JPH0378200B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for positioning an aluminum alloy die-cast member and an aluminum alloy cast member when these members are welded together.

[Prior Art] Aluminum alloys are widely used in various fields as cast products by gravity casting or low pressure casting, die cast products, etc.

Die-cast products have advantages over cast products, such as higher productivity, better dimensional accuracy, less post-processing, smoother casting surfaces, and the ability to cast thinner walls, but they are extremely difficult to weld. It has the disadvantage of being

That is, since die casting involves flowing the molten metal into the mold cavity at high speed and high pressure, air intrudes into the molten metal during the transition period of the inflow, which causes the formation of blowholes. Other causes include gas generated from the mold release agent, but the main cause is the air entrainment mentioned above, most of which is scattered in a minute state that cannot be seen with the naked eye or a microscope. Its internal pressure has also become extremely high.

The above-mentioned blowholes generally occur in die-casting of light alloys, but they also occur in aluminum alloy die-casting products, and unique problems occur when inert gas arc welding is applied to such products. do. In other words, the aluminum base metal is melted to a considerable depth by the arc, and at this time, high-pressure microbubbles are heated, aggregated, and then rapidly released, resulting in blowholes due to bubble bursting at the weld bead. This may occur, or beads that should run smoothly may break. When such a phenomenon occurs at a pipe joint or a welded part of a container lid, the airtightness of the welded part is impaired, resulting in welding defects in cases such as pressure vessels and flow pipes.

Furthermore, such bubble bursting disturbs the flow of the shielding gas, making the original shielding function insufficient and causing abnormalities in the shape of the arc itself, making it difficult to obtain uniform and high-quality beads. There is a problem that I want to do.

On the other hand, aluminum alloy casting products have disadvantages such as lower productivity and poor dimensional accuracy compared to die-cast products, but on the other hand, they have the advantage of being easily welded without the high pressure and fine bubbles that die-cast products have. are doing.

[Problems to be Solved by the Invention] The present inventors took advantage of the respective advantages of aluminum alloy die-cast products and cast products to produce die-cast members and cast members, and welded them together by inert gas arc welding. I tried joining.

At that time, in order to suppress the occurrence of blowholes due to the bursting of the high-pressure microbubbles contained in the die-cast component as described above, the amount of penetration on the die-cast component side must be within a range that does not interfere with the integration of both components. in,
It is necessary to reduce it as much as possible.

As a result of research on this point, the present inventors found that
By making the welding part on the side of the die-cast part have a shape with a small heat capacity and selectively melting that part with a small amount of heat input, it is possible to weld with a small amount of penetration on the side of the die-cast part. It was discovered that it is possible to suppress the occurrence of blowholes and obtain defect-free welds with high airtightness.

When automatic welding by a welding robot is used to join a die-cast member whose welding area has a specific shape with a cast member as described above, it is necessary to adjust the penetration amount of the die-cast member to the set value. However, this requires highly accurate positioning of the die-cast member. If the positioning accuracy of die-cast parts is poor and the welding is performed at a position that deviates from the preset movement trajectory of the welding torch, there will be areas on the side of the die-cast parts where the amount of penetration is greater than the set value. Blowholes occur in the area, causing problems such as welding defects.

When the cast member is the intake manifold body and the die-cast member is the cooling water passage cover plate, positioning methods include, for example, positioning by fitting the body and cover plate together, or by temporary attachment before main welding. Possible factors include positioning. However, in the fitting method, one of the two members is a cast product with particularly poor dimensional accuracy, resulting in poor positioning accuracy. Furthermore, the tacking method increases the number of tacking steps, which reduces productivity.

In view of the above-mentioned points, the present invention provides a method for accurately positioning an aluminum alloy cast member and an aluminum alloy die-cast member without impairing productivity when welding and joining both members.

[Means for Solving the Problems] That is, the present invention combines an intake manifold A made of cast aluminum alloy for an internal combustion engine having a horizontal contact surface and a coolant passage cover plate B made of die cast aluminum alloy by welding the intake manifold A. The welding part of the cooling water passage cover plate B, which is overlapped with the surface of the part, is formed to gradually become thinner toward the tip thereof, and the outer periphery of the tip has a cross-sectional shape cut off almost perpendicularly to the surface, and welding is performed. When welding the arc toward the surface of the intake manifold A that is away from the outer periphery of the tip of the cooling water passage cover plate B, the intake manifold A is positioned on a movable work table using a setting jig, and while the cooling water passage is The cover plate B is positioned in correspondence with a clamp pin supported movably on a vertical line passing through a predetermined horizontal position with respect to the intake manifold A on the workbench positioned at the welding execution position. Using the fitting part on the cooling water passage cover plate B, at the welding position,
By vertically lowering the clamp pin and fitting it into the fitting portion of the cooling water passage cover plate B placed on the intake manifold A, the cooling water passage cover plate B is guided to a predetermined position. The present invention relates to a method for positioning a member to be welded.

