JPH0847782A - Seam welding method and apparatus - Google Patents

Abstract

(57) [Summary] [Purpose] Welding work of anti-corrosion plated steel sheets is facilitated and
Provided are a seam welding method and apparatus that do not generate blowholes. A contact peripheral surface 21 of an electrode roller 20 that contacts the objects to be welded 4 and 5 is formed by a contact peripheral surface 21 having a shape in which a center portion in the width direction bulges outward in the radial direction. 2 superposed
One piece of the objects to be welded 4, 5 is connected to the pair of electrode rollers 20, 2
It is pressed with 0 to sandwich it, and the electrode rollers 20 and 20 energize the objects to be welded 4 and 5. Shaping tool 25 having a shaping portion 26 recessed in a shape matching the contact peripheral surface 21 of the electrode roller 20.
The shaping tool 26 is provided with an elastic force by the pressing means 30 to press the shaping section 26 against the contact peripheral surface 21.
The receiving tooth portion 23 is formed on the outer peripheral surface of the electrode roller 20 along at least one side of the contact peripheral surface 21. The knurl drive wheel 32 has a transmission tooth portion 34 that meshes with the receiving tooth portion 23.
And an escape groove portion 33 forming a space between the contact peripheral surface 21 of the electrode roller 20 and the contact peripheral surface 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seam welding method and apparatus used, for example, for welding a flange portion of a fuel tank of an engine.

[0002]

2. Description of the Related Art As shown in FIG. 7, a conventional fuel tank 1 for an engine is manufactured by overlapping and welding flange portions 4 and 5 of a lower half portion 2 and an upper half portion 3, respectively. The contact surfaces of the flange portions 4 and 5 thus overlapped are generally liquid-tightly joined by seam welding (see Japanese Patent Publication No. 57-37434). The seam welding device 6 sandwiches both flange portions 4 and 5 with a pair of electrode rollers 7 and 8, and
Both flange parts 4, 5 via the bearing part (not shown) of this.
Then, the flange portions 4 and 5 are energized through the electrode rollers 7 and 8.

Since the contact portions of the flange portions 4 and 5 have a large electric resistance, they generate heat to be in a semi-molten state and are welded to each other by the pressure applied from the upper electrode roller 7. Further, in the knurl drive type seam welding device, the transmission tooth portions 13 and 14 of the knurl drive wheels 11 and 12 are meshed with the receiving tooth portions 9 and 10 formed on the peripheral surfaces of the electrode rollers 7 and 8, respectively. 7, 8 are rotated along the flange portions 4, 5 by receiving the rotational force of the knurled drive wheels 11, 12.

[0004]

By the way, in recent years, the fuel tank 1 has been manufactured mainly by using a rust-preventive plated steel plate coated with zinc on both sides in order to obtain a high rust-proof property that can withstand gasoline. There is. However, when the rust-preventive plated steel sheet is seam-welded, the following problems occur due to the influence of the plated zinc.

That is, since zinc has a relatively low melting point of 420 ° C., it is melted before the objects to be welded such as the flange portions 4 and 5 of the fuel tank 1 and the objects to be welded to the electrode rollers 7 and 8 are melted. Adheres to the peripheral surface. Therefore, the contact resistance between the electrode rollers 7 and 8 increases, the current flowing through the object to be welded decreases, and the object to be welded may be insufficiently melted to make the welding operation difficult. Further, when the molten zinc enters the molten portion of the welded object, the boiling point of zinc is relatively low, so that it is evaporated and blow holes are generated. Therefore, it takes a lot of time to fill the defective portions of the flange portions 4 and 5 with putty and to repair the metal solder by flowing it. On the other hand, in the knurling type seam welding device, the contact peripheral surfaces of the electrode rollers 7 and 8 to which the molten zinc adheres are knurling driving wheels 11 and
The transmission tooth portions 13 and 14 of 12 are roughened and damaged, and the contact resistance of the contact peripheral surface of the electrode rollers 7 and 8 to the object to be welded is further increased. Defects increase.

Therefore, the present invention is also applicable to rust-proof plated steel sheets,
It is an object of the present invention to provide a method and an apparatus capable of performing seam welding in which welding work is easy and blowholes are not generated.

[0007]

In order to achieve the above object, the present invention provides a seam welding method according to claim 1,
The contact peripheral surface of the electrode roller that comes into contact with the object to be welded is formed by a smooth surface having a shape in which the central portion in the width direction bulges outward in the radial direction, and two pieces of the object to be welded are stacked together to form a pair. The electrode roller is pressed and sandwiched, and current is applied to the object to be welded from the electrode roller, and the portions of the objects to be welded that are in contact with each other are melted by heat generation and are joined to each other.

