JPH10252887A - Shift fork and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably improve the workability and the working accuracy without lowering rigidity of a shift fork by preventing the generation of working distortion due to a clamping force at the time of cutting a shift fork and the generation of distortion at the time of heat treatment. SOLUTION: In this shift fork 10, a tip 10c thereof and at least one side surface thereof are formed into a flat surface 10a without a stage difference, and while an arm 10f for connecting a boss 10d and the tip 10c is formed thick so as to form a reinforcing rib 10b having a geometrical moment of inertia larger than that of a conventional one. In this case, the flat surface 10a as a working reference is fixed to a working jig, and clamp is performed without deforming the shift fork 10 so as to prevent the generation of working distortion due to the clamping force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift fork and a method of manufacturing the same, and more particularly, to a shift fork having at least one side formed with a flat surface and having a cross section formed on an arm connecting the boss and the tip. By forming a reinforcing rib with a large second moment and cutting the other side using this plane as the processing reference plane, it prevents processing distortion due to clamping force during cutting and distortion during subsequent heat treatment. The present invention relates to a shift fork and a method for manufacturing the shift fork, in which the workability is greatly improved without reducing the rigidity of the shift fork, thereby facilitating the manufacture.

[0002]

2. Description of the Related Art A shift fork is a bifurcated member that engages with a groove (not shown) of a sleeve of a transmission (not shown) and slides the sleeve in the axial direction to perform a shift operation. 6 to 8, the conventional shift fork 1 has two arms 1b and 1c formed in a forked shape from a base 1a, and is fitted and fixed to a shift rod (not shown) on the base 1a. Hole 1d is formed.

The cross section of the two arms 1b and 1c is formed in a T-shape in which ribs 1e are formed on both sides in order to improve rigidity, and an engaging portion 1f which engages with a groove of the sleeve is formed in the groove. It is machined to the same size as the width of the groove and manufactured with high precision so that it can be fitted without gaps.

In the machining of the engaging portion 1f, the engaging portion 1f of the shift fork 1 is placed on the reference surface 2a of the working jig 2 in abutment, and then the holding jig 3 is brought into contact with the rib 1e. Arrow A
And fixed to the processing jig 2 by pressing in the direction, cutting both surfaces 1g and 1h of the engaging portion 1f with a milling cutter or the like, and processing the thickness of the engaging portion 1f to the same dimension as the groove of the sleeve. I have.

[0005] The shift fork 1 is fixed to the processing jig 2 with reference to one surface 1g of the engaging portion 1f and the other surface 1g.
h, the other surface 1h cannot be pressed by the holding jig 3 and only the rib 1e adjacent thereto can be pressed. Therefore, the rib pressed against the reference surface 2a of the processing jig 2 In FIG. 8, the rib 1e and the surface 1h are not flat but are formed in steps in FIG. 8, and when the holding jig 3 is pressed in the direction of arrow A, the two arms 1b and 1c are offset. , A bending moment acts in the directions of arrows B and C, respectively, and the two arms 1b and 1c are twisted,
A part of g is separated from the reference surface 2a.

[0006] As described above, the engaging portion 1f has two arms 1
Since the surface 1h is machined while b and 1c are twisted in the directions of the arrows B and C, respectively, there is a disadvantage that it is difficult to machine with high precision.

After the machining, quenching and tempering and grinding are performed.
The arms 1b and 1c of the book are further deformed by the quenching and tempering treatment, and there is a disadvantage that long-term grinding is required to correct the deformation, the workability is poor, and many man-hours are required for manufacturing.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks of the prior art, and has as its object to eliminate a step from at least one side of the tip of a shift fork. This is formed into a flat surface, and the flat surface is fixed to a processing jig with the processing reference, and the shift fork is clamped without deformation to prevent processing distortion due to clamping force, thereby preventing distortion during subsequent heat treatment. In this way, the grinding time can be significantly reduced, thereby greatly improving the workability.

