JP7108251B2 - Electric resistance welding electrodes for cap nuts - Google Patents

Description

The present invention relates to an electric resistance welding electrode for welding a cap nut in which a cover member is integrated with a nut body.

The electric resistance welding electrode described in Japanese Patent Application Laid-Open No. 2011-183414 includes a shaft portion having a male thread, a circular flange integrated with the shaft portion, and a welding projection formed on the surface of the flange. The bolt is the object of welding. In this electrode, it is described that the electrode is advanced while the shaft portion is inserted into the receiving hole, and the bolt is welded to the steel plate component by pressing the flange surface with the tip surface of the electrode.

JP 2011-183414 A

In projection bolt welding as described above, since the flange surface is pressurized, the contact area between the electrode tip surface and the flange surface can be set large. pressure can be exerted on the bolt. In particular, even if the bolt is displaced in the diametrical direction, the electrode pressurizing force can be applied normally. This diametrical deviation requires a large gap between the outer diameter of the shaft and the inner diameter of the receiving hole to smoothly insert the shaft into the insertion hole because the shaft has a male thread. , the amount of eccentricity inevitably increases.

However, in a cap nut having a structure in which a cover member is integrated with the nut body, it is not possible to increase the contact area between the electrode tip surface and the nut body. If this is the case, the pressure applied to the nut body will act in a biased state, and there is the problem that normal welding cannot be ensured. In addition, since the mass of the nut body is much larger than the mass of the cover member, there is a problem that the nut is held in the receiving hole of the electrode unstable.

SUMMARY OF THE INVENTION The present invention has been provided to solve the above problems, and an object of the present invention is to ensure that the nut is stably held in the receiving hole of the electrode by utilizing the unique shape of the cap nut.

The invention according to claim 1,
A cap nut in which a welding projection is provided on one end face of a nut body and a cover member having a cylindrical portion is integrated on the other end face, and is intended to be welded to a steel plate part,
A narrow annular pressurized surface is formed at the boundary between the nut body and the cover member,
The cylindrical portion has a cylindrical surface with a straight and smooth surface,
An electrode body having a circular cross section and a cylindrical shape is configured using a metal material,
A pressurizing member coupled to the end of the electrode body is formed with a pressurizing surface that is in close contact with the surface to be pressurized, and is formed with a receiving hole into which the cylindrical portion of the cover member is inserted. and the outer surface of the cylindrical portion is substantially zero, and the cylindrical portion slides against the receiving hole,
A guide cylinder made of an insulating material and formed with a large diameter hole and a small diameter hole is inserted into the electrode main body,
The stopper member is composed of a large-diameter portion in which the permanent magnet is accommodated and a small-diameter portion for attracting the cap nut by the attraction force of the permanent magnet,
The large-diameter portion of the stopper member is slidably inserted into the large-diameter hole of the guide cylinder, and the small-diameter portion of the stopper member is slidably inserted into the small-diameter hole of the guide cylinder. ,
A gap is formed between the small-diameter portion and the receiving hole by making the diameter of the small-diameter portion smaller than the inner diameter of the receiving hole,
The length of the small diameter portion is set so that the stopper surface formed on the tip end surface of the small diameter portion is positioned in the middle of the receiving hole and receives the cover member . It is an electric resistance welding electrode.

When the cover member is inserted into the receiving hole of the pressure member, the attractive force of the permanent magnet acts on the cover member through the small diameter portion, the cover member is pulled into the receiving hole, and the tip portion of the cover member touches the stopper surface. be adsorbed. At this stage, a slight gap is formed between the pressure surface of the pressure member and the nut body. Then, when the electrode advances while the cover member is held in a state of being attracted to the stopper surface, the welding projection of the nut body is pressed against the steel plate component. As the pressing progresses further, this pressing reaction force acts to press the stopper member relatively, and the pressing surface of the pressing member comes into close contact with the nut body. Welding current is applied in this state, and welding is completed.

