JP2004090181A - Manufacturing method of differential case of differential gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve technology of cutting a partially spherical seat surface for receiving pinion in a manufacturing method of a differential case of a differential gear. <P>SOLUTION: A cutting tool 20 mounted to a spindle of a machining center is inserted into the differential case 1 from one of opening windows 12, the axial center 24 of the cutting tool 20 is cut in a state of directed orthogonally to a pinion axial center and the axial center of a side gear, and the axial center of the cutting tool 20 is moved along a partially cylindrical surface 25. Thus, the partially spherical seat surface 7 for the pinion for receiving the pinion is cut in the inner wall 6 of the differential case by the general machining center and the cutting tool 20. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a differential case of a differential gear, and more particularly to an improved method of cutting a partially spherical bearing surface for receiving a pinion on an inner surface of the differential case.
[0002]
2. Description of the Related Art For example, a two-pinion type differential device has a differential gear mechanism including a pair of left and right side gears and a pair of pinions, and a differential case for accommodating the differential gear mechanism. In manufacturing the differential case, first, in a casting process, a differential case having a pair of opening windows is cast, and then, a hole of a journal portion supporting an axle, a shaft hole through which a pinion shaft passes, and a pinion inside the differential case are formed. It is manufactured by cutting the seat surface to receive and the seat surface to receive the side gear. However, in this cutting process, since the seat surface receiving the pinion is partially spherical, it is not easy to cut the seat surface, and various techniques for cutting the seat surface receiving the pinion have been adopted. ing.
[0003]
For example, as shown in FIGS. 3 (a) to 3 (c), a pair of tool spindles 52 of the special-purpose machine is inserted from both shaft holes 51 for a pair of pinion shafts in the differential case 50, and then, The cutting tool 53 is introduced into the differential case 50