JPH0347751Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a device for preventing reverse welding of a nut or the like when welding a nut or the like to a base material in the industry of manufacturing parts for industrial machinery.

(Prior Art) Conventionally, as a device used for welding work in the parts manufacturing industry of industrial machinery, such as the automobile industry, two materials to be welded are pressurized by opposing electrode tips, and a large current is applied. So-called resistance welding, which joins materials by utilizing resistance heat generated by short-time energization, is commonly used because of its rapid welding speed and excellent productivity.

The industry requires that these two members be joined in the correct position and orientation.

As a device developed in view of these demands, there is known a reverse welding prevention device such as a nut as shown in FIGS. 12 and 13, for example.

This thing has a plurality of welding protrusions b protruding outward from the nut body a on one side of the nut to be welded 12.
An iron ring 13 that contacts only the protrusion b is attached to the outside of the end of the copper electrode tip 14.

Therefore, when the nut 12 is placed normally as shown in FIG. 13, and in this state, if the two members 12 and 15 are energized while being pressurized by the pair of electrode chips 14, the protrusion b of the nut 12 will be welded to the base material 15. , the nut 12 is reliably welded to the base material 15.

Further, as shown in FIG. 13, when the nut 12 is placed with its front and back reversed, the protrusion b protruding outward from the nut body a comes into contact with the ring 13, and at the same time, the other side faces toward the base material 15. Something that comes into contact with
In this state, when pressure is applied by the pair of electrode chips 14 and electricity is applied to these two members 12 and 15,
Since the contact area of the protrusion b of the nut 12 is smaller than that of the other side, this part receives resistance heat first than other parts and starts melting, and at the same time a predetermined pressure is applied, welding to the ring 13. On the other hand, the other side surface with a large contact area does not melt with the base material 15 during the predetermined energization time and is not fused. Therefore, reverse welding of the nut 12 to the base material 15 is not possible. Completely prevented.

(Problem to be solved by the invention) However, as shown in FIGS. 3 to 8, the above-mentioned conventional reverse welding prevention devices such as nuts, etc.
When using a nut 12 in which the protrusion b does not protrude to the outside of the main body a, if the nut 12 is placed in the opposite direction, the protrusion b will come into contact with the electrode tip 14 but not the ring 13 on the outer periphery. In addition, since the other side surface contacts the base material 15, the nut 12 generates resistance heat at the contact surface between the other side surface and the base material 15 and is welded. However, since the contact area of the nut 12 is large, When the current is applied within the time, the two members 12,
15 cannot be melted to provide sufficient bonding force, and when using this welded product, there is a problem that the nut 12 may be missing due to insufficient strength, resulting in defective products. It was hot.

The present invention was made to solve the above-mentioned problems, and the other side of the nut corresponds to the base material. In other words, when the nut is set in the opposite direction, a positioning guide is provided that protrudes from one side of the nut. When the tip comes into contact with the core metal provided on the end surface of the electrode tip, welding occurs in this area and is not welded to the base material, so it is possible to uniformly and completely reverse weld nuts, etc., regardless of the shape of the nut or the state of the protrusion formation. The purpose is to provide a device that can prevent this.

(Means for Solving the Problems) The means of the present invention for achieving the above-mentioned object comprises: a base material having a guide hole bored in the center of the surface to be welded; a positioning guide located on the outer periphery of the screw hole and inside the main body, protruding concentrically with the screw hole, and having a side edge engaged with the guide hole of the base material; A nut having a welding protrusion that protrudes lower than the positioning guide and has a smaller surface area than the non-welded surface on the other side, and a pair of upper and lower electrodes that are arranged opposite to each other so as to be able to advance and retreat with the nut and base material in between. When the non-welded surface of the nut is placed opposite to the welding surface of the base material by inserting it into the mounting hole of the pressing surface of the chip and the electrode chip placed opposite to the nut side,
A reverse welding prevention device, such as a nut, includes a core metal that is in contact with the protruding surface of the positioning guide.