The cylindrical portion of the cover member is a cylindrical member having a straight cylindrical surface and a smooth surface. It is possible to greatly reduce the air gap and minimize the amount of deviation of the cap nut from the central axis of the electrode. In other words, the gap between the inner surface of the receiving hole and the outer surface of the cylindrical portion is substantially zero, and the fitting degree of the cover member can be reduced in a so-called sliding state in which the cover member can be inserted into or pulled out of the receiving hole. As a result, the cap nut is held coaxially with respect to the central axis of the electrode, the relative positions of the nut body and the pressing surface of the pressing member are accurately set, and the pressing surface is the pressed surface of the nut body. Contact is made over the entire circumference, and the pressurizing force of the pressurizing surface against the pressurized surface acts on the nut body without being biased, so that the welded state of each welding projection is uniformly good over the entire area, improving welding quality. .

As a feature of the shape of the cap nut, since the nut body and the cover member are integrated, the length in the axial direction is significantly longer than that of a normal projection nut. That is, they are taller. For this reason, if some lateral external force acts on the front end of the cover member after welding, the welded portion may peel off or break, increasing the inclination of the entire cap nut. Such an inclination is due to variations in the molten state of the welding projections because the pressure surface of the pressure member is not uniformly in contact with and pressurized against the pressure-receiving surface of the nut body over the entire circumference. is the cause. In order to avoid such a problem, it is essential that the pressing surface of the pressing member uniformly contacts and pressurizes the pressed surface of the nut body over the entire circumference. Due to such a normal contact state, the cap nut is maintained coaxially or almost coaxially with the central axis of the electrode, so that the pressure surface is positioned relative to the surface to be pressed, as shown in FIG. 2(B). Contact is made over the entire area, and a uniform pressure load is applied to the steel plate parts of each welding projection. Therefore, even with a tall cap nut, strong welding can be ensured without tilting to the steel plate component.

Since the length of the small diameter portion is set so that the stopper surface of the small diameter portion is positioned within the receiving hole, the cover member is inserted into the receiving hole and remains surrounded by the receiving hole. The suction of the cover member is stopped by a stopper surface standing by in the middle of the longitudinal direction. In this manner, a suction force acts on the cover member within the receiving hole, and the cylindrical portion of the cover member is inserted into the receiving hole with substantially no clearance. Therefore, even if some external force acts on the lower portion of the cap nut in the diametrical direction, the pivotal displacement of the cap nut with respect to the central axis of the electrode can be reduced to a level that does not cause actual damage. This ensures proper welding.

Since the length of the small-diameter portion is set so that the stopper surface formed on the tip surface of the small-diameter portion is positioned within the receiving hole, the length of the small-diameter portion can be made as long as possible, and the permanent It is possible to improve the durability of the permanent magnet by reducing the amount of heat transferred to the magnet.

A cap nut in which a welding projection is provided on one end face of a nut body and a cover member having a cylindrical portion is integrated on the other end face, and is intended to be welded to a steel plate part,
An electrode body having a circular cross section and a cylindrical shape is configured using a metal material,
a receiving hole into which the cylindrical portion of the cover member and the nut body are inserted is formed in the pressure member coupled to the end portion of the electrode body;
A guide cylinder made of an insulating material and formed with a large diameter hole and a small diameter hole is inserted into the electrode main body,
The stopper member is composed of a large-diameter portion in which the permanent magnet is accommodated and a small-diameter portion for attracting the cap nut by the attraction force of the permanent magnet,
The large-diameter portion of the stopper member is slidably inserted into the large-diameter hole of the guide cylinder, and the small-diameter portion of the stopper member is slidably inserted into the small-diameter hole of the guide cylinder. ,
The length of the small-diameter portion is set so that the stopper surface formed on the tip surface of the small-diameter portion is located in the vicinity of the opening end of the small-diameter hole.