According to a second aspect of the present invention, in the seam welding apparatus, the overlapped objects to be welded are sandwiched by a pair of electrode rollers, and the portions of the objects to be welded that contact each other are energized from the electrode rollers. In the seam welding apparatus that melts and joins by generating heat by means of heat generation, both electrode rollers have a smooth surface having a shape in which a center portion in a width direction of a peripheral surface contacting the workpiece is bulged outward in the radial direction. Has been formed.

A seam welding apparatus according to a third aspect of the present invention is the seam welding apparatus according to the second aspect, further comprising a shaping tool having a shaping section which is recessed in a shape matching the contact peripheral surface of the electrode roller, and And a pressing means for applying an elastic force to the shaping tool to push the shaping section against the contact peripheral surface.

A seam welding apparatus according to a fourth aspect of the present invention is characterized in that the electrode roller in the seam welding apparatus according to the second aspect is provided with:
A tooth receiving portion is formed on an outer circumferential surface along at least one side of the contact circumferential surface, and a knurl driving wheel that transmits a rotational force to the electrode roller includes a transmitting tooth portion that meshes with the tooth receiving portion and the electrode roller. An escape groove portion that forms a space between the contact peripheral surface and the contact peripheral surface is provided.

[0011]

According to the seam welding method of the first aspect and the seam welding apparatus of the second aspect, the center portion in the width direction of the contact peripheral surface of the electrode roller with the workpiece is expanded outward in the radial direction. It is formed by the smooth surface of the projected shape, and the overlapped objects to be welded are sandwiched by the respective contact peripheral surfaces of the pair of electrode rollers. When electricity is applied to the object to be welded through each electrode roller, the portions of the objects to be welded that are in contact with each other generate heat and are melted, and the melted portions are pressed by the electrode rollers to join them. Here, when the object to be welded is a rust-preventive plated steel plate, the plated metal melted by energization through the smooth surface of the electrode roller is on both sides of the contact peripheral surface due to the pressure applied to the object to be welded by the electrode roller. Is eliminated and scattered. Therefore, the molten plated metal is prevented from adhering to the contact peripheral surface of the electrode roller and making the welding operation difficult. Further, the melted plated metal is significantly reduced from entering the molten portion of the welded object, and the occurrence of blowholes in the welded section due to the mixture of the plated metal can be prevented.

According to the seam welding device of the third aspect, the shaping portion of the shaping tool elastically elastically presses the smooth surface forming the contact peripheral surface of the electrode roller, that is, the surface having no unevenness such as the receiving teeth, by the pressing means. The shaping part is pressed so that it is recessed to match the smooth surface that bulges outward in the radial direction of the electrode roller, so that the plated metal that has adhered to the electrode roller can be reliably removed. Thus, the contact peripheral surface of the electrode roller is always kept smooth with a required shape. Therefore, it is possible to reliably prevent the welding work from becoming difficult due to the adhesion of the hot-dip metal to the contact peripheral surface (smooth surface).

According to the fourth aspect of the invention, in the knurl drive type seam welding apparatus, the knurl drive wheel has a receiving tooth portion whose transmission tooth portion is formed along at least one side of the contact peripheral surface of the electrode roller. The rotational force is transmitted to the electrode roller by meshing with each other, and the portion of the knurl drive wheel facing the contact peripheral surface of the electrode roller is separated by the escape groove so as to form a space with respect to the contact peripheral surface. Therefore, the smooth surface forming the contact peripheral surface of the electrode roller to the object to be welded is not roughened by the engagement of the transmission tooth portion of the knurl drive wheel, and the contact resistance of the contact peripheral surface of the electrode roller is set to the predetermined value. It can be maintained and good welding can be performed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway front view of a seam welding apparatus according to an embodiment of the present invention, and FIG. 2 is a plan view thereof. As shown in detail in FIG. 3 which is an enlarged side view of the portion A of FIG.
The contacting peripheral surface 21 to 5 is formed at its central portion in the width direction by a smooth surface having a predetermined radius of curvature R and outwardly bulging in the radial direction, that is, a surface having no unevenness such as a receiving tooth. ing.