Another object of the present invention is to make it possible to manufacture a shift fork with high accuracy by the above-mentioned structure, and to make it possible to engage with a groove of a transmission sleeve without looseness. The purpose of the present invention is to enable a speed change operation to be performed lightly with a small force.

Still another object is to form a shift fork by forming at least one side surface of the tip of the shift fork into a flat surface and forming a reinforcing rib on an arm connecting the boss and the tip. It is to improve workability and processing accuracy without lowering rigidity.

[0011]

In summary, the present invention (claim 1) relates to a bifurcated shift fork which engages in a groove of a sleeve of a transmission and slides the sleeve in an axial direction to perform a shift operation. At least one side surface of the tip of the shift fork that engages with the groove of the sleeve is formed as a flat surface without a step, and a reinforcing rib having a large second moment of area is provided on an arm connecting the boss and the tip. Is formed, and the other side surface of the distal end portion is cut using the plane of the distal end portion as a processing reference.

Further, the present invention provides a method for manufacturing a forked shift fork which engages with a groove of a sleeve of a transmission and slides the sleeve in an axial direction to perform a shift operation. At least one side surface of the tip end of the shift fork engaged with the groove is formed in a flat surface without a step, and after cutting the flat surface, the cut flat surface is fixed to a processing jig as a processing reference surface. Then, the other side surface of the tip is cut to prevent processing distortion due to a clamping force during the cutting process.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings. 1 to 3, a shift fork 10 according to the present invention has at least one side surface of a tip portion formed on a flat surface 10a with no step and a reinforcing rib 10b formed thereon.

The shift fork 10 is made of a high carbon steel so as to improve rigidity by quenching treatment and to improve abrasion resistance, and is forged and formed into a forked shape. (Not shown)
The sleeve is engaged with a groove (not shown) of the sleeve and assembled, and by operating a change lever, the sleeve is slid in the axial direction to perform a shift operation.

The shift fork 10 has a boss portion 10d having a diameter of about 28 mm and a fitting hole 10e having a diameter of 20 mm formed therein. A shift rod (not shown) is inserted into the fitting hole 10e and fixed. Is moved in the axial direction, so that the sleeve is slid in the axial direction via the shift fork 10 to perform the speed change operation.

From the boss 10d, two arms 10f are formed in a bifurcated manner so as to protrude in an arc shape, and a tip 10c is formed.
The height (h) (the thickness of the arm portion 10f) in the vertical direction in FIG.
Was considerably large, the height (h) of the third power in proportion to the arm portions 10f of the second moment I (I = bh ^3/12
Here, b is thickened so as to increase the width of the arm portion 10f) to form a reinforcing rib 10b, so that the bending strength of the arm portion 10f is not reduced as compared with the conventional case.

The tip 10c has an L-shaped cross section in which a flat surface 10a having no step is formed from one side surface, and the distance between the two tips 10c is, for example, 189.5 m.
m, and the thickness is 12 mm.
c is engaged with the groove of the sleeve and assembled, and the thickness of the tip portion 10c is machined with high precision and finished so as to fit into the groove of the sleeve without looseness.

The method of manufacturing a shift fork according to the present invention is directed to a method of manufacturing a forked shift fork 10 which engages with a groove of a sleeve of a transmission and slides the sleeve in an axial direction to perform a shift operation. At least one side surface of the tip 10c of the shift fork 10 that engages with the groove of the shift fork 10 is formed on a plane 10a, and after the plane 10a is cut, the processing jig 11 is used as a processing reference plane with the cut plane 10a as a processing reference plane. This is a method in which the other side surface 10g of the distal end portion 10c is fixed and cut to prevent the processing distortion due to the clamping force during the cutting process.