(Function) With the above-mentioned configuration, the device for preventing reverse welding such as a nut of the present invention exhibits the following functions.

The apparatus of the present invention uses a so-called resistance welding method in which two materials to be welded are pressurized by opposing electrode tips and joined by utilizing resistance heat generated by short-time application of a large current.

As shown in Figures 1 and 2, when welding with the nut to be welded placed on the lower electrode tip side and the base material placed on the upper electrode tip side, the nut is placed on the positioning guide as shown in Figure 1. Normally, when the nut is placed on the lower electrode chip with one side with the welding protrusion facing up, place the base material on top of this nut and press it with the upper electrode chip, and the nut will fit into the guide hole of the base material. The positioning guide is inserted and positioned, and the welding protrusion comes into contact with the bottom surface of the base material. In this state, when the upper and lower electrode chips apply a certain amount of pressure and energize, the electrode chips have better conductivity. The nut and base material, which are inferior in quality, generate resistance heat at the contact surface, and first, the protrusion with a small contact area melts, and a part of the base material also melts and fuses, resulting in a strong welding of the two members. Ru.

However, as shown in Figure 2, if the nut is placed on the lower electrode chip with the positioning guide and protrusion facing down, a base material is placed on top of this, and the upper electrode chip is pressed down, the positioning of one side of the nut can be adjusted. The end of the guide is in contact with the core metal provided on the end face of the lower electrode chip, and the other side of this nut is in contact with the base material, and in this state, when pressure and electricity are applied by the electrode chip, Since the positioning guide on one side of the nut has a smaller contact area than the other side, large resistance heat generation occurs at the contact area between the positioning guide and the core metal, while the contact area between the other side and the base material generates large resistance heat. does not generate resistance heat that leads to melting, so the positioning guide and the core metal are melted and fused and welded, and the other side and the base material are not welded, so-called.
Reverse welding of the nut to the base material is prevented.

At this time, since the positioning guide is formed inside the nut body and inside the protrusion, it can be used even with a nut in which the protrusion does not extend beyond the main body.

(Embodiment) Next, an embodiment of the reverse welding prevention device for nuts and the like related to the present invention will be described based on the drawings.

The nut 1 used for welding with the base material 9 in this embodiment device has a main body a formed in a hexagonal, circular, square, etc. shape as shown in FIGS. A screw hole 8 is passed through the center of a, and one side is a welding surface and the other side is a non-welding surface. One side of the nut 1 on the side to be welded is located on the outer periphery of the screw hole 8, protrudes concentrically with the screw hole 8, and has a side edge that is connected to the guide hole 10 of the base material 9. It has a positioning guide c that engages with the positioning guide c, and is provided on the outer periphery of the positioning guide c and protrudes at a lower height than the positioning guide c,
It has a smaller surface area than the non-welded surface on the other side, and is formed to have three or more welding protrusions b so as not to protrude from the main body a.

A pair of upper and lower copper electrode chips 2 and 3 are arranged opposite each other so as to be able to move forward and backward so as to sandwich the nut 1 and the base material 9, and the first embodiment shown in FIGS. In the case of this example, the upper electrode chip 2 is formed with a flat end face, and the lower electrode chip 3 has a guide recess 4 in which a part of the nut 1 is accommodated.
As shown in FIGS. 1 and 2, the ring 6 may be formed integrally with the chip body, or a separate ring 6 may be fitted on the outer periphery of the chip body or on the stepped portion 5 as shown in FIGS. 9 and 10. It is formed by

Then, a core bar 7 made of the same quality as the nut 1, for example, made of iron, is removably inserted into the mounting hole s provided in the guide recess 4 on the pressing surface of the electrode chip 3 placed opposite to the nut 1 side. It is fitted into the guide recess 4 and is formed to have the same size as the positioning guide c, and is lowered slightly below the bottom of the guide recess 4 as shown in Figures 1 and 2, or as shown in Figure 10. The nut 1 is aligned with the bottom as shown in the figure, or has a recess d around the screw hole 8 as shown in FIG.
In this case, a nut having a diameter smaller than that of the recess d is buried above the bottom part, and when the non-welded surface of the nut 1 is opposed to the surface to be welded of the base material 9, i.e. , when the nut 1 is placed in the opposite direction, the protruding surface of the positioning guide c comes into contact with the core metal 7.