[Example] Next, the present invention was applied to an intake manifold for an internal combustion engine, in which a cooling water passage cover plate made of die-cast aluminum alloy was welded to a body made of cast aluminum alloy by MIG (Metal Inert Gas) welding, which is a type of inert gas arc welding. Positioning for joining will be explained as an example.

Figure 1 is a plan view of the intake manifold, Figure 2 is a plan view of the intake manifold.
3 is a sectional view taken along the line A-A in FIG. 1, FIG. 4 is a partially enlarged bottom view of the intake manifold, FIG. 5 is an enlarged plan view of the cooling water passage cover plate, and FIG. The figure is a sectional view taken along the line B--B in FIG. 5, and FIG. 7 shows a state in which the cover plate is attached to the intake manifold for welding.

In the drawings, 1 is an intake manifold body made of aluminum alloy casting. A mounting seat 2 for the carburetor is formed on the top surface of the main body 1.
An air-fuel mixture collecting section 3 communicating with the carburetor and three branch passages 4, 5, and 6 extending from the collecting section 3 toward the intake ports of each cylinder of the internal combustion engine are provided inside. 7 is a flange for attaching the main body 1 to an internal combustion engine.

A substantially cylindrical peripheral wall 8 is integrally provided on the lower surface of the main body 1 at a portion corresponding to the lower part of the gathering portion 3, and the lower surface of the peripheral wall 8 constitutes a mating surface 9 with a cover plate described later. are doing. The inside of the peripheral wall 8 constitutes a housing 10 which is open at the bottom, and has an inlet opening into which cooling water from the cooling water jacket of the internal combustion engine flows. A baffle wall 12 is provided in the housing 10 to protrude in order to form a zigzag flow path for the cooling water.

Reference numeral 20 denotes a cover plate made of die-cast aluminum alloy for closing the housing 10, and is made slightly smaller than the outer circumference of the peripheral wall 8 of the main body 1.

The outer circumference of the cover plate 20 has a rising shape, and the upper surface of the rising part is connected to the main body 1.
It constitutes a mating surface 21 with. The cover plate 20 has a baffle wall 2 corresponding to the baffle wall 12 of the main body 1.
2 is provided, and an outlet pipe 23 for draining the cooling water that has flowed into the hanging 10 is also integrally provided.

The intake manifold is constructed by aligning the cover plate 20 with the main body 1 as shown in FIG.
It is made to be MIG welded.

FIG. 8 is an enlarged sectional view of the welded portion (for example, an enlarged partial sectional view taken along the line CC in FIG. 7). 8th
As shown in the figure, the welding area of the cover plate 20 made of aluminum alloy die-casting which is superimposed on the mating surface 9 of the main body 1 made of aluminum alloy casting is gradually thinned toward its tip. The mating surface 9 has a cross-sectional shape cut off almost vertically. During welding, welding is performed by moving the welding wire 31 of the MIG torch 30 on a surface connected to the mating surface 9 of the main body 1, which is slightly distant from the tip surface 28 of the cover plate 20. A weld as shown in FIG. 9 is thus obtained. In FIG. 9, 32 indicates a weld bead.

When using the welded joint shape, the welded part of the cover plate 20, which is a die-cast member, has a small heat capacity, and by selectively melting this part and reducing the amount of penetration, The occurrence of blowholes is suppressed and a defect-free welded part with high airtightness is obtained.

However, if the above-mentioned welded joint shape is adopted,
In order to achieve the intended purpose, it is necessary for the welding wire 31 to move on the surface of the main body 1 while keeping a constant distance D from the tip surface 28 of the cover plate 20.

In order to set the movement locus of the welding wire 31 relative to the cover plate 20 as described above, it is necessary to accurately position the cover plate 20.

Next, a positioning method that is a feature of the present invention will be explained.

FIG. 10 is a schematic explanatory diagram showing one embodiment of an apparatus for carrying out the method of the present invention.

40 is a welding robot, and the MIG torch 30 is attached to the tip of its arm 41. The welding robot 40 is driven so that the MIG torch 30 moves along a preset movement trajectory.

42 is an unwinding reel for the welding wire 31;
The welding wire 31 unwound from the reel is fed by a wire feeding device 50 at a speed according to the current value.
Supplied to MIG torch 30. 43 is a conduit cable through which the welding wire 31 is passed, and both ends thereof are connected to wire feeding devices 50, respectively.
and is fixed to the MIG torch 30.

