JPS6343779A - Production of welding type crankshaft - Google Patents

Abstract

PURPOSE:To easily and accurately weld and join journals mutually and to improve productivity by butting the journals mutually to tack-weld these to the specific depth from the outside periphery side and afterword, performing the main welding of a groove part in the peripheral direction while rotating a tack-welded structure. CONSTITUTION:The accurate perpendiculars are formed to the end face inner wall sides of the journal parts 4a and 4b and the end faces are butted and brought into close contact mutually. Furthermore, the outside periphery of the butting part 5 of the journal parts 4a and 4b are notched so that the U-shaped groove part 10 is formed thereto. Next, an electron beam welding means is rotated along the overall periphery of the fixed journals and the tack- welding is performed up to the depth of 8-12mm to form a tack-welded weld zone 12. Afterward, a holding tool is removed and a crank throw on one side is driven and objects to be welded are rotated to perform the multi-layer welding of the groove part 10 up to the peripheral surface by the submerged arc welding of the narrow gap.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing an assembled crankshaft, and in particular, a method for accurately and efficiently welding journal ends integrally formed on a crank arm to each other. , relates to a method of manufacturing a highly accurate rank axis.

[Prior Art] FIG. 5 is a partially cutaway side view showing an assembled type crankshaft. A pair of crank arms 2.2 and a single wooden pin 18 connecting them form a crank throw 1 which is U-shaped in side view, and about 4 to 12 crank throws 1 are connected to each other by a journal 3 with a center hole. One crankshaft is manufactured using the same process. The crank arm 2 and the journal 3 are joined by fixing the journal 3 to the journal hole 16 provided in the crank arm 2 using a shrink fit method.

However, in recent years, attempts have been made to make the crank throw longer in order to improve engine fuel efficiency, and as a result, a problem has arisen in which slippage occurs at the shrink-fit joint between the journal 3 and the crank arm 2. In order to solve this problem, it is possible to increase the thickness of the crank arm 2 and widen the shrink fit joint, but if the crank arm 2 is made thicker, the overall length of the crankshaft becomes longer, making the engine larger. It has become a disgrace.

Therefore, as another means that can sufficiently cope with the long stroke without increasing the length of the crankshaft, as shown in FIG. A method of welding the part 5 and integrating the crankshaft has been put into practical use.

[Problems to be solved by the invention] In the case of a crankshaft manufactured by welding as shown in Fig. 6, it is necessary to weld and join the crankshaft while completely preventing deformation due to welding distortion, but welding distortion occurs. Sometimes post-weld machining modifications are required, increasing manufacturing costs. Therefore, it is necessary to perform welding in a manner that does not cause welding distortion, and when performing welding, weld the entire circumference of the groove uniformly while rotating the crank throw 1, which is the welded object, in a butted state. There must be.

By the way, as equipment for rotating the crank throw, for reasons of economy and welding, a rotating device that grips and drives the crank throw on one side is commonly used, and the crank throw on the other side is connected to the crank throw on the driven side. Means such as those shown in (a) to (d) are used to temporarily fix the parts and rotate them at the same time. Of course, it is theoretically possible to use a device that rotates both crank throws together, but this is not practical because the rotating device itself would be large-scale.

(a) A method of temporarily fixing crank throws together using a mechanical or hydraulic shaft fixing device.

A shaft fixing device is inserted into the center hole 17 of the journal parts 4a, 4b, and the inner wall of the center hole 17 is pressed by mechanical or hydraulic means of the shaft fixing device to maintain a constant groove interval and fix each crank. Temporarily fix the throws to each other.

However, the shaft fixing device is heated due to welding of the groove, and the heat resistance of the backing, O-ring, etc. provided in the device becomes a problem, and there are drawbacks to durability and reliability. Furthermore, since the shaft fixing device is inserted into the center hole 17, there are dimensional restrictions, and it is difficult to ensure sufficient rigidity against the unbalanced load movement that occurs when rotating the crank throw. be.

(b) Hand welding tack using a set ring is a method.

As shown in Fig. 7(a), the left and right journal parts 4a, 4
A specially shaped set ring 6 which also serves as a backing material is fitted between b, and the set ring 6 and journal part center hole 1 are inserted.
7. Temporarily attach the corner circle portion 7 of the inner wall by hand welding.

However, in this welding, it is necessary to insert the hand into the center hole 17 to perform welding, and if the diameter of the center hole 17 is small, the arc point cannot be seen and welding must be performed by relying on intuition. Further, after the actual welding of the journal portions 4a and 4b is completed, it is necessary to cut and remove the set ring 6 using a trill or the like, which requires extra man-hours to manufacture and remove the set ring 6.

(c) Temporary attachment by welding the root part is a method.

As shown in FIG. 7(b), the journal portion 4a.

Inner wall side 10a of groove portion 10 formed at the abutting end of 4b
Welded from the outer circumference by MIG or TIG welding,
The journal parts 4a and 4b are temporarily fixed.

