JP2021178355A - Projection forming method - Google Patents

Abstract

To provide a projection forming method capable of forming a projection of sufficient size at a low cost and without impairing the appearance even when a metal plate having a thick thickness is used.SOLUTION: Two plane-shaped metal members 30, 31 are superimposed, subsequently, the superimposed two metal members 30, 31 are mounted on a table electrode of a resistance welding machine, in such a state, the setting of welding conditions with respect to metal members 30, 31 (quality of material, plate thickness, electric current value, electric conduction time and pressuring force) is performed and a cap tip 25 set up on a tip portion of a welding gun is applied onto a spot on which the formation of a projection is desired, on an upper surface of the metal member 30 after the setting of the welding conditions. In such a state, electricity is conducted while pressurizing is performed (process (b)) and a nugget 32 is formed on a joint portion between the two metal members 30, 31 (process (c)). After forming the nugget 32, the metal members 30, 31 are stripped (process (d)).SELECTED DRAWING: Figure 1

Description

The present invention relates to a projection forming method for forming a projection on a metal member for resistance welding.

In the resistance welder, two rod-shaped electrodes are opposed to each other, one (lower side) is fixed, and the other (upper side) can be moved up and down, which is called a stationary type, or one of the two electrodes (lower side). There is a so-called table type in which the side) is fixed as a table shape (plate shape) and the other (upper side) is a gun shape that can be moved up, down, left and right. In both methods, the object to be welded is sandwiched between two electrodes, and welding is performed by energizing while pressurizing with the upper electrode. In resistance welding, projections are formed on one of the two metal members to be joined in order to enable good welding. By forming the projection, it becomes possible to pass the current in a concentrated manner, and good welding becomes possible. The two metal members to be joined may both have a flat plate shape, or one may have a flat plate shape and the other may have a nut or stud, but in the present specification, both have a flat plate shape. do.

As a method for forming a projection, in addition to a method of embossing with a press machine, there are, for example, the methods described in Patent Document 1 and Patent Document 2. The method of embossing with a press machine is a method of embossing on one surface side of a metal member for which a projection is to be formed by applying a die to one surface side and pressurizing the metal member. In the projection forming method described in Patent Document 1, the tip of a cone punch having a sharply formed tip is pushed from the work surface to a predetermined depth to form a depressed portion on the work surface, and the meat is raised on the peripheral edge of the depressed portion. This is a method of forming a projection on the work surface. The projection forming method described in Patent Document 2 is a method of irradiating a predetermined position of a welded material with a laser beam to melt the surface of the welded material, cooling the surface, and forming protrusions by the surface tension effect of the molten portion.

Japanese Unexamined Patent Publication No. 06-405490 Japanese Unexamined Patent Publication No. 57-091887

However, in the method of forming a projection by embossing with a press machine, in the case of a thick metal plate, a press machine having a large pressing force is required, and the equipment becomes expensive. Further, as shown in FIG. 3, in the thick metal plate 50, the projection 51 can be formed only a little, and the portion 52 to which the mold is applied is greatly dented and the appearance is spoiled. The thick metal plate is, for example, a metal plate having a thickness of 3.0 mm or more.

In the projection forming method described in Patent Document 1 described above, since the projection is formed by hitting a cone punch on the metal plate and raising the meat on the peripheral edge of the depressed portion, the projection of a large protrusion is formed. Not suitable for.

The projection forming method described in Patent Document 2 requires laser equipment, which is expensive.

The present invention has been made in view of the above circumstances, and provides a projection forming method capable of forming a projection having a sufficiently large size even with a thick metal plate at low cost and without spoiling the aesthetic appearance. With the goal.

The projection forming method of the present invention includes a step of superimposing two flat metal members and then spot welding the two metal members to a desired projection forming portion, and the two metals in a bonded state by the step. It includes a process of peeling off a member.

According to the above method, two metal members are joined at a spot weld by spot welding two overlapped metal members, and two metal members in a joined state are peeled off to form a spot weld. The formed nugget remains as a projection, and the metal member with the remaining nugget can be used as a metal member with projection.

In this way, by using the nugget formed between the two metal members by spot welding as a projection, it is possible to obtain a sufficiently large projection even on a thick metal plate. The size of the nugget formed between the two metal members is determined by adjusting the current flowing between the two metal members, the time for the current to flow (energization time), and the pressing force to pressurize between the two metal members. Can be changed. That is, by adjusting the current value, the energization time, and the pressing force, it is possible to form a projection of an arbitrary size.