The present invention is configured as described above,
Hereinafter, the operation will be described. Although the thickness of the tip portion 10c is about 12 mm, it is necessary to finish it with high precision in order to make it engage with the groove of the sleeve without looseness, and machining is performed. 4
In FIG. 5, first, the fitting hole 11 e is formed into a predetermined hole diameter, and further, the flat surface 10 a is formed into a flat shape by cutting such as milling, and then the fitting hole 10 e is formed into the processing jig 11.
The rib 10b is fixed to the processing jig 11 by pressing the rib 10b in the direction of the arrow D with the holding jig 12 by inserting the flat surface 10a into contact with the reference surface 11b.

The other side surface 10g of the flat surface 10a is cut into a flat shape by milling or the like using the flat surface 10a as a processing reference surface. Presser jig 12
As a result, the arm portion 10f is not distorted by the clamping force, so that the processing distortion is prevented.

The shift fork 10 is subjected to quenching and tempering after both surfaces 10a and 10g of the tip 10c are cut, so that at least the tip 10c has a hardness of about 700 Vickers hardness. Although both surfaces 10a and 10g of the tip portion 10c are processed to predetermined dimensions by grinding, they are completed. However, since the processing distortion due to the clamping force at the time of cutting is prevented as described above, the grinding allowance can be reduced, and it is easy. Can be manufactured.

[0022]

As described above, according to the present invention, a step is formed on at least one side surface of the tip end of the shift fork so as to form a flat surface, and the flat surface is fixed to a processing jig using the flat surface as a processing reference. Clamping without deformation to prevent processing distortion due to clamping force,
Distortion during the subsequent heat treatment can be prevented, and as a result, the grinding time can be significantly reduced, so that the workability can be greatly improved.

Further, with the above structure, the shift fork can be manufactured with high precision and can be engaged with the groove of the transmission sleeve without looseness, so that the speed change operation can be performed lightly with a small force. This has the effect.

Further, at least one side surface of the tip end of the shift fork is formed in a flat surface without a step, and the arm connecting the boss portion and the tip end is formed with a reinforcing rib which is thicker than in the prior art. There is an effect that the workability and the processing accuracy can be improved without reducing the rigidity of the fork.

[Brief description of the drawings]

FIGS. 1 to 5 relate to an embodiment of the present invention, and FIG. 1 is a perspective view of a shift fork.

FIG. 2 is a plan view of a shift fork.

FIG. 3 is a vertical sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a perspective view showing a state in which a shift fork is fixed to a processing jig by a holding jig.

FIG. 5 is a front view showing a state in which a shift fork is fixed to a processing jig by a holding jig.

FIGS. 6 to 8 relate to a conventional example, and FIG. 6 is a perspective view showing a state in which a shift fork is fixed to a processing jig by a holding jig.

FIG. 7 is a front view showing a state in which the shift fork is fixed to a processing jig by a holding jig.

FIG. 8 is a front view showing a state in which a shift fork is twisted by a clamping force and fixed to a processing jig.

[Explanation of symbols]

 Reference Signs List 10 shift fork 10a plane 10b rib for reinforcement 10c tip 10d boss 10f arm 10g other side surface 11 processing jig

Claims (2)

[Claims] 1. A forked shift fork which engages with a groove of a sleeve of a transmission and slides the sleeve in an axial direction to perform a shift operation, and a tip portion of the shift fork which engages with the groove of the sleeve. At least one side surface is formed in a flat surface without a step, and a reinforcing rib having a large second moment of area is formed in an arm portion connecting the boss portion and the tip portion, and the plane of the tip portion is used as a processing reference. A shift fork, wherein the other side surface of the tip portion is cut. 2. A method for manufacturing a forked shift fork, which engages with a groove of a sleeve of a transmission and slides the sleeve in an axial direction to perform a shift operation, wherein the shift fork engages with the groove of the sleeve. At least one side surface of the tip portion is formed as a flat surface without a step, and after cutting the flat surface, the cut surface is fixed to a processing jig as a processing reference surface, and the other side surface of the tip portion is formed. A method for manufacturing a shift fork, comprising cutting a workpiece and preventing machining distortion due to a clamping force during the cutting.