JP7539618B2 - Electric Resistance Welding Electrodes - Google Patents

Description

The present invention relates to an electric resistance welding electrode that detects whether a component is set on a counter electrode.

Japanese Patent Application Laid-Open No. 10-58158 describes an electrode that detects whether a part such as a projection bolt is set correctly on a mating electrode.

Japanese Patent Application Publication No. 10-58158

The above-mentioned patent document describes that when a component is correctly held by the counter electrode, the welding current is normally passed through and welding is completed, and that if a component is not held by the counter electrode, the absence of the component is detected.

The electric resistance welding electrode described in Patent Document 1 has a detection part that moves back and forth within the electrode body, which is a complex combination of multiple parts, such as a synthetic resin sliding member, a metal detection pin, a washer, and a bolt. This makes the seating of the coil spring unstable, which can lead to poor electrical conductivity in this area, poor conductivity between multiple parts, and an increase in the labor required for assembling the multiple parts, resulting in a lack of improvement in productivity.

The present invention has been provided to solve the above problems, and aims to improve the electrical conductivity to the detection member that moves back and forth, simplify the structure, and achieve improved productivity and operational durability, etc.

The invention described in claim 1 is
an electrode body having a circular cross section and made of a conductive metal material, the electrode body being composed of a first member connected to a forward/backward driving means such as an air cylinder, a second member connected to the first member via a threaded portion, and a third member connected to the second member via a threaded portion and having a flat pressing end surface;
A large diameter hole is formed in the first member and the second member,
A small diameter hole is formed in the third member,
a main guide tube which is a tubular member made of insulating synthetic resin material and has a circular cross section is fitted into the large diameter hole of the second member and the main guide tube is fixed to the electrode body, and an auxiliary guide tube which is a tubular member made of insulating synthetic resin material and has a circular cross section is fitted into a small diameter hole formed in the third member and has a diameter smaller than the large diameter hole, and the auxiliary guide tube is fixed to the electrode body, so that the inner surface of the large diameter hole of the second member and the inner surface of the small diameter hole of the third member are covered by the main guide tube and the auxiliary guide tube,
A main detection member made of a conductive metal material and having a circular cross section is slidably fitted in the main guide tube,
a secondary detection member having a circular cross section and a smaller diameter than the primary detection member and made of a conductive metal material and integrated with the primary detection member, the secondary detection member being fitted in the secondary guide tube in a slidable state;
In a standby state before the advancing operation, the length of the secondary detection member is set so as to protrude beyond the pressing end face of the electrode body,
A flat conductive end surface that improves electrical conductivity to the main detection member is formed at the end of the main detection member by an end surface of the main detection member itself;
a compression coil spring is inserted between an electrically conductive terminal plate disposed in an insulated state at an inner end of the large diameter hole in the first member and an electrically conductive end face of the main detection member;
The device is configured such that three members, namely, a first member in which an electric terminal plate is disposed, a second member in which a main guide tube is fitted and in which a main detection member and a compression coil spring are inserted, and a third member in which a sub-guide tube through which a sub-detection member passes is fitted , are integrated via a screw portion;
The main guide tube has an open shape on the first member side and a bottom plate on the third member side with a through hole through which the secondary detection member passes.
The thickness of the main guide cylinder and the thickness of the bottom plate of the main guide cylinder are set to be approximately the same thickness dimension,
When the third member is integrated with the second member via the screw portion, an end of the auxiliary guide tube is configured to come into contact with the bottom plate;
This is an electric resistance welding electrode characterized in that a conducting wire for a detection current is connected to the current-carrying terminal plate and the electrode body.

When a component is properly held on the opposing electrode, a conductive circuit is formed which consists of the conductive wire, terminal plate, compression coil spring, conductive end face, detection member consisting of a main detection member and a secondary detection member, part of the component, the electrode body, and the conductive wire. This conductivity confirms that the component is properly held on the opposing electrode, and this confirmation signal triggers the passage of welding current to complete the welding.