Since the cylindrical portion of the cover member and the nut body are inserted into the receiving hole, the entire cap nut is held in the receiving hole, thereby improving holding stability of the cap nut. Since the length of the small-diameter portion is set so that the stopper surface formed on the tip surface of the small-diameter portion is located near the opening end of the small-diameter hole, the length of the small-diameter portion can be shortened. It is possible to make the attraction force of the permanent magnet act on the cap nut more strongly, and the holding stability of the cap nut is improved.

FIG. 2 is a cross-sectional view of an electrode in its entirety and relevant parts; It is the top view and sectional drawing of a cap nut. FIG. 11 is a cross-sectional view showing another embodiment;

Below, the form for implementing the electric resistance welding electrode for cap nuts of this invention is demonstrated.

1 and 2 show Example 1 of the present invention.

First, the electrode body will be described.

The electrode body 1 made of a copper alloy conductive metal material such as chromium copper has a cylindrical shape and a circular cross section. This electrode main body 1 is a movable electrode, and is integrated with a coupling member 2 of forward/backward driving means such as an air cylinder (not shown) by taper fitting or the like.

The electrode main body 1 includes a cylindrical base member 3 connected to a connecting member 2 and a cylindrical connecting member 4 which are integrated with a screw portion 5 . A cylindrical guide tube 8 made of an insulating material and having a large-diameter hole 6 and a small-diameter hole 7 formed therein is inserted into the electrode body 1, which is the connection member 4 here. A pressure member 9 is coupled to the end of the electrode body 1 by a threaded portion 10 . A receiving hole 12 is formed through the pressing member 9, and a cap nut, which will be described later, is inserted therein. A flat pressure surface 11 is formed on the tip surface of the pressure member 9 . A central axis OO of the electrode is perpendicular to the pressure surface 11 . As the synthetic resin material for the guide cylinder 8, any material having excellent heat resistance and abrasion resistance may be used, and it is desirable to use polytetrafluoroethylene (trade name: Teflon, registered trademark). As another material, it is also possible to adopt a resin excellent in heat resistance and wear resistance from among polyamide resins.

Next, the cap nut will be explained.

The cap nut 20 is made of iron and is composed of a nut body 13 and a cover member 16 . A threaded hole 14 is formed in the nut body 13, and a welding projection 15 is provided on one end face. Three welding projections 15 are provided at intervals of 120 degrees on the same circumference. A cover member 16 is coupled to the end face on the other side. The cover member 16 has a straight cylindrical portion 17 and a spherical portion 18 smoothly connected to the cylindrical portion 17, and is press-molded from a steel plate material. The end of the cylindrical portion 17 is welded to the nut body 13 . As shown in FIG. 2A, the diameter of the nut body 13 is slightly larger than the diameter of the cover member 16, so that the boundary between the nut body 13 and the cover member 16, that is, the end face of the nut body 13 A narrow annular pressurized surface 19 is formed on the . The nut body 13 is generally hexagonal, but may be square or octagonal.

The inner diameter of the receiving hole 12 of the pressure member 9 is slightly larger than the diameter of the cylindrical portion 17 of the cover member 16 . By doing so, when the cover member 16 is inserted into the receiving hole 12, the diametrical movement of the cap nut 20 is substantially zero, and only sliding in the direction of the central axis OO is permitted.

Next, the stopper member will be explained.

The stopper member 21 is composed of a large-diameter portion 23 in which the permanent magnet 22 is accommodated, and a small-diameter portion 24 for attracting the cap nut 20 by the attraction force of the permanent magnet 22 . The large-diameter portion 23 has a vessel-like shape with a circular cross section, and the permanent magnet 22 is fitted therein. The small diameter portion 24 is shaped like a bar with a circular cross section and is welded to the large diameter portion 23 . The blackened portion is the welded portion 26 . The large diameter portion 23 is slidably inserted into the large diameter hole 6 of the guide cylinder 8 , and the small diameter portion 24 is slidably inserted into the small diameter hole 7 of the guide cylinder 8 . Large diameter portion 23 is made of a non-magnetic material such as stainless steel. Also, the small diameter portion 24 is made of a magnetic material such as soft iron.

