JP2023077361A - Electrode for electrical resistance welding - Google Patents

Abstract

To effectively cool a stopper member having a magnet built-in in direct contact with cooling air and to simplify an intermittent structure of the cooling air.SOLUTION: An insertion hole 8 is formed in an end lid 6 of an electrode body 5, a guide cylinder 13 is inserted into the electrode body 5, a guide hole 14 of the guide cylinder 13 is composed of a large-diameter hole 15 and a small-diameter hole 16, a stopper member 17 having a large-diameter part 18 and a small-diameter part 19 is provided, a stopper surface 21 is formed in the stopper member 17, a magnet 20 for attracting a shaft-shaped component 1 to the stopper surface 21 is stored in the stopper member 17 via the small-diameter part 19, and air passages 25 and 26 are formed in the large-diameter part 18 and the small-diameter part 19 of the stopper member 17. A movable end surface 27 formed in the stopper member 17 is sealed to or separated from the static inner end surface 28 of the guide hole 14, thereby forming a distribution of cooling air to be intermittent. A vent hole 32 for supplying the cooling air to the large-diameter hole 15 is provided in the electrode body 5.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an electric resistance welding electrode in which a stopper member containing a magnet is accommodated in an electrode body, and the stopper member is cooled with cooling air.

WO2004/009280 describes that a magnet is housed in a stopper member composed of a large-diameter portion and a small-diameter portion, and the magnet is cooled by water cooling.

Japanese Patent Laying-Open No. 2011-183414 describes that a magnet is housed in a stopper member composed of a large-diameter portion and a small-diameter portion, and the stopper member housed in the electrode body is pressed by the tension of a compression coil spring or air pressure. It is This publication makes no mention of a method for cooling the stopper member.

Japanese Patent Laying-Open No. 2017-006982 describes that a movable end face and a stationary inner end face are formed on a synthetic resin sliding portion integrated with a guide pin to interrupt cooling air flow.

WO2004/009280 JP 2011-183414 A JP 2017-006982 A

The stopper member in Patent Document 1 is housed in a guide tube made of synthetic resin, and the stopper member is cooled by flowing cooling water through cooling water passages provided on the outer peripheral side of the guide tube. With such a cooling method, the cooling water flow does not directly contact the stopper member, so there is a problem that it is difficult to improve the cooling performance. In addition, it is difficult to establish a seal structure for the cooling water channel if the cooling water is brought into direct contact with the stopper member.

The stopper member in Patent Document 2 is built in the electrode, and there is no concept of depriving the welding heat of the stopper member with a cooling fluid such as cooling water or cooling air. Although Patent Document 2 describes applying compressed air to the upper surface of the stopper member instead of using a coil spring, this only relates to pressurizing means and does not suggest air cooling.

FIG. 4 described in Patent Document 2 is reprinted in the drawings of the present application. It is shown in FIG. Here, the wires connected to the terminal plate 27 in the cup member 26 are indicated by solid lines, and the tubular mouthpieces for receiving the wires are illustrated, but this has nothing to do with the inflow of cooling air. It is a member. Further, paragraph 0033 of Patent Document 2 states that "in place of the coil spring 28, compressed air may act as an air spring on the upper surface of the stopper member 21." This is meant as an air spring, not the idea that O-rings are also incorporated to flow the cooling air. It should be noted that the numbers of the members attached to FIG. 4 have nothing to do with the numbers of the embodiment drawings of the present invention.

The cooling in Patent Document 3 is mainly air cooling for the sliding portion made of synthetic resin, not cooling of the stopper member as in the present invention.

As described above, the techniques disclosed in each of the patent documents do not prevent overheating of the magnet by bringing the cooling air into direct contact with the stopper member containing the magnet. Patent Document 1 describes a structure in which the stopper member is indirectly water-cooled and the cooling performance is difficult to improve. In Patent Document 2, no cooling fluid is applied to the stopper member. Patent document 3 does not disclose the stopper member itself in which the magnet is built.

SUMMARY OF THE INVENTION The present invention has been provided to solve the above-mentioned problems. The purpose is to simplify the structure.