Since the detection member has a simplified structure formed by the main detection member and the sub detection member, it can be easily manufactured by cutting a long and thin metal material or by joining the sub detection member to the main detection member. By adopting the above-mentioned manufacturing method, the conductivity from the main detection member to the sub detection member is ensured.

The main and auxiliary detection members made of conductive metal material can be cylindrical in shape, and the auxiliary detection member can be a round bar with a smaller diameter than the main detection member. Therefore, the metal detection member can be simplified in shape, consisting of a large-diameter member and a small-diameter member. In addition, since the detection members of such simplified shape are housed in the main guide tube and the auxiliary guide tube made of insulating synthetic resin material, the electrode body contains a cylindrical member made of synthetic resin and a cylindrical or round bar-shaped member made of metal, simplifying the structure of the electrode as a whole.

The current-carrying end surface formed on the end of the main detecting member is flat, so that the compression coil spring is seated in a good contact state, and the current from the compression coil spring to the main detecting member is good. The main detecting member and the sub detecting member slide within the main guide tube and the sub guide tube, respectively, so that the detection member is reliably guided forward and backward, and reliable insulation is ensured.

Since the insulating structure on the electrode body side is based on the main guide tube and the sub guide tube made of an insulating synthetic resin material, both guide tubes can be constructed of cylindrical members with a simple shape, which is effective in simplifying the structure. The main guide tube and the sub guide tube are fitted in the electrode body in a stationary state, and the main detection member and the sub detection member, which have a simplified shape, slide inside both guide tubes. Therefore, the forward and backward movements of both detection members are achieved smoothly, improving the operational reliability of the electrode.

When no part is present on the opposing electrode, the protruding secondary detection member is not pressed against the part when the electrode advances, so that the electrical circuit via the part as described above is not established, the absence of the part is detected, and the welding operation is reliably stopped.

3A and 3B are cross-sectional views of an electrode and a perspective view of a detection member. FIG. 4 is a partial cross-sectional view of the main sensing member. 4 is a cross-sectional view showing a joining structure between a main detection member and an auxiliary detection member. FIG.

Next, an embodiment of the electric resistance welding electrode of the present invention will be described.

1 to 3 show an embodiment of the present invention.

First, the parts will be described.

The part here is an iron projection bolt 1. It is composed of a shaft portion 2 with a male thread, a flat circular flange 3 integrated with the shaft portion 2, and a number of fusion bonding projections 4 provided on the flange surface on the shaft portion 2 side. Three fusion bonding projections 4 are provided on the same circle at 120 degree intervals. In the following explanation, the projection bolt may also be simply referred to as a bolt.

The fixed electrode 5 has a receiving hole 6 for the shaft portion 2. A flat steel plate part 7 is placed on the fixed electrode 5, and a pilot hole 8 formed in the steel plate part 7 is coaxially connected to the receiving hole 6. The bolt 1 is inserted into the pilot hole 8 and the receiving hole 6 by a retractable supply rod or manually by an operator.

Next, the electrode body will be described.

The electrode body 10 is made of a copper alloy conductive material such as chromium copper, and is cylindrical in shape and has a circular cross section. It is composed of a cylindrical first member 12, a cylindrical second member 13 , and a circular third member 14, which are connected to a forward/backward driving means 11 such as an air cylinder. The first member 12 and the second member 13 are integrated with a threaded portion 15, and the second member 13 and the third member 14 are integrated with a threaded portion 16. The electrode body 10 is formed with at least a large diameter hole 17 with a circular cross section and a small diameter hole 18 connected thereto. The large diameter hole 17 is provided in the first member 12 and the second member 13, and the small diameter hole 18 is provided in the third member 14. As described above, the electrode body 10 is a main component of the movable electrode.

Next, the guide tube will be described.