The small-diameter portion 24 extends into the receiving hole 12 , and the length of the small-diameter portion 24 is set so that the stopper surface 27 formed on the distal end surface of the small-diameter portion 24 is positioned within the receiving hole 12 . Also, the diameter of the small diameter portion 24 is set smaller than the inner diameter of the receiving hole 12, thereby forming a gap 28. As shown in FIG.

A cup-shaped heat insulating/insulating material 31 is inserted inside the base member 3 , and a compression coil spring 32 is arranged between the heat insulating/insulating material 31 and the stopper member 21 . The tension of the compression coil spring 32 presses the end surface 33 of the large diameter portion 23 of the stopper member 21 against the inner end surface 34 of the large diameter hole 6 of the guide cylinder 8 . By this pressing, the standby position of the stopper surface 27 is set. The heat insulating/insulating material 31 is made of a synthetic resin material such as polytetrafluoroethylene (trade name: Teflon, registered trademark).

A fixed electrode 29 is arranged coaxially with the electrode main body 1, and a steel plate component 30 is placed thereon.

As a method for inserting the cover member 16 into the receiving hole 12, an operator manually inserts the cover member 16 into the receiving hole 12, or inserts it with a supply rod operated by a driving means.

Next, the operation will be explained.

When the cover member 16 is inserted into the receiving hole 12 of the pressure member 9, the attractive force of the permanent magnet 22 acts on the cover member 16 through the small diameter portion 24, and the cover member 16 is drawn into the receiving hole 12, thereby closing the cover. A tip portion (spherical portion 18 ) of the member 16 is attracted to the stopper surface 27 . At this stage, a slight gap L is formed between the pressing surface 11 of the pressing member 9 and the pressed surface 19 of the nut body 13 . Then, when the electrode body 1 advances while the cover member 16 is held by the stopper surface 27 , the welding projection 15 of the nut body 13 is pressed against the steel plate component 30 . As the pressing progresses further, this pressing reaction force acts, compressing the compression coil spring 32 and pushing the stopper member 21 relatively, so that the pressing surface 11 of the pressing member 9 contacts the pressed surface 19 of the nut body 13 . It fits snugly over the entire area. A welding current is applied in this state, and welding to the steel plate component 30 is completed.

The effects of the embodiment described above are as follows.

The cylindrical portion 17 of the cover member 16 is a cylindrical member having a straight cylindrical surface and a smooth surface. It is possible to greatly reduce the gap between the portion 17 and the outer surface, and minimize the amount of deviation of the cap nut 20 from the center axis OO of the electrode. In other words, the gap between the inner surface of the receiving hole 12 and the outer surface of the cylindrical portion 17 is substantially zero, and the cover member 16 can be inserted into and pulled out of the receiving hole 12, that is, the degree of insertion of the cover member 16 in a so-called sliding state. can be truncated. Accordingly, the cap nut 20 is held coaxially with respect to the center axis OO of the electrode, the relative positions of the nut body 13 and the pressure surface 11 of the pressure member 9 are accurately set, and the pressure surface 11 contact over the entire peripheral area of the pressurized surface 19 of the nut body 13, the pressurizing force of the pressurizing surface 11 against the pressurized surface 19 acts on the nut body 13 without being biased, and the welded state of each welding projection 15 is Welding quality is improved by uniformly good welding over the entire area.