The invention according to claim 1,
An end cover in which an insertion hole for a shaft-shaped part is formed is attached to a cylindrical electrode body made of a copper alloy,
A guide cylinder made of a heat insulating material is inserted into the electrode body,
the guide hole provided in the guide tube is composed of a large diameter hole and a small diameter hole communicating with the insertion hole,
A stopper member having a large-diameter portion having a circular cross-section and being inserted in the large-diameter hole in a retractable state and a small-diameter portion having a circular cross-section and being inserted in the small-diameter hole in a retractable state is provided,
a tip surface of the small-diameter portion of the stopper member serves as a stopper surface for receiving a shaft-shaped component inserted into the small-diameter hole,
a magnet that attracts the shaft-like part to the stopper surface via the small-diameter portion is accommodated in the stopper member;
an air passage is formed between the large-diameter portion of the stopper member and the guide hole;
an air passage is formed between the small diameter portion of the stopper member and the guide hole;
A movable end face formed at the boundary between the large diameter portion and the small diameter portion of the stopper member is in close contact with a stationary inner end face formed at the boundary between the large diameter hole and the small diameter hole of the guide hole. By moving away from the stopper member, the circulation of the cooling air is interrupted so that the cooling air circulates while being in direct contact with the surface of the stopper member,
The electrode for electric resistance welding is characterized in that the electrode main body is provided with a vent for supplying cooling air to the large diameter hole.

When the shaft-shaped part is inserted into the insertion hole of the end cover, the shaft-shaped part is firmly attracted to the small-diameter part of the stopper member by the magnetic attraction force that reaches the stopper surface through the small-diameter part, and remains in a stable stationary state. Become. Here, when the mating electrode advances and the shaft-like part is pushed down, the movable end surface of the stopper member separates from the stationary inner end surface of the guide hole, and cooling air flows through the air passages arranged in the large diameter portion and the small diameter portion respectively. Welding current is applied during the flow cooling of the cooling air, and heat is generated from the melted portion. The heat of fusion is transferred from the steel plate component to the shaft portion, and further transferred from the shaft portion to the stopper member. In addition, heat is transferred from the electrode main body to the stopper member through the guide tube. Therefore, the outer peripheral surface of the stopper member is directly cooled by the cooling air flow, and welding heat transmitted to the magnet is suppressed.

That is, since the cooling air flows while being in direct contact with the surface of the stopper member, good magnet protection can be obtained due to the high air cooling effect. In other words, when the magnet reaches an abnormally high temperature, it reaches the temperature demagnetization region, and in the worst case, reaches irreversible demagnetization, which impairs the attraction stability of the shaft-like part. Abnormal heating of the magnet is prevented by flowing the cooling air in direct contact with the surface of the stopper member.

A water-cooled system requires a structure for separating the housing space for the stopper member from the cooling water circulation space, for example, a member such as a watertight partition plate, which complicates the structure. Then, even if the cooling air is blown directly onto the stopper member, there is no adverse effect on the surrounding members, so that the structure can be simplified and troubles due to air leakage can be avoided.

If even a small amount of cooling water for cooling the stopper member leaks, it will adversely affect neighboring members. However, with an air-cooled system, even a small amount of air leakage will have little adverse effect on neighboring components, so the line will not stop suddenly, and continuous operation will be possible. Thus, it becomes possible to reduce the economic loss.

A movable end face is formed at the boundary between the large-diameter portion and the small-diameter portion of the stopper member, and a stationary inner end face is formed at the boundary between the large-diameter hole and the small-diameter hole of the guide hole. is formed on the stopper member itself, which is advantageous for structural simplification.

If spatter scatters during melting, it may be attracted by the magnet in the stopper member and contaminate the inside of the electrode. As for the order, since the welding current is applied after the cooling air starts to flow, the spatter that is about to scatter toward the stopper member is forcibly pushed back under the adverse wind, which is also effective in dealing with the spatter. be.