A main guide tube 20 made of an insulating synthetic resin material is fitted into the large diameter hole 17. A through hole 22 is provided in a bottom plate 21 of the main guide tube 20. For example, polytetrafluoroethylene (Teflon®) is used as the insulating synthetic resin material, and as other materials, synthetic resin materials having excellent heat resistance and wear resistance from among polyamide resins can also be used. A sub-guide tube 23 made of an insulating synthetic resin material is fitted into the small diameter hole 18. For example, polytetrafluoroethylene (Teflon®) is used as the insulating synthetic resin material, and as other materials, synthetic resin materials having excellent heat resistance and wear resistance from among polyamide resins can also be used.

The third member 14 is an end member of the electrode having a flat pressing end surface 24 formed thereon, and is designed to be replaced when the pressing end surface 24 becomes worn or deformed due to pressing. A communication hole 25 that opens at the center of the pressing end surface 24 and communicates with the auxiliary guide cylinder 23 is provided in the third member 14.

Next, the detection member will be described.

A main detection member 27 made of a conductive metal material and having a circular cross section is fitted slidably into the main guide tube 20. The main detection member 27 is formed of a cylindrical member, and a flat current-carrying end surface 19 is formed at its end. A sub-detection member 28 made of a conductive metal material and having a circular cross section, which is smaller in diameter than the main detection member 27 and is integrated with the main detection member 27, is fitted slidably into the sub-guide tube 23. The sub-detection member 28 is made of a round bar-shaped member. Stainless steel is used as the conductive metal material that constitutes the main detection member 27 and the sub-detection member 28. The main detection member 27 and the sub-detection member 28 are formed by cutting a single piece of material.

The inner diameter of the communication hole 25 is set to be larger than the diameter of the secondary detection member 28 , so that an insulating gap 26 is formed between the secondary detection member 28 and the communication hole 25 .

A cup-shaped insulating member 30 is fitted into the inner end portion, i.e., the deepest portion, of the large diameter hole 17, and a flat current-carrying terminal plate 31 made of a copper alloy is assembled inside the insulating member 30. A conducting wire 32 for the detection current is joined to the current-carrying terminal plate 31. The other conducting wire 33 is connected to the outer surface of the electrode body 10.

A compression coil spring 34 is inserted between the current-carrying terminal plate 31 and the current-carrying end surface 19, and its tension is received by the lower end surface of the main detection member 27 being pressed against the bottom plate 21. The compression coil spring 34 is seated on the flat current-carrying end surface 19 and the flat current-carrying terminal plate 31, so that good conductivity is achieved.

The length of the secondary detection member 28 is set so that in a standby state before the electrode advances, the secondary detection member 28 protrudes beyond the pressing end surface 24 of the electrode body 10. The protruding length is indicated by the symbol L.

A synthetic rubber O-ring 35 is fitted on the main detection member 27 to prevent impurities that may impair conductivity from reaching the conductive points of the compression coil spring 34.

In the above embodiment, the detection member, guide cylinder, etc. are assembled on the movable electrode side, but it is also possible to dispose these members on the fixed electrode side.

In the modified example shown in FIG. 2, a shallow recess 36 is provided in the end face of the main detection member 27, and a flat current-carrying end face 19 is formed therein, thereby preventing the compression coil spring 34 from slipping.

In the modified example shown in FIG. 3, the secondary detection member 28 is screwed and welded to the primary detection member 27 . The blackened areas are the welded portions 37 .

Next, the operation will be described.

1(A) shows a standby state in which the bolt 1 is inserted into the pilot hole 8 of the steel plate component 7 and the receiving hole 6 of the fixed electrode 5, with the secondary detection member 28 protruding. At this time, the secondary detection member 28 and the third member 14 are not electrically connected by the insulating gap 26. In other words, the main detection member 27 and the secondary detection member 28 are housed in the main guide tube 20 and the secondary guide tube 23, and since the insulating gap 26 is provided, the detection current that flows from the conductive line 32 through the compression coil spring 34 to the main detection member 27 and the secondary detection member 28 is not conducted to the electrode body 10.