As a feature of the shape of the cap nut 20, since the nut body 13 and the cover member 16 are integrated, the length in the axial direction is significantly longer than that of a normal projection nut. That is, they are taller. Therefore, if some lateral external force acts on the front end of the cover member 16 after welding, the welded portion may be peeled off or damaged, increasing the inclination of the cap nut 20 as a whole. Such an inclination is due to the fact that the pressure surface 11 of the pressure member 9 is not uniformly in contact with and pressurized against the pressure-receiving surface 19 of the nut body 13 over the entire circumference. This is due to the variation in . In order to avoid such a problem, it is essential that the pressurizing surface 11 of the pressurizing member 9 uniformly contacts and pressurizes the pressurized surface 19 of the nut body 13 over the entire circumference. With such a normal contact state, the cap nut 20 is maintained coaxially or substantially coaxially with the center axis OO of the electrode. The welding projections 15 are in contact with the pressure surface 19 over the entire area, and each welding projection 15 applies a uniform pressure load to the steel plate component 30 . Therefore, even if the cap nut 20 is tall, it is possible to secure strong welding to the steel plate component 30 without tilting.

Since the length of the small diameter portion 24 is set so that the stopper surface 27 of the small diameter portion 24 is positioned within the receiving hole 12 , the cover member 16 is inserted into the receiving hole 12 and remains surrounded by the receiving hole 12 . In this state, the suction of the cover member 16 is stopped by the stopper surface 27 standing by in the middle of the receiving hole 12 in the longitudinal direction. In this manner, a suction force acts on the cover member 16 within the receiving hole 12, and the cylindrical portion 17 of the cover member 16 is inserted into the receiving hole 12 with substantially no gap. Therefore, even if some external force acts on the lower portion of the cap nut 20 in the diametrical direction, the rocking displacement of the cap nut 20 with respect to the central axis OO of the electrode can be reduced to a level that causes no actual damage. This ensures proper welding.

Since the length of the small-diameter portion 24 is set so that the stopper surface 27 formed on the tip surface of the small-diameter portion 24 is positioned within the receiving hole 12, the length of the small-diameter portion 24 can be made as long as possible. , the amount of heat transferred from the small-diameter portion 24 to the permanent magnet 22 can be reduced, and the durability of the permanent magnet 22 can be improved.

In the cap nut 20 in which the cover member 16 is integrated with the nut body 13, the pressurized surface 19 formed on the end face of the nut body 13 on the cover member 16 side has a narrower width in the diametrical direction. In this embodiment, since the cylindrical portion 17 is inserted into the receiving hole 12 with substantially no gap, the cover member 16 is coaxial or substantially coaxial with the center axis OO of the electrode. Positional accuracy can be ensured. Therefore, even if the width of the pressurized surface 19 is narrow, the pressurizing surface 11 of the pressurizing member 9 can be brought into close contact with the entire peripheral area of the pressurized surface 19 , and the welding projections 15 can be uniformly applied to the steel plate component 30 . pressure and good weld quality.

The mass of the nut body 13 is larger than the mass of the cover member 16, and the nut body 13 is exposed from the pressure surface 11, but the cylindrical portion 17 of the cover member 16 is tightly inserted into the receiving hole 12. Therefore, the displacement of the cap nut 20 in the swinging direction due to the mass can be minimized.

The small-diameter portion 24 extending into the receiving hole 12 has an outer diameter smaller than the inner diameter of the receiving hole 12 , and a gap 28 is left between the small-diameter portion 24 and the receiving hole 12 . Since such an air gap 28 is left, the attractive force of the permanent magnet 22 acts only on the cover member 16 from the small diameter portion 24, and the attractive force on the cap nut 20 can be strongly applied.

FIG. 3 shows Example 2 of the present invention.

In the cap nut 20 of the second embodiment, a flange 35 is formed integrally with the nut body 13, and the welding projection 15 is provided on the flange 35. As shown in FIG. By increasing the length of the receiving hole 12 , both the cylindrical portion 17 of the cover member 16 and the nut body 13 can be inserted into the receiving hole 12 . The length of the small-diameter portion 24 is set so that the stopper surface 27 formed on the distal end surface of the small-diameter portion 24 along with the extension of the receiving hole 12 is positioned near the open end 37 of the small-diameter hole 7 .