It is sectional drawing of the whole electrode, and sectional drawing of a partial location. 2A-2A cross-section and 2B-2B cross-section of FIG. 1; FIG. FIG. 10 is a cross-sectional view showing a modification of the air passage; It is a perspective view of a stopper member. FIG. 4 is a cross-sectional view reproduced from FIG. 4 of Patent Document 2;

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the electrode for electric resistance welding of this invention is demonstrated.

1-4 illustrate embodiments of the present invention.

First, the shaft-like part will be explained.

As shaft-like parts, there are various things such as projection bolts and rotation shafts of rotating parts. Here, projection bolts are the object of welding. As described above, there are various types of parts to be welded. In the following description, projection bolts may be simply referred to as bolts.

A projection bolt 1 made of iron includes a shaft portion 2 having a male thread, a disk-shaped flange 3 integrated with the shaft portion 2, and welding protrusions provided on the surface of the flange 3 on the side of the shaft portion 2. 4. The welding projections 4 are arranged near the outer circumference of the flange 3, and are provided at three intervals of 120 degrees.

Next, the electrode body will be explained.

The electrode body 5 has a cylindrical shape and is made of a copper alloy such as chromium copper. An end cap 6 made of a copper alloy such as beryllium copper is connected to the end of the electrode body 5 via a threaded portion 7 . The end cover 6 is provided with an insertion hole 8 into which the shaft portion 2 of the bolt 1 is inserted, and an insulating cylinder 9 made of an insulating material is provided in a part of the hole. A fixing portion 11 is coupled to the other end portion side of the electrode main body 5 via a screw portion 10 . The fixed portion 11 is coupled to the stationary member 24 by taper fitting or the like.

Polytetrafluoroethylene (trade name: Teflon, registered trademark), polyamide resin, or the like is used as an insulating material for the insulating tube 9, the guide tube 13, and an insulating sheet 29, which will be described later.

Next, the guide cylinder will be explained.

A guide cylinder 13 having a circular cross section is inserted into the electrode body 5 by a method such as press fitting. A guide hole 14 formed in the guide tube 13 is composed of a large-diameter hole 15 and a small-diameter hole 16 communicating with the insulating tube 9 and the insertion hole 8 . A fixing pin 23 made of synthetic resin is driven in to prevent the guide tube 13 from being displaced.

Next, the stopper member will be explained.

The stopper member 17 has a large diameter portion 18 which has a circular cross section and is inserted into the large diameter hole 15 so as to be able to move forward and backward, and a large diameter portion 18 which has a circular cross section and is inserted into the small diameter hole 16 so that it can move forward and backward. It is constituted by a small diameter portion 19 that

As shown in FIG. 1B, the large-diameter portion 18 of the stopper member 17 is made of a nonmagnetic material such as stainless steel and has a cup-like vessel shape. A magnet 20 is housed therein. This magnet 20 is a permanent magnet. The small-diameter portion 19 is made of iron with good magnetic permeability, and its tip surface serves as a stopper surface 21 for receiving the shaft portion 2 . Welding is desirable for integrating the small diameter portion 19 and the large diameter portion 18 . The welded portion 22 is shown blackened, and the surface is finished smoothly after welding. The state is such that the container-shaped large diameter portion 18 is sealed with the small diameter portion 19 , and the magnet 20 is in close contact with the lower surface of the small diameter portion 19 . The magnet 20 may be vertically embedded and arranged as indicated by a two-dot chain line in FIG. 1(B).

When the shaft portion 2 is inserted into the insertion hole 8 and the tip of the shaft portion 2 is received by the stopper surface 21 , the attractive force of the magnet 20 acts on the shaft portion 2 , and the shaft portion 2 is firmly attracted to the stopper surface 21 . be done.

Next, the air passage will be explained.

An air passage 25 is formed between the large diameter portion 18 of the stopper member 17 and the guide hole 14, that is, between the large diameter hole 15, and between the small diameter portion 19 of the stopper member 17 and the guide hole 14, that is, the small diameter hole 16. An air passage 26 is formed between them. Air passages 25 and 26 are annular gaps, as shown in FIG. In addition, in FIG. 1C, the pear-skin pattern and hatching indicating the cross section are omitted for easy viewing.