When the electrode advances from this state, the tip of the secondary detection member 28 hits the flange 3, and the secondary detection member 28 moves relatively backward into the electrode body 10 while compressing the compression coil spring 34. Furthermore, as shown by the two-dot chain line in Figure 1 (A), when the electrode advances and the pressing end surface 24 hits the flange 3, the secondary detection member 28 and the electrode body 10 become conductive via the flange 3.

Therefore, a conductive circuit is formed which is made up of the conductive wire 32, the conductive terminal plate 31, the compression coil spring 34, the conductive end surface 19, the detection member consisting of the main detection member 27 and the sub detection member 28, the flange 3, the electrode body 10, and the other conductive wire 33. The passage of electricity through this conductive circuit serves as a trigger to pass a welding current.

If the bolt 1 is not fed for some reason, the state shown in Fig. 1(C) will be reached. The secondary detection member 28 will enter the pilot hole 8 or the receiving hole 6 while projecting, and the pressing end surface 24 will be in close contact with the steel plate part 7. In this state, the secondary detection member 28 and the electrode body 10 are not electrically connected due to the insulating gap 26, so no detection current will be passed. The bolt absence can be detected by various circuits, but it is preferable to use a timer. That is, the absence of the bolt 1 is detected by detecting the passage of a certain time after the electrode advancement as described above. As is clear from the above-mentioned operation of not passing the detection current, the diameter of the secondary detection member 28 is set smaller than the inner diameter of the pilot hole 8 or the receiving hole 6.

In the above operation, the detection current flows from the conductive line 32 to the conductive line 33. The direction of current flow may be reversed so that the current flows from the conductive line 33 to the conductive line 32.

The effects of the above-described first embodiment are as follows.

When the bolt 1 is held normally on the fixed electrode 5 side, the electrode advances so that the auxiliary detection member 28 and pressure end face 24 come into close contact with the flange 3, forming a conductive circuit consisting of the conductive wire 32, conductive terminal plate 31, compression coil spring 34, conductive end face 19, the detection member consisting of the main detection member 27 and auxiliary detection member 28, flange 3, electrode body 10, and conductive wire 33. This conductivity confirms that the bolt 1 is held normally on the fixed electrode 5 side, and this confirmation signal triggers the flow of welding current to complete the welding.

Since the detection member has a simplified structure formed by the main detection member 27 and the sub detection member 28, it can be easily manufactured by cutting a long and thin metal material and by joining the sub detection member 28 to the main detection member 27. By adopting the above-mentioned manufacturing method, conductivity from the main detection member 27 to the sub detection member 28 is ensured.

The main detection member 27 and the auxiliary detection member 28 made of conductive metal material can be shaped such that the main detection member 27 is cylindrical and the auxiliary detection member 28 is a round bar with a smaller diameter than the main detection member 27. This allows the metal detection members to have a simplified shape consisting of a large-diameter member and a small-diameter member. Furthermore, since the detection members of such a simplified shape are housed in the main guide tube 20 and the auxiliary guide tube 23 made of insulating synthetic resin material, the electrode body 10 contains a cylindrical member made of synthetic resin and a cylindrical or round bar-shaped member made of metal, simplifying the structure of the electrode as a whole.

Since the current-carrying end surface 19 formed on the end of the main detecting member 27 has a flat shape, the compression coil spring 34 is seated in a good contact state, and good electrical conductivity is achieved from the compression coil spring 34 to the main detecting member 27. The main detecting member 27 and the sub detecting member 28 slide respectively inside the main guide tube 20 and the sub guide tube 23, so that the advancement and retreat of the detecting members is reliably guided and reliable insulation can be ensured.