However, since the groove portion 10 is narrow and deep, a long nozzle must be inserted into the groove portion 10, and welding defects are likely to occur due to displacement of the arc target position due to vibration. Furthermore, since welding is performed all around the circumference in all positions, it is difficult to form a uniform Uranami bead, and only an experienced person can perform this process.

(d) Temporary attachment by internal narrow gap welding is a method.

Insert the inner surface welding device into the center hole 17 of the journal,
At a thickness of about 10 mm from the inner wall side of the center hole 17, see Fig. 7 (C).
Attach temporarily as shown. However, with this method, the thin center hole 1
The welding device must be rotated in the welding chamber 7, making it difficult to adjust the target position of the arc, making it difficult to prevent root cracking and control the bead shape.

Temporary crank throw (t) shown in (a) to (d) above
After the +-1 work is completed, the groove portion 10 is welded in multiple layers from the outer peripheral side of the journal portion by submerged arc welding while one crank throw is rotated in a cantilevered manner to complete the joining of the crank throws.

However, with the methods for temporarily fixing the crank throw described in (a) to (d) above, as explained respectively, reliable temporary fixation or temporary fixation of the journal parts cannot be expected, and it is difficult and requires special skill. It requires a lot of work and cannot be done efficiently.

Therefore, the inventors of the present invention found a way to temporarily fix the journal parts to each other in a simpler yet accurate manner when joining the journal parts that are protrudingly molded on the crank arm.
After that, various researches were carried out with the aim of providing a method for manufacturing a crankshaft that could be quickly subjected to main welding, and as a result, the present invention was completed.

[Means for Solving the Problems] The method of the present invention, which achieves the second object, involves positioning the journal ends abutting each other, and applying an electron beam temporary welding means around the butt groove. The journals are tack welded to a depth of 8 to 12 mm from the outer periphery while being rotated, and then, while the tack structure is rotated cantilevered, electron beam penetration welding means and arc welding means are used alone or in combination. The gist of this is that the groove portion is welded in the circumferential direction.

[Function] In the present invention, the ends of the journal portions to be welded are positioned in full or partial contact with each other, so the journals are accurately set in a straight line, and the subsequent tacking requires no work or work. Deformation during the main welding work is extremely unlikely to occur.

When temporarily attaching the jar reel ends positioned as described above, the electron beam welding means is rotated along the outer periphery of the journal to perform welding to a depth of 8 to 12 mm. Therefore, even if a narrow groove is formed on the outer circumferential side of the shaft for actual welding, the groove can be accurately targeted and temporary welding can be easily performed, eliminating the need for any difficult work and increasing efficiency. tasks are accomplished. Moreover, electron beam welding can be diagnosed by forming a uniform and healthy uranami bead during welding in all positions.

Further, by forming a welded portion with a depth of 8 to 12 mm, sufficient holding strength can be obtained within a practical range. That is, even in the event of unbalanced load fluctuations due to cantilever rotation of the crank throw during actual welding, accurate interlocking rotation can be performed without causing displacement on the driven side. If the outer diameter of the journal is large, the temporary welding line can be sufficiently long to match the diameter, so there is no need to increase the welding depth.

After this temporary welding, electron beam penetration welding or arc welding (including submerged arc welding) is adopted as the main welding means, but the welding conditions thereof are not limited at all.

[Example] Example 1 Figures 1 (a) to (C) have an outer diameter of 440 mm and a center hole diameter of 2.
FIG. 2 is a cross-sectional explanatory diagram showing an example of the process sequence of a method of butt welding 40 mm journal parts 4a and 4b.

First, a smooth abutment surface with a thickness of approximately 10 mm is formed on the inner wall side of the end surfaces of the journal parts 4a and 4b so as to be a plane exactly perpendicular to the axis, and the end surfaces are butted against each other to fit closely together. let Incidentally, a notch is formed on the outer periphery of the abutting portion 5 of the journal portions 4a, 4b so that a U-shaped groove portion 10 is formed.

As shown in FIG. 1(a), when the end surfaces of the journal parts 4a and 4b are butted against each other and the crank arms 2 and 2 are positioned, they are temporarily fixed by a gripping tool (not shown), and from the outer circumferential side of the groove part 10, Electron beam 1 in the direction shown by the dashed arrow
1 to perform back wave welding on the butt portion 5. The welding conditions at this time were preferably as shown below.

Acceleration voltage: 40KV.

Beam current: 150mA.

Welding speed: 60 cpm. While rotating the electron beam welding part 4 along the entire circumference of the fixed journal, a smooth Uranami bead was formed in all positions, and tack welding as shown in Fig. 1(b) was performed. A welded portion 12 is formed.

Thereafter, the gripping tool is removed and the crank throw on one side is driven to rotate the object to be welded, and the groove portion 10 is multilayer welded to the outer peripheral surface by narrow gap submerged arc welding as shown in FIG. 1(C).