A movable end surface 27 formed at the boundary between the large diameter portion 18 and the small diameter portion 19 of the stopper member 17 is in close contact with the stationary inner end surface 28 formed at the boundary between the large diameter hole 15 and the small diameter hole 16 of the guide hole 14. It is configured to intermittently flow the cooling air by moving to and from it. The movable end face 27 and the stationary inner end face 28 are present on a virtual plane perpendicularly crossing the center axis OO of the electrode.

A vent 32 is provided in the electrode body 5 to supply cooling air to the air passage 25 and an air supply tube 37 extending from an air pump (not shown) is connected to the vent 32 .

An insulating sheet 29 is fitted to the inner bottom surface of the electrode main body 5, and a conducting plate 30 is fixed thereon. A compression coil spring 31 is fitted between the lower surface of the stopper member 17 and the current-carrying plate 30, and the movable end surface 27 is pressed against the stationary inner end surface 28 by the tension of the spring. This compression inhibits the flow of cooling airflow.

As shown in FIG. 1C, the clearance of the air passage 25 is indicated by L1, and the clearance of the air passage 26 is indicated by L2. A clearance (so-called valve opening clearance) when the movable end surface 27 is separated from the stationary inner end surface 28 is indicated by L3. The flow area of the air passage 25, the flow area of the air passage 26, and the flow area of the clearance L3 are set to be substantially equal. As a result, the circulation of the cooling air becomes smoother, and a less turbulent cooling air flow can be obtained by reducing the flexibility of the air passage.

As is clear from FIG. 2, the diameter of the air passage 25 is larger than the diameter of the air passage 26, so if the air passages 25 and 26 have substantially the same flow area, the clearance L1 is greater than the clearance L2. be larger than

The gap distance of the air passage is L1>L2, but in order to further reduce the flexibility of the air passage, L3>L1>L2. By doing so, the degree of curvature of the air flow is reduced, the turbulence is reduced, the flow rate of the cooling air is increased, and the cooling effect can be further enhanced.

When a force acts on the stopper member 17 in an oblique direction, the clearance L2<L1 is satisfied so that the clearance L2 is small and the outer peripheral surface of the large-diameter portion 18 closes to the large-diameter hole 15 at an early stage. Since it hits the inner peripheral surface, the inclination angle of the stopper member 17 can be kept small, it is possible to reduce the misalignment of the shaft portion 2 with respect to the central axis OO, and the deterioration of welding quality can be prevented.

As shown in FIG. 1A, in a state where the lower end of the shaft portion 2 of the bolt 1 is attracted to the stopper surface 21, a space L4 is provided between the welding projection 4 and the steel plate component 12. This space L4 is widened, the clearance L3 between the movable end surface 27 and the stationary inner end surface 28 is also widened. A pilot hole is formed in the steel plate part 12 , and the shaft portion 2 is inserted into the pilot hole and the insertion hole 8 . Further, the steel plate component 12 is placed on the end cover 6 , and the mounting position of the steel plate component 12 is determined by a robot device or the like so that the prepared hole is coaxial with the insertion hole 8 .

Next, modified examples of the air passage will be described.

FIG. 3 is a cross-sectional view corresponding to the cross-section taken along line 2A-2A in FIG. The aforementioned air passages 25 and 26 are annular spaces, but this modification is formed by processing the small-diameter portion 19 of the stopper member 17 . The small-diameter portion 19 is inserted in the small-diameter hole 16 in a substantially gap-free and slidable state. A flat surface 39 extending in the direction of the central axis OO is formed on the outer surface of the small-diameter portion 19 , and an air passage 40 is formed between the flat surface 39 and the arc-shaped inner surface of the small-diameter hole 16 . The planes 39 are provided at intervals of 90 degrees, and four air passages 40 are provided.

Although not shown, an air passage structure similar to that of FIG. 3 is adopted also on the large diameter portion 18 side.

The above-mentioned "..the state in which there is substantially no gap and is slidable.." It means a state in which there is no feel and the sliding in the direction of the center axis OO is possible.

Next, the energizing circuit will be explained.