Since the insulating structure on the electrode body 10 side is made of the main guide tube 20 and the sub guide tube 23 made of an insulating synthetic resin material, both guide tubes 20, 23 can be constructed of cylindrical members of a simple shape, which is effective in simplifying the structure. The main guide tube 20 and the sub guide tube 23 are fitted in the electrode body 10 in a stationary state, and the main detection member 27 and the sub detection member 28, which have a simplified shape, slide inside both guide tubes 20, 23. Therefore, the forward and backward movements of both detection members 27, 28 are smoothly achieved, improving the operational reliability of the electrode.

When there is no bolt 1 on the fixed electrode 5 side, the protruding secondary detection member 28 is not pressed against the flange 3 when the electrode advances, so that the above-mentioned electrical circuit via the flange 3 is not established, the absence of the bolt is detected, and the welding operation is reliably stopped.

As described above, the electrode of the present invention improves electrical conductivity to the reciprocating detection member, simplifies the structure, and improves productivity and operational durability. Therefore, it can be used in a wide range of industrial fields, such as automobile body welding processes and sheet metal welding processes for home electrical appliances.

REFERENCE SIGNS LIST 1 Part, projection bolt 2 Shaft 3 Flange 5 Fixed electrode 6 Receiving hole 7 Steel plate part 8 Pre-hole 10 Electrode body 12 First member 13 Second member 14 Third member 17 Large diameter hole 18 Small diameter hole 19 Current-carrying end surface 20 Main guide tube 23 Sub-guide tube 24 Pressurizing end surface 25 Communication hole 26 Insulating gap 27 Main detection member 28 Sub-detection member 31 Current-carrying terminal plate 32 Conducting wire 33 Conducting wire 34 Compression coil spring L Projection length

Claims (1)

an electrode body having a circular cross section and made of a conductive metal material, the electrode body being composed of a first member connected to a forward/backward driving means such as an air cylinder, a second member connected to the first member via a threaded portion, and a third member connected to the second member via a threaded portion and having a flat pressing end surface;
A large diameter hole is formed in the first member and the second member,
A small diameter hole is formed in the third member,
a main guide tube which is a tubular member made of insulating synthetic resin material and has a circular cross section is fitted into the large diameter hole of the second member and the main guide tube is fixed to the electrode body, and an auxiliary guide tube which is a tubular member made of insulating synthetic resin material and has a circular cross section is fitted into a small diameter hole formed in the third member and has a diameter smaller than the large diameter hole, and the auxiliary guide tube is fixed to the electrode body, so that the inner surface of the large diameter hole of the second member and the inner surface of the small diameter hole of the third member are covered by the main guide tube and the auxiliary guide tube,
A main detection member made of a conductive metal material and having a circular cross section is slidably fitted in the main guide tube,
a secondary detection member having a circular cross section and a smaller diameter than the primary detection member and made of a conductive metal material and integrated with the primary detection member, the secondary detection member being fitted in the secondary guide tube in a slidable state;
In a standby state before the advancing operation, the length of the secondary detection member is set so as to protrude beyond the pressing end face of the electrode body,
A flat conductive end surface that improves electrical conductivity to the main detection member is formed at the end of the main detection member by an end surface of the main detection member itself;
a compression coil spring is inserted between an electrically conductive terminal plate disposed in an insulated state at an inner end of the large diameter hole in the first member and an electrically conductive end face of the main detection member;
The device is configured such that three members, namely, a first member in which an electric terminal plate is disposed, a second member in which a main guide tube is fitted and in which a main detection member and a compression coil spring are inserted, and a third member in which a sub-guide tube through which a sub-detection member passes is fitted , are integrated via a screw portion;
The main guide tube has an open shape on the first member side and a bottom plate on the third member side with a through hole through which the secondary detection member passes.
The thickness of the main guide cylinder and the thickness of the bottom plate of the main guide cylinder are set to be approximately the same thickness dimension,
When the third member is integrated with the second member via the screw portion, an end of the auxiliary guide tube is configured to come into contact with the bottom plate;
1. An electric resistance welding electrode, comprising: a conductive terminal plate and an electrode body, the conductive wire for detecting a current being connected to the conductive terminal plate and the electrode body.

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