The gap between the inner surface of the receiving hole 12 and the corner of the nut body 13 is substantially zero, and the fitting degree of the nut body 13 is reduced in a so-called sliding state in which the nut body 13 can be inserted into or pulled out of the receiving hole 12. There is. Therefore, it is the same as that in which the cover member 16 in the first embodiment is inserted into the receiving hole 12 in a slidable state. In FIG. 3, the gap between the corner of the nut body 13 and the inner surface of the receiving hole 12 is exaggerated.

The vicinity of the opening end 37 of the small-diameter hole 7 means that the end surface of the small-diameter portion of the guide cylinder 8 and the stopper surface 27 are on the same imaginary plane, or the end surface of the small-diameter portion of the guide cylinder 8 and the stopper surface 27 is meant to slightly protrude toward the cap nut 20 side. The rest of the configuration is the same as that of the first embodiment, including parts not shown, and members having similar functions are denoted by the same reference numerals.

Since the cylindrical portion 17 of the cover member 16 and the nut body 13 are inserted into the receiving hole 12, the cap nut 20 as a whole is held in the receiving hole 12, and the holding stability of the cap nut 20 is improved. Since the length of the small-diameter portion 24 is set so that the stopper surface 27 formed on the tip surface of the small-diameter portion 24 is positioned in the vicinity of the opening end 37 of the small-diameter hole 7, the length of the small-diameter portion 24 can be shortened. As a result, the attractive force of the permanent magnet 22 can be made to act on the cap nut 20 more strongly, and the holding stability of the cap nut 20 is improved. Other effects are the same as those of the first embodiment.

As described above, according to the electrode of the present invention, the unique shape of the cap nut is used to stably hold the nut in the receiving hole of the electrode. 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.

Reference Signs List 1 electrode body 6 large-diameter hole 7 small-diameter hole 8 guide tube 9 pressure member 11 pressure surface 12 receiving hole 13 nut body 15 welding projection 16 cover member 17 cylindrical portion 19 pressurized surface 20 cap nut 21 stopper member 22 permanent magnet 23 Large-diameter portion 24 Small-diameter portion 27 Stopper surface 28 Gap 30 Steel plate component 37 Opening end L Gap

Claims (1)

A cap nut in which a welding projection is provided on one end face of a nut body and a cover member having a cylindrical portion is integrated on the other end face, and is intended to be welded to a steel plate part,
A narrow annular pressurized surface is formed at the boundary between the nut body and the cover member,
The cylindrical portion has a cylindrical surface with a straight and smooth surface,
An electrode body having a circular cross section and a cylindrical shape is configured using a metal material,
A pressurizing member coupled to the end of the electrode body is formed with a pressurizing surface that is in close contact with the surface to be pressurized, and is formed with a receiving hole into which the cylindrical portion of the cover member is inserted. and the outer surface of the cylindrical portion is substantially zero, and the cylindrical portion slides against the receiving hole,
A guide cylinder made of an insulating material and formed with a large diameter hole and a small diameter hole is inserted into the electrode main body,
The stopper member is composed of a large-diameter portion in which the permanent magnet is accommodated and a small-diameter portion for attracting the cap nut by the attraction force of the permanent magnet,
The large-diameter portion of the stopper member is slidably inserted into the large-diameter hole of the guide cylinder, and the small-diameter portion of the stopper member is slidably inserted into the small-diameter hole of the guide cylinder. ,
A gap is formed between the small-diameter portion and the receiving hole by making the diameter of the small-diameter portion smaller than the inner diameter of the receiving hole,
The length of the small diameter portion is set so that the stopper surface formed on the tip end surface of the small diameter portion is positioned in the middle of the receiving hole and receives the cover member . Electric resistance welding electrodes.

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