In addition, in the case of the second embodiment shown in FIG. 11, the configuration of the chips 2 and 3 is formed opposite to that of the first embodiment described above, so that the end surface of the lower electrode chip 3 is flat. and a positioning pin 1 that fits into the screw hole 8 of the nut 1 in the center thereof.
1 is provided, and the end face of the upper electrode chip 2 is also formed as a flat end face without a guide recess 4, and a core bar 7 that contacts only the positioning guide c of the nut 1 is buried in the center thereof.

When the positioning guide c of the nut 1 is welded to the core bar 7, the entire chip in which the core bar 7 is buried can be replaced, or only the core bar 7 can be removed from the mounting hole s and replaced. Welding work resumes.

The effects of the first and second embodiments described above are as described in the effect section above, so detailed explanations will be omitted.

(Effect of the invention) The device for preventing reverse welding of a nut, etc. of the present invention, configured as described above, has a positioning guide formed inside the nut body and further inside the welding protrusion. The set nut always makes contact with the core metal provided in the center of the chip,
By welding the positioning guide of the nut to the nut, reverse welding is completely prevented even if the protrusion formed for welding does not protrude outside the main body of the nut.
This has a special effect of completely eliminating the occurrence of defective products.

[Brief explanation of the drawing]

Figures 1 and 2 are longitudinal sectional front views showing the first embodiment of the nut reverse welding prevention device according to the present invention. Figure 1 shows the nut placed normally, and Figure 2 shows the nut placed reversely. Indicates the case where FIG. 3 is a plan view of the hexagonal nut in the same as above. Figure 4 is a front view of the same as above. Figure 5 is a plan view of the circular nut. Figure 6 is a bottom view of the same as above. Figure 7 is a plan view of the square nut. Figure 8 is a bottom view of the same as above. FIGS. 9 and 10 are partial longitudinal sectional front views showing other examples of the lower electrode chip. 11th
The figure is a longitudinal sectional front view showing the second embodiment. FIGS. 12 and 13 show a conventional device for preventing reverse welding of nuts, etc. FIG. 12 shows the case where the nut is placed normally, and FIG. 13 shows the case where the nut is placed in reverse.
FIG. 14 is a plan view of the nut in the same as above. 15th
The figure is a bottom view of the same as above. In the figure, 1 is a nut, b is a welding protrusion,
c is a positioning guide, 2 and 3 are electrode tips, 7
is a core metal, 8 is a screw hole, 9 is a base material, 10 is a guide hole, and s is a mounting hole.

Claims (1)

[Scope of utility model registration request] A base material with a guide hole drilled in the center of the surface to be welded, and a guide hole located on one side of the surface to be welded, located on the outer periphery of the screw hole and inside the main body, and protruding concentrically with the screw hole. Welding that has a positioning guide whose side edge engages with the guide hole of the base material, is located on the outer periphery of the positioning guide and protrudes lower than the positioning guide, and has a smaller surface area than the non-welded surface on the other side. a nut having a projection, a pair of upper and lower electrode chips that are arranged opposite to each other so as to be freely advanced and retracted with the nut and a base material in between, and the electrode chips that are arranged opposite to each other on the nut side and are inserted into mounting holes on the pressing surface of the electrode chips. and a core metal with which the protruding surface of the positioning guide comes into contact when the non-welded surface of the nut is placed opposite to the surface to be welded of the base material. Device.