As shown in FIG. 3, outer peripheral surfaces along both sides of the contact peripheral surface 21 are formed as inclined surfaces 22 at a predetermined angle D (for example, 45 degrees) with respect to the width direction of the electrode roller 20. Along with these inclined surfaces 22, the tooth receiving portion 2 for receiving a rotational force by a knurl drive wheel 32, which will be described later, is provided.
3 are formed. The width W of the electrode roller 20 is usually 16 to 20 mm. A force of about 400 kg is applied downwardly to the upper electrode roller 20 via a bearing portion (not shown) of the roller shaft 24 at the time of welding, and the roller shaft 24 of the lower electrode roller 20 is subjected to the above-mentioned addition. It is rotatably supported against pressure.

As shown in FIG. 1, a shaping tool 25 is individually arranged on one side of each of the electrode rollers 20. As shown in FIG. 4, which shows an enlarged plan view of the portion B of FIG. 1, the shaping tool 25 has a shaping portion 26 in which the tip center portion is recessed into a shape matching the contact peripheral surface 21 of the electrode roller 20.
The flanks 27 are formed on both sides of the shaping part 26 and are separated from the tooth receiving part 23 of the electrode roller 20. This shaping tool 25 is shown in FIG. 1 and FIG.
As shown in FIG.
While being slidably inserted in the housing 29, elastic force is applied by a coil spring (an example of a pressing means) inserted in the storage portion 29, and the shaping portion 26 is pressed against the contact peripheral surface 21 of the electrode roller 20. Has been. The elastic force applied by the coil spring 30 can be adjusted by operating the adjusting screw 31 screwed into the holding case 28 so as to move in the inserting direction or the extracting direction.

On the other side of each of the two electrode rollers 20, as shown in FIGS. 1 and 2, knurled drive wheels 32 are individually arranged. This knurled drive wheel 32 is shown in FIG.
As shown in FIG. 5 showing an enlarged plan view of the C portion, an escape groove 33 that forms a space between the central peripheral surface and the contact peripheral surface 21 of the electrode roller 20 is formed, and both sides of the escape groove 33 are formed. Further, a transmission tooth portion 34 that meshes with the receiving tooth portion 23 of the electrode roller 20 is formed. The knurl drive wheel 32 is rotated in the direction of arrow P in FIG. 1 by a rotary drive source such as a motor, and this rotational force is transmitted to the electrode roller 20 via the receiving tooth portion 23 meshing with the transmitting tooth portion 34.

Next, the operation of the above embodiment will be described. As shown in FIG. 3, two base materials 4a made of steel plate,
Plating layer 4b made of a metal such as zinc on both surfaces of 5a,
A case of welding the rust-preventive plated steel sheet having 5b as the objects to be welded 4 and 5 will be described. These objects to be welded 4, 5
Is sandwiched by the contact peripheral surfaces 21 of the pair of electrode rollers 20 each having a width of about 16 to 20 mm in the widthwise central portion which bulges outward in the radial direction, and the objects to be welded 4 and 5 are energized through the respective electrode rollers 20. To be done. At the portions of the objects to be welded 4 and 5 that contact each other, the metal plate portions 4a and 5a are melted by heat generation and welding nuggets 35 and 35 are generated. The welding nuggets 35, 35 are welded to each other by the pressing force from the upper electrode roller 20, and the objects to be welded 4, 5 are welded.

Here, the plated metal 36 melted by energization through the contact peripheral surface 21 of the electrode roller 20 is
As shown in FIG. 3, the electrode roller 20 is extruded toward both sides of the contact peripheral surface 21 by the pressure applied to the objects to be welded 4 and 5, and the plated metal 36 is provided with the teeth 23. The space between the inclined surfaces 22 on both sides escapes and scatters. In this way, the molten plated metal 36
Is scattered and eliminated on both sides, so that penetration of the objects to be welded 4, 5 into the welding nugget 35 is significantly reduced. Therefore, it is possible to prevent the blowholes from being generated due to the mixing of the plating metal 36.

Further, on the contact peripheral surface 21 of the electrode roller 20, the shaping portion 26 of the shaping tool 25 is formed.
0 is applied with an elastic force and is elastically pressed, and the shaping portion 26 has a contact peripheral surface 21 of the electrode roller 20.
Since it has a recessed shape that conforms to, the plating metal 36 attached to the contact peripheral surface 21 of the electrode roller 20 is removed by scraping. As a result, the plating metal 36 does not adhere to the contact peripheral surface 21 of the electrode roller 20, so that the increase in the electric resistance of the electrode roller 20 due to the adhesion of the plating metal is prevented and the workability of welding is improved. Maintained. Further, since the contact peripheral surface 21 of the electrode roller 20 is shaped so as to always maintain the required shape, the molten plated metal 36 is scattered and removed to the side. 5 can be prevented from entering the welding nugget 35.