60 is a turntable, and the turntable is turned over in a horizontal plane by a turning device 61. 62 is a jig plate, and the jig plate 62 has the intake manifold main body 1.
A setting jig 63 for positioning is attached. One side of the turntable 60 (first
The intake manifold main body 1 with the cover plate 20 placed thereon is set on the jig plate 62 (on the left side in FIG. 0), and the main body 1 is driven to the welding position by driving the reversing device 61. On the other hand, the welded intake manifold is moved to the opposite side by the above operation and taken out.

70 is a clamp pin support device, which has a cylinder 71 that is driven in the vertical direction and a cylinder 72 that is driven in the front and back direction, and a clamp pin 74 is attached to the tip of the piston rod 73 of the cylinder 72.
a and 74b are fixed. Said cylinder 7
By driving the clamp pins 1 and 72, the clamp pin 7
The upper and lower positions and the front and back positions of 4a and 74b are adjusted.

Next, positioning of a workpiece in the apparatus will be explained.

The intake manifold 1 may be positioned using a normal setting jig 63, for example, using a desired number of positioning pieces including upper and lower pins and plungers. The intake manifold 1 is positioned such that the welding portion thereof matches a preset movement locus 33 (see FIG. 7) of the welding wire 31 at the welding execution position.

Positioning of the cover plate 20 is performed as follows.

As shown in FIGS. 7 and 11, a clamp pin 74a is provided on the surface of the cover plate 20.
Cylindrical bosses 26a and 26b corresponding to 74b are provided, respectively. Clamp pin 74a,
The tip of 74b is tapered, while the corresponding boss holes 27a, 27b are shaped to approximately match the tapered portion of the clamp pin.

The clamp pins 74a and 74b are made of hard steel or the like, and are insulatedly attached to a mounting plate 75 fixed to the tip of the piston rod 73.

At the welding position, lower the clamp pins 74a and 74b as shown in FIG.
7a, 27b, the welding part of the cover plate 20 is aligned with the movement trajectory 33 of the welding wire.
Clamp pins 74a, 74b to match
and boss holes 27a, 27b are centered in advance.

When the cover plate 20 placed on the main body 1 positioned on the turntable 60 is moved together with the main body 1 to the welding position, the clamp pin 7 is driven by the cylinder 72.
4a, 74b are advanced to a predetermined position, and then lowered by driving the cylinder 71. The tapered portions of the clamp pins 74a and 74b are connected to the boss holes 2.
When descending while touching the walls of 7a and 27b,
As shown in FIG. 13, the cover plate 20
is guided by clamp pins 74a and 74b and accurately positioned at a predetermined position.

In the present invention, as described above, the main body 1, which is a cast member with poor dimensional accuracy, is positioned using a setting jig 63, and the cover plate 20, which is a die-cast member with good dimensional accuracy, is attached to a clamp pin 74a separately from the main body 1. , 74b and bosses 26a, 26
To accurately position the cover plate 20, which is a die-cast member that requires particularly accurate control of the amount of heat input and penetration from the viewpoint of preventing the occurrence of welding defects, since positioning is performed using b. I can do it.

Note that if the cover plate 20 that has been moved to the welding position is largely displaced from the main body 1, the clamp pins 74a and 74b will not fit into the boss holes 27a and 27b, making positioning impossible. Therefore, it is preferable to use positioning means for preliminarily positioning the cover plate 20 on the main body 1.

Next, an example of such preliminary positioning means will be shown. As shown in FIGS. 4 and 5, positioning pieces 13 and 14 are integrally formed on the inner circumferential surface of the peripheral wall 8 of the main body 1 at opposing positions, while the cover plate 20 has A pair of protruding pieces 24a and 24b, and 25a and 2 are provided at positions corresponding to the positioning pieces 13 and 14, respectively.
5b is integrally formed. When fitting the cover plate 20 to the main body 1, the positioning piece 13 is fitted between a pair of protrusions 24a and 24b, and the positioning piece 14 is fitted between another pair of protrusions 25a and 25b. By this,
A cover plate 20 is positioned on the main body 1.

Since the preliminary positioning means is only preliminary, particularly high accuracy is not required.

After the main body 1 and cover plate 20 are positioned at the welding position as described above, the welding robot 40 is driven to move the MIG torch 30 along a preset trajectory 33 to perform welding. Note that after welding has progressed to a certain extent and the cover plate 20 is fixed to the main body 1, the clamp pin 7
4a and 74b are raised and retreated, and the remaining parts are welded.