Example 2 A journal portion 4a having the same size as in the first embodiment.

4b were joined in the order shown in FIGS. 2(a) to 2(C).

First, the entire end surfaces of the journal portions 4a and 4b are machined to be flush along a plane perpendicular to the axis, and both end surfaces are abutted and brought into close contact with each other to be temporarily fixed. Then, as shown in FIG. 2(a), the electron beam 11 is directed toward the abutting portion 5 from the direction shown by the broken arrow.
irradiate. The welding conditions at this time are shown in Table 1 below. The electron beam welding device is rotated along the outer circumference of the journal to form a partial weld 12 around the entire circumference of the journal to a depth of approximately 10 mm from the outer peripheral wall as shown in FIG. 2(b), and temporary welding is performed. finish.

Thereafter, the electron beam welding device is fixed in an upright position, and while the crank throw on one side is driven and rotated, penetration welding is performed under the welding conditions shown in Table 1 as shown in FIG. 2(C). That is, the main welding is completed by rotating the welding object once while forming a smooth underwave bead on the center hole 17 side.

Table 1 In the case of the method of the present invention, the butt groove surfaces of the journal parts 4a and 4b can be flat-machined as a whole, and there is no need for complicated route machining or difficult groove alignment work.

Example 3 Figures 3 (a) to (d) have an outer diameter of 692 mm and a center hole diameter of 24 mm.
It is a cross-sectional explanatory view showing a process of welding 2 mm journal parts 4a and 4b. With current technology, it may be difficult to perform penetration welding with an electron beam on a welding target whose wall thickness exceeds 100 mm. Therefore, the thickness is 1 from the inner wall side of the center hole 17.
A butt part 5 with a groove interval of 0 mm is formed up to about 00 mm, and a U-shaped groove part 10 is formed on the outer circumferential side, and the butt part 5 is formed as shown in FIG. The electron beam 11 is irradiated toward the area, and the welding device is rotated once to form a welded part 12 with a depth of about 10 mm on the outer circumferential side of the butt part 5 as shown in FIG. 3(b). Fix it.

After that, the journal parts 4a and 4b were rotated once using an electron beam welding device fixed in an upright position, and the
), a penetrating electron beam weld 13 is formed over the entire circumference. The remaining groove portion 10 is multi-layered welded to the outer peripheral surface by narrow groove submerged arc welding while rotating the journal to complete the main welding.

In the method of this embodiment, the journal portion 4a.

The end surface of 4b is 100 mm from the inner wall of the center hole toward the outer circumference.
Since it is formed as a smooth surface up to mm, the crank throws can be positioned relatively easily. At this time, as shown in FIG. 4, if a convex portion 15b is formed on a part of one end surface of the journal portions 4a and 4b and a recessed portion 15a is formed on the other end surface, the positioning work can be performed by fitting the end surfaces together. can be done even more easily.

When the crankshafts joined by the methods of Examples 1 to 3 were non-destructively inspected, no problematic welding defects were detected in any of the crankshafts.

[Effects of the Invention] The method of the present invention makes it possible to weld journals together easily and accurately, improving workability, and making the welded crankshaft highly accurate. Futa.

[Brief explanation of the drawing]

Figures 1 (a) to (C), Figures 2 (a) to (C), and Figure 3.
Figures (a) to (d) are cross-sectional explanatory diagrams showing an example of the process of the journal part joining method according to the present invention, FIG. 4 is a cross-sectional explanatory diagram showing another example of butting journal parts according to the present invention, and FIG. is a partially broken side explanatory diagram that does not show an example of conventional crankshaft manufacturing,
FIG. 6 is an explanatory cross-sectional view showing an example of producing a crankshaft according to the present invention, and FIGS. 7(a) to (c) are explanatory cross-sectional views showing a conventional method for temporarily attaching a journal portion. 1... Crank throw 2... Crank arm 3.
...Journal 4a, 4b...Journal section 5
... Butt part 6 ... Set ring 7 ...
Automatic welding part 8...Fixing tool 9...Welding part
10... Groove portion 11... Electron beam 12
... Temporary attachment +-1 welding part 13 ... Penetration welding part 1
4...Multilayer welded part 15a...Concave part 15b
...Protrusion 16...Journal hole 17...Center hole 18...Pin rotation 'J group

Claims (1)

[Claims] (1) A method of joining journals with a center hole protruding from a crank arm, in which the ends of the journals are abutted and positioned, and an electron beam tack welding means is rotated around the butt groove. The journals are then tack welded to a depth of 8 to 12 mm from the outer periphery, and then the grooves are welded by electron beam penetration welding or arc welding alone or in combination while rotating the tack structure in a cantilevered manner. A method for manufacturing a welded crankshaft, which is characterized by performing regular welding in the circumferential direction.