In the above embodiment, the knurling type seam welding apparatus is exemplified. The knurl drive wheel 32 has its transmission teeth 32 meshed with the receiving teeth 23 formed along both sides of the contact peripheral surface 21 of the electrode roller 20.
The portion of the knurling drive wheel 32 facing the contact peripheral surface 21 of the electrode roller 20 is separated by the clearance groove 33 so as to form a space with respect to the contact peripheral surface 21. Therefore, the contact peripheral surface 21 of the electrode roller 20 that comes into contact with the objects to be welded 4 and 5 is not roughened and damaged by the engagement of the transmission tooth portion 34 of the knurl drive wheel 32 and is always in a smooth state. Retained.

FIG. 6 is a plan view showing another embodiment of the present invention. In the above-mentioned embodiment, the case where the electrode roller 20 having the width W of about 16 to 20 mm is used is illustrated, whereas in this embodiment, the case where the electrode roller 20 having the width W as small as about 10 mm is used is shown. Therefore, the electrode roller 20 is formed with the inclined surface 22 having the tooth receiving portion 23 only along one side of the contact peripheral surface 21. Corresponding to this, the shaping tool 25 is provided with a shaping portion 26 recessed in a shape matching the contact peripheral surface 21, and a flank 27 on the side portion of the forming portion 26. On the other hand, knurled wheel 3
On the second side, one transmission tooth portion 34 that meshes with the tooth receiving portion 23 of the electrode roller 20 and an escape groove portion 35 for the contact peripheral surface 21 of the electrode roller 20 are formed. The operation and effect are similar to those in the above-mentioned embodiment.

In each of the above embodiments, the plated steel sheet was used as the object to be welded, but the object of welding of the present invention is not limited to this, and even if there is no plating layer, it adheres to the contact peripheral surface of the electrode roller. The same effect can be obtained when welding to an object to be welded made of an easy metal material. Further, the present invention can be widely applied to objects to be welded by seam welding such as storage tanks of various substances and various structures, in addition to the fuel tank.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a seam welding apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of the above embodiment.

FIG. 3 is an enlarged side view of a portion A of FIG.

FIG. 4 is an enlarged plan view of portion B of FIG.

5 is an enlarged plan view of a C portion of FIG.

FIG. 6 is a plan view showing a seam welding apparatus according to another embodiment of the present invention.

FIG. 7 is a side view showing a usage state of a conventional seam welding apparatus.

[Explanation of symbols]

4, 5 ... Object to be welded, 20 ... Electrode roller, 21 ... Contact peripheral surface, 23 ... Receiving tooth portion, 25 ... Shaping tool, 26 ... Shaping portion, 32 ... Knurl drive wheel, 33 ... Relief groove portion, 34 ... Transmission tooth Part, 30 ... Coil spring (pressing means).

Claims (4)

[Claims] 1. A contact peripheral surface of an electrode roller which comes into contact with an object to be welded is formed by a smooth surface having a central portion in a width direction thereof bulging outward in a radial direction, and two overlapping objects are covered. Seam welding in which a welding object is pressed and sandwiched by a pair of the electrode rollers, and current is applied to the objects to be welded from the electrode rollers to melt the portions of the objects to be welded that are in contact with each other by heat generation to join them together. Method. 2. A seam welding apparatus for sandwiching an overlapped object to be welded with a pair of electrode rollers, and for melting and joining portions of the two objects to be welded, which are in contact with each other, by supplying heat from the electrode rollers to generate heat. The seam welding apparatus according to claim 1, wherein the both electrode rollers are formed by a smooth surface having a shape in which a center portion in a width direction of a peripheral surface contacting the object to be welded bulges outward in the radial direction. 3. The shaping tool according to claim 2, further comprising a shaping tool that is recessed in a shape that matches the contact peripheral surface of the electrode roller, and an elastic force is applied to the shaping tool to bring the shaping section into contact with the shaping tool. A seam welding device having a pressing means for pressing against the peripheral surface. 4. The knurled drive wheel according to claim 2, wherein the electrode roller is provided with a receiving tooth portion on an outer peripheral surface along at least one side of a contact peripheral surface of the electrode roller. Is
The seam welding apparatus is provided with an escape groove portion that forms a space between a transmission tooth portion that meshes with the receiving tooth portion and a contact peripheral surface of the electrode roller.