As described above, the welding wire 31 is unwound from the unwinding reel 42 and supplied to the MIG torch 30 by the wire feeding device 50 at a speed corresponding to the current value.
This provides a means for smoothly supplying the MIG torch 30 of No. 1.

As mentioned above, when performing MIG welding between an aluminum alloy cast member and an aluminum alloy die cast member, an aluminum alloy wire is used as the welding wire, but this wire has low strength. The diameter of the aluminum alloy wire used for MIG welding is usually about 0.8 to 1.6 mm, but when performing precision welding as mentioned above, it is desirable that the wire diameter be as small as possible without buckling the wire. For example, a diameter of about 1.2 mm is preferably used.

On the other hand, the welding wire 31 is connected to the conduit cable 43
Since the wire 31 is fed through the conduit cable 43, it is subjected to resistance due to friction with the inner wall of the conduit cable 43. Therefore, the wire feeding route is long,
Alternatively, if there is a bent portion with a small radius of curvature on the feeding path, poor feeding of the wire will occur. This tendency becomes more noticeable in the case of aluminum alloy wires with small wire diameters.

However, in the present invention, as shown in FIG. 10, the wire feeding device 50 is rotatably installed in a position where the wire feeding path above the welding robot 40 is as short as possible. It has been found that the above problem can be solved by the following.

In order to install the wire feeding device 50 in a rotatable manner, for example, the wire feeding device 50 may be rotatably attached around a rotating shaft 52 provided on a suspended support member 51. At this time, in order to enable the wire feeding device 50 to rotate with a small torque, the rotating shaft 52 is preferably provided above the center of gravity of the wire feeding device 50 and as close to the center of gravity as possible.

Further, it is preferable that the wire feeding device 50 be provided as close to the welding work as possible within a range where it does not interfere with the arm 41 of the robot 40.

With the above configuration, the wire feeding path is shortened, and since the wire feeding device 50 is rotatable, the wire 31 and the conduit cable 43 are
Due to the bending rigidity of the wire, the wire feeding path takes on the largest possible radius of curvature, resulting in good wire feeding performance.As a result, even aluminum alloy wires with small diameters can be fed smoothly. can.

[Effect of the invention] When welding and joining an aluminum alloy cast member and an aluminum alloy die-cast member,
Cast members with poor dimensional accuracy are positioned using a setting jig, and die-cast members with good dimensional accuracy are positioned using a clamp pin and a fitting part provided on the die-cast member separately from the cast member. Therefore, it is possible to accurately position a die-cast member that requires accurate control of the amount of heat input and the amount of penetration, and it is possible to obtain a welded part free of weld defects such as blowholes.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of an intake manifold to which the present invention is applied, FIG. 2 is a front view thereof,
3 is a sectional view taken along the line A-A in FIG. 1, FIG. 4 is a partially enlarged bottom view of the intake manifold, FIG. 5 is an enlarged plan view of the cooling water passage cover plate, and FIG. 7 is a plan view showing a state in which the cover plate is fitted to the intake manifold, FIG. 8 is an enlarged partial sectional view taken along line C-C of FIG. 7, and FIG. FIG. 10 is a cross-sectional view showing the welding state of the welded part, and FIG.
FIG. 13 is an explanatory view showing the state when positioning the cover plate using the clamp pin. (Main symbols in the drawing), 1: Intake manifold body made of aluminum alloy casting, 20: Cover plate made of aluminum alloy die casting, 26a,
26b: Boss, 30: MIG torch, 31: Welding wire, 40: Welding robot, 63: Setting jig, 70: Clamp pin support device, 74a, 74
b: Clamp pin.

Claims (1)

[Claims] 1 An intake manifold A made of cast aluminum alloy for an internal combustion engine having a horizontal contact surface and a cooling water passage cover plate B made of die cast aluminum alloy are superimposed on the surface of the welded part of the intake manifold A. The welding part B is formed to have a thinner wall gradually toward the tip, and the outer periphery of the tip is cut off almost perpendicularly to the surface, and the welding arc is directed from the outer periphery of the tip of the cooling water passage cover plate B. When welding to the surface of intake manifold A that is far away,
is positioned on a movable work table using a setting jig, while the cooling water passage cover plate B is positioned so as to pass through a predetermined horizontal position relative to the intake manifold A on the work table positioned at the welding position. Using the clamp pin supported movably on a vertical line and the fitting part on the cooling water passage cover plate B provided corresponding to the clamp pin, lower the clamp pin vertically at the welding position. The cooling water passage cover plate B is fitted into the fitting portion of the cooling water passage cover plate B placed on the intake manifold A to guide the cooling water passage cover plate B to a predetermined position. How to position welding parts.