In this embodiment, it can be checked whether the bolt 1 is inserted into the insertion hole 8 or not. A signal line 33 joined to the current-carrying plate 30 and a signal line 34 joined to the electrode main body 5 are provided. When the bolt 1 is normally inserted into the insertion hole 8 , a detection current flows from the detection device 35 to the electrode main body 5 via the signal line 34 . A detection current flows into the detection device 35 through the end cap 6 , the steel plate part 12 , the shaft portion 2 , the stopper member 17 , the compression coil spring 31 , the current-carrying plate 30 and the signal line 33 . The detection device 35 detects the detection current and uses it as a trigger signal to advance the movable electrode 36 .

The effects of the embodiment described above are as follows.

When the bolt 1 is inserted into the insertion hole 8 of the end cover 6, the bolt 1 is firmly attracted to the small diameter portion 19 of the stopper member 17 by the magnetic attractive force reaching the stopper surface 21 through the small diameter portion 19, and is stabilized. to a stationary state. Here, when the mating electrode 36 advances and the bolt 1 is pushed down, the movable end face 27 of the stopper member 17 separates from the stationary inner end face 28 of the guide hole 14, and the air passages arranged in the large diameter portion 18 and the small diameter portion 19 respectively. Cooling air flows through 25,26. Welding current is applied during the flow cooling of the cooling air, and heat is generated from the melted portion. The heat of fusion is transferred from the steel plate component 12 to the shaft portion 2 and further transferred from the shaft portion 2 to the stopper member 17 . In addition, heat is transferred from the electrode main body 5 to the stopper member 17 via the guide tube 13 . Therefore, the outer peripheral surface of the stopper member 17 is directly cooled by the cooling airflow, and welding heat transferred to the magnet 20 is suppressed.

That is, since the cooling air flows while being in direct contact with the surface of the stopper member 17, good protection of the magnet can be obtained due to the high air cooling effect. In other words, when the magnet 20 reaches an abnormally high temperature, it reaches the temperature demagnetization region, and in the worst case, reaches irreversible demagnetization, which impairs the attraction stability of the bolt 1 . Abnormal heating of the magnet 20 is prevented by circulating cooling air in direct contact with the surface of the stopper member 17 .

Immediately after welding a normal number of bolts, for example, 4 bolts per minute to the steel plate part 12, the bolt 1 was manually pulled out from the insertion hole 8 together with the steel plate part 12. It had to be pulled slightly. Therefore, it was confirmed that the attraction force with which the bolt 1 is attracted to the stopper surface 21 is a sufficient value. In actuality, it is structurally impossible to measure the magnet temperature immediately after welding, so the pull-out test method was used to confirm changes in the attractive force. If the magnet 20 is heated to an abnormally high temperature, it will reach the irreversible demagnetization range and the attractive magnetic force will decrease. is deemed to have been properly fulfilled.

In the case of the water-cooled type, a structure for distinguishing the housing space of the stopper member 17 from the circulation space of the cooling water, for example, a member such as a watertight partition plate is required, which complicates the structure. With this formula, even if the cooling air is blown directly onto the stopper member 17, there is no adverse effect on the surrounding members, so the structure can be simplified and troubles due to air leakage can be avoided.

If even a small amount of cooling water for cooling the stopper member 17 leaks, it will adversely affect neighboring members. However, with an air-cooled system, even a small amount of air leakage will have little adverse effect on neighboring components, so the line will not stop suddenly, and continuous operation will be possible. Thus, it becomes possible to reduce the economic loss.

A movable end face 27 is formed at the boundary between the large diameter portion 18 and the small diameter portion 19 of the stopper member 17, and a stationary inner end face 28 is formed at the boundary between the large diameter hole 15 and the small diameter hole 16 of the guide hole 14. Part of the cooling air intermittent structure is formed in the stopper member 17 itself, which is advantageous for structural simplification.

If spatter scatters during melting, it may be attracted to the magnet 20 in the stopper member 17 and contaminate the inside of the electrode. In order, since the welding current is applied after the cooling air starts to flow, the spatter that is about to scatter toward the stopper member 17 is forcibly pushed back under the adverse wind, which is also effective in dealing with the spatter. is.

