device 1 clamps the cylindrical workpiece W1 from three directions.
[0032]
First, to return to the state before the workpiece setting, the chuck actuator 4 of the electrode device 1 in the clamped state is reversely operated, and the slide portion 10 moves up the guide rail 9 so that the crank lever 7 uses the hinge 6 as a fulcrum. The chuck jaw 3 is rotated and moved to the left along the guide portion G, and the three electrode tips 14 are simultaneously separated from the guide pins 16 to return to the state of being released from the clamp.
[0033]
After the electrode tip 14 is opened, the cylindrical workpiece W1 is inserted from above the guide pin 16, and when the lower end surface of the opening of the cylindrical workpiece W1 hits the step of the guide pin, the welding reference position e of the cylindrical workpiece is set. Is set.
[0034]
After the cylindrical workpiece W1 is set, when air is supplied to the clamp side of the actuator 4 and the slide part 10 is lowered, the crank lever 7 is rotated around the hinge 6 and the chuck jaws 3 are moved all at once from the three directions. Is moved to the centripetal side of the workpiece W1. As a result, as shown in FIG. 4, the clamp feeding surface 15 of each electrode tip 14 is pressed against the outer diameter of the cylindrical workpiece W1 so as to surround a concentric circle from the direction of the arrow, thereby positioning the cylindrical workpiece.
[0035]
Next, the opposite flange W2 is set on the upper end surface of the opening of the cylindrical workpiece W1 held by the lower electrode device 1. In this case, the setting of the flange W2 is mechanically automatically performed by a robot or a parts feeder, or manually performed.
[0036]
When the flange W2 is set at a predetermined position, this is automatically detected immediately and the pressurizing actuator of the upper electrode device 1 is operated, and the upper electrode 2 is lowered to the flange side and a flange is attached to the upper end of the cylindrical workpiece W1. When a predetermined pressing force is applied, the load cell detects this pressing force, and it is stored in the capacitor up to the voltage value required for welding by a positive / negative charging circuit that sends an energization signal to the control device and stores the power from the power transformer. The welding current is supplied between the upper and lower electrodes between positive and negative by the control operation of the positive and negative charging circuit, the ring-shaped contact portion between the cylindrical workpiece W1 and the flange W2 is intensively heated and melted, and so-called projection welding is performed.
[0037]
Thus, when welding is completed, the upper electrode 2 and the chuck jaw 3 are reversely operated. When the welded cylindrical workpiece W1 is released from the electrode clamped state, the welded product and a new cylindrical workpiece are taken in and out, Prepare for the next welding process.
[0038]
In the present embodiment described above, the lower electrode device for projection welding of a cylindrical workpiece has been referred to. However, the idea of the present invention is that other embodiments than the case where the clamp electrode is pressed against the outer diameter of the cylindrical workpiece. As an example, for example, the guide pin is changed to an electrode, the electrode is divided in the vertical direction, the divided electrode piece formed by the division is inserted into the inside of the cylindrical workpiece, and the divided electrode is inserted in the direction of the workpiece axis by the chuck jaw. If it is made to move at the same time in the centrifugal direction, the clamp feeding surface of the electrode tip can be simultaneously pressed at right angles from the inside of the workpiece against the pressing surface of the cylindrical workpiece inner diameter.
[0039]
Moreover, although the electrode apparatus for projection welding was demonstrated in the present Example, it can be implemented also to the clamp electrode apparatus of other resistance welding machines, such as upset welding, spot welding, and seam welding, within the technical scope of the present invention. Needless to say.
[0040]
It should be noted that the object to be welded according to the present invention is not limited to a cylindrical workpiece, but also includes the rod-shaped or polygonal cross section described above, and other stepped cylindrical workpieces as shown in FIG. In this case, the shapes of the electrode tip and the power supply surface are variously changed in accordance with the shape of the counterpart workpiece.
【The invention's effect】
[0041]