Moreover, since the projection can be formed only by the existing resistance welder, no dedicated equipment for forming the projection is required. That is, there is no equipment cost for forming the projection. Further, in the method of launching the projection by a press machine, a mark may be left on the side to which the die is applied and the aesthetic appearance may be spoiled, but this is not the case in the present invention.

In the projection forming method, the two metal members are both made of the same material.

According to the above method, it is possible to form a projection of a material common to the two metal members.

In the projection forming method, the two metal members are made of different materials.

According to the above method, it is possible to form a projection in which two metal members are mixed.

According to the present invention, it is possible to form a projection having a sufficient size even with a thick metal member, and since no special equipment other than a resistance welder is required, the equipment cost can be saved. Further, since no trace is left on the metal member, the appearance is not spoiled.

The figure which shows the projection formation process for demonstrating the projection formation method of this invention. The figure which shows the result of having formed the projection by the projection forming method of this invention with two metal members of thin plates each other. Figure to explain the problem of the method of forming a projection by launching with a press machine Side view showing the appearance of a table-type resistance welder

Hereinafter, preferred embodiments for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 4 is a side view showing the appearance of the table-type resistance welder 1. In the figure, the resistance welder 1 includes a cooling unit 10, a power supply unit 11, a support post 12, a support arm 13, a welding gun 14, conductive cables 15A and 15B, a table electrode 16, and a gantry 17. The operation panel 18 and the welding transformer 19 are provided.

The cooling unit 10 supplies cooling water for cooling the welding gun 14, the conductive cables 15A and 15B, the support arm 13, the table electrode 16, the welding transformer 19, and other parts through which an electric current flows. The cooling unit 10 always operates while the power is turned on to the resistance welder 1 to circulate the cooling water with the welding gun 14. The power supply unit 11 starts its operation by being activated by the operation panel 18. The power supply unit 11 rectifies three-phase AC power supplied from a power receiving facility (not shown) and converts it into direct current, and outputs high-frequency alternating current controlled by PWM (Pulse Width Modulation) from the obtained direct current.

The high-frequency alternating current output from the power supply unit 11 is supplied to the welding transformer 19 built in the front side of the gantry 17. The support post 12 is erected vertically in the vicinity of the cooling unit 10 and the power supply unit 11 to rotatably support the support arm 13 in the horizontal direction. The support arm 13 has a substantially L-shape including a horizontal arm portion 13A extending horizontally with respect to the support post 12 and a vertical arm portion 13B extending vertically downward from the tip portion of the horizontal arm portion 13A. , Holds the welding gun 14 at the tip portion.

The welding gun 14 is swingably held by the tip portion of the vertical arm portion 13B of the support arm 13 so as to draw an arc in the vertical direction. A spring coil 13C is stretched between the base end portion of the welding gun 14 and the tip end portion of the vertical arm portion 13B, and the contraction force of the spring coil 13C causes the base end portion side of the welding gun 14 to be on the upper side in the vertical direction. Is lifted to. Further, the tip portion of the welding gun 14 is pressurized in the direction toward the table electrode 16 by the cylinder 26 provided at the base end portion of the vertical arm portion 13B.

A chain (not shown) is built in the vertical arm portion 13B, one end of the chain is connected to a cylinder, and the other end is connected to a power point portion (not shown) of the welding gun 14. By operating the cylinder 26 in the direction of pulling up the chain, the welding gun 14 rotates, and the tip portion thereof is in pressure contact with the table electrode 16. The pressure welding of the welding gun 14 to the table electrode 16 is performed immediately before the start of welding (that is, immediately before the welding current is supplied), and is released after the welding is completed. The mechanism for injecting air into the cylinder 26 will not be described. A removable cap tip 25 is attached to the tip of the welding gun 14.

One end of the conductive cable 15A is connected to a positive electrode (not shown) at the secondary output end of the welding transformer 19, and the other end is connected to the welding gun 14. One end of the conductive cable 15B is connected to a negative electrode (not shown) at the secondary output end of the welding transformer 19, and the other end is connected to the table electrode 16. For the conductive cables 15A and 15B, a metal material having excellent conductivity and thermal conductivity such as copper is used. An object to be welded is placed on the table electrode 16. As described above, the object to be welded is a plate set composed of two metal plates such as steel plates. The gantry 17 has a table drive mechanism that moves the table electrode 16 up and down in the vertical direction.