By making the flow area of the air passage 25 on the large diameter portion 18 side, the air passage 26 on the small diameter portion 19 side, and the air passage by separating the movable end face 27 from the stationary inner end face 28, substantially the same size. , the circulation state of the cooling air can be made smooth, and the flow rate of the cooling air can be easily increased, which is suitable for improving the cooling effect. In addition, by setting the separation width of the movable end face away from the stationary inner end face to a large value, the bending flow of the cooling air flow is reduced, the pressure loss due to the bending of the flow path is reduced, and the contact of the cooling air with the stopper member is minimized. can improve sexuality.

As in the above-described embodiment, an annular air passage 25 is provided between the outer peripheral surface of the large diameter portion 18 of the stopper member 17 and the inner peripheral surface of the large diameter hole 15 of the guide hole 14 . When an annular air passage 26 is provided between the outer peripheral surface of the small diameter portion 19 and the inner peripheral surface of the small diameter hole 16 of the guide hole 14, the air passage gap L1 on the side of the small diameter hole 16 is replaced by the large diameter hole. By setting it larger than the air passage gap L2 on the 15 side, the passage areas of both the air passages 25 and 26 can be made substantially the same. At the same time, by selecting the distance L3 by which the movable end face 27 of the stopper member 17 is separated from the stationary inner end face 28 of the guide hole 14, the flow passage area of the cooling air at this separated portion is adjusted to the flow passage of the annular air passages 25 and 26. area can be approximately the same. Therefore, the cooling air flowing along the outside of the stopper member 17 becomes a smooth air flow with little turbulence, and the surface of the stopper member 17 is effectively cooled.

As described above, according to the electrode of the present invention, the cooling air is brought into direct contact with the stopper member containing the magnet for effective cooling, and the intermittent structure of the cooling air is simplified. . Therefore, it can be used in a wide range of industrial fields, such as automobile body welding processes and home electric appliance sheet metal welding processes.

1 Projection bolt, shaft-like part 2 Shaft part 3 Flange 4 Welding projection 5 Electrode body 6 End cover 8 Insertion hole 12 Steel plate part 13 Guide cylinder 14 Guide hole 15 Large diameter hole 16 Small diameter hole 17 Stopper member 18 Large diameter part 19 Small diameter Portion 20 Magnet 21 Stopper surface 25 Air passage 26 Air passage 27 Movable end surface 28 Stationary inner end surface 32 Ventilation port 40 Air passage L1 Gap interval L2 Gap interval L3 Gap interval L4 Gap between welding projection and steel plate component OO Central axis line

Claims (1)

An end cover in which an insertion hole for a shaft-shaped part is formed is attached to a cylindrical electrode body made of a copper alloy,
A guide cylinder made of a heat insulating material is inserted into the electrode body,
the guide hole provided in the guide tube is composed of a large diameter hole and a small diameter hole communicating with the insertion hole,
A stopper member having a large-diameter portion having a circular cross-section and being inserted in the large-diameter hole in a retractable state and a small-diameter portion having a circular cross-section and being inserted in the small-diameter hole in a retractable state is provided,
a tip surface of the small-diameter portion of the stopper member serves as a stopper surface for receiving a shaft-shaped component inserted into the small-diameter hole,
a magnet that attracts the shaft-like part to the stopper surface via the small-diameter portion is accommodated in the stopper member;
an air passage is formed between the large-diameter portion of the stopper member and the guide hole;
an air passage is formed between the small diameter portion of the stopper member and the guide hole;
A movable end face formed at the boundary between the large diameter portion and the small diameter portion of the stopper member is in close contact with a stationary inner end face formed at the boundary between the large diameter hole and the small diameter hole of the guide hole. By moving away from the stopper member, the circulation of the cooling air is interrupted so that the cooling air circulates while being in direct contact with the surface of the stopper member,
An electrode for electric resistance welding, wherein a vent hole for supplying cooling air to the large-diameter hole is provided in the electrode body.

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