As described above, according to the apparatus of the present invention, when another metal plate is projected and welded to the tip of the cylindrical workpiece, the chuck jaws are arranged in the axial direction of the cylindrical workpiece as compared with the conventional collect chuck. The electrodes are pressed at right angles and simultaneously against the wall surface of the outer diameter or inner diameter of the cylindrical workpiece to press-weld the joints, so that the centripetal positioning of the cylindrical workpiece is extremely It can be held easily and with high accuracy. In addition, the stroke of the electrode chuck is large and it can easily cope with changes in the workpiece shape.
[0042]
Further, according to the apparatus of the present invention, rather than converting the slide on the tapered wedge surface into the clamping pressure as compared with the conventional collect chuck method, the plurality of chuck jaws generate the thrust in the linear direction by a cylinder or the like. Constructed so that the clamp pressure works uniformly from multiple directions at the same time and perpendicular to the centripetal direction with respect to the axis of the workpiece. The electrode tip can be replaced at the same time, and the replacement of the electrode tip becomes much easier. The replacement of the entire conventional chuck is no longer necessary and the life of the electrode can be extended. This greatly reduces initial / running costs.
[0043]
Further, the positioning of the welding reference position of the cylindrical workpiece can be easily and accurately performed by the step of the guide pin provided in the electrode device of the present invention. In addition, the electrode structure can be designed in a small unit type.
[0044]
In addition, since the apparatus of the present invention can take a larger electrode stroke as compared with conventional split cone chucks, slide chucks, etc., it can cope with changes in workpiece diameter with flexibility, and a conventional new structure design becomes unnecessary. That is, when the diameter of the cylindrical workpiece is changed, the replacement part is small and can be easily replaced.
[Brief description of the drawings]
FIG. 1 is a plan view of a lower electrode device showing an embodiment of the method and apparatus of the present invention.
FIG. 2 is a side view of the same.
FIG. 3 is a schematic view showing an operation / configuration example of the apparatus of the present invention.
FIG. 4 is a plan view showing a state in which a cylindrical workpiece is simultaneously clamped from three directions (arrows) by the electrode tip of the apparatus of the present invention.
FIG. 5 is a view showing an appearance of a workpiece and a projection shape of a cylindrical workpiece.
FIG. 6 is a cross-sectional view schematically showing a conventional chuck type electrode device, and shows an electrode chuck that converts a slide on a wedge surface engaged with a tapered pressure surface into a grasping force.
FIG. 7 is a plan view schematically showing a conventional chuck type electrode device.
FIG. 8 is an explanatory diagram showing a stepped shape and a clamping direction (arrow) of the workpiece.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electrode apparatus 2 Upper electrode 3 Chuck jaw 4 Chuck actuator (fluid pressure cylinder) 5 Conversion mechanism 6 Hinge 7 Crank lever 8 Chuck body case 9 Guide rail 10 Slide part 11 Electrode base 12 Insulating plate 13 Electrode holder 14 Electrode chip 15 Power supply Surface 16 Guide pin 17 Small diameter portion 18 Large diameter portion 19 Secondary conductor 20 Secondary copper plate 21 Lower arm 22 Load cell 23 Fixing plate 24 Guide unit W1 Cylindrical workpiece W2 Flange

Claims (1)

In a projection welding apparatus in which a projection is formed on a cylindrical workpiece, a mating metal part is overlaid on the projection, and the joint on which the projection is superimposed is pressed between electrodes and a welding current is applied to heat and melt. Of the pair of electrode devices that face each other, the electrode device that holds one of the cylindrical workpieces moves simultaneously opposite to the centripetal or centrifugal direction with respect to the axial line of the cylindrical workpiece, and moves by the plurality of electrode tips. A chuck body case having a plurality of chuck jaws for simultaneously clamping or releasing the workpiece, a hinged crank lever for operating the chuck jaws, and a chuck actuator as a drive source for driving the crank lever; Each electrode base that is attached to the plurality of chuck jaws of the chuck main body case and is supplied with power, and the electrode Two in the electrode holder each electrode holder is attached to the over scan outer diameter or the cylindrical workpiece plurality of electrode tip with respect to the wall surface of the inner diameter is mounted at a right angle and detachably, wherein the electrode base is a flexible It is configured to be connected to a welding transformer through a secondary copper plate, and is composed of a pressure sensor for detecting whether the cylindrical workpiece and the mating metal plate are welded and monitoring whether it is normal or abnormal. An electrode device for projection welding characterized by the above.

Images