Returning to FIG. 1, the operation panel 18 has a display such as a liquid crystal panel (not shown) and a touch panel (not shown) such as a resistance film type mounted on the display surface of the display. Welding conditions (“material”, “plate thickness”, “current value”, “energization time”, “pressurization”) for the object to be welded are set through the touch panel of the operation panel 18. The welding transformer 19 is a welding transformer for resistance welding previously proposed by the inventors of the present application in Japanese Patent Application Laid-Open No. 2012-210654 (Patent No. 5491560) and Japanese Patent Application Laid-Open No. 2013-179205 (Patent No. 5220931). It has the feature of being able to supply a large current in time.

The resistance welder 1 is configured as described above.
Next, a method of forming a projection on a metal member using the resistance welder 1 will be described. FIG. 1 is a diagram showing a projection forming process by the projection forming method of the present invention. Here, the two metal members 30 and 31 are made of the same material (for example, SPCC (Steel Plate Cold Commercial), SECC (electrozinc plated SPCC), SGCC (hot dip galvanized SPCC) or SUS (Steel). SpcialUse Stainless))).

In the figure, first, two flat plate-shaped metal members 30 and 31 are superposed (step (a)). Next, the two superposed metal members 30, 31 are placed on the table electrode 16 of the resistance welder 1. Then, on the operation panel 18, welding conditions (“material”, “plate thickness”, “current value”, “energization time”, “pressurization”) for the metal members 30 and 31 are set, and then the metal member The cap tip 25 attached to the tip portion of the welding gun 14 is applied to a portion of the upper surface of the 30 where the projection is desired to be formed. In that state, energization is performed while pressurizing (step (b)).

By pressurizing and energizing, the nugget 32 is formed at the joint between the two metal members 30 and 31 (step (c)). At this time, if the metal members 30 and 31 have the same plate thickness, the nugget 32 is formed between the metal members 30 and 31. After the metal members 30 and 31 are joined, they are peeled off (step (d)). In this case, one of the metal members (for example, the metal member 30) can be peeled off in a clean state by twisting in a direction perpendicular to the thickness direction thereof. By peeling off one metal member, the nugget 32 remains on the other metal member, and projection can be obtained.

As described above, according to the projection forming method of the present invention, the nugget formed between the two metal members 30, 31 by spot welding the two overlapping metal members 30, 31 is used as the projection. Therefore, it is possible to obtain a sufficiently large projection even with a thick metal plate. The size of the nugget can be changed by adjusting the current flowing between the two metal members, the energization time, and the pressing force. Further, since the projection can be formed only by the existing resistance welder 1, no dedicated equipment for forming the projection is required. That is, there is no equipment cost. In addition, it does not spoil the aesthetics of the method of launching a projection with a press machine.

Although the present invention has been described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
For example, the metal members 30 and 31 may be made of the same material or may be made of different materials. If both are made of the same material, the nugget formed will be a mixture of these materials. If the materials are different from each other, the nugget is formed on the thinner side of the plate, so that the size and shape of the projection will be different from those of the same plate thickness.

On the other hand, when the metal members 30 and 31 are both thin plates, as shown in FIG. 2, a hole 35 may be formed on the side where the nugget does not remain (for example, the metal member 30).

In the above embodiment, a table type welder is used for forming the projection, but a stationary type welder can also be used, of course.

The present invention is suitable for applications that form projections on metal members for resistance welding.

1 Resistance welder 10 Cooling unit 11 Power supply unit 12 Support post 13 Support arm 14 Welding gun 15A, 15B Conductive cable 16 Table electrode 17 Stand 18 Operation panel 19 Welding transformer 25 Cap tip 26 Cylinder 30, 31 Metal member 32 Nugget 32A Recess 32B Projection 35 holes

Claims (3)

After superimposing two flat metal members, spot welding is performed on the desired projection formation points of the two metal members.
A step of peeling off the two metal members in a joined state by the above step, and a step of peeling off the two metal members.
To prepare
Projection formation method. The two metal members are both made of the same material.
The projection forming method according to claim 1. The two metal members are made of different materials.
The projection forming method according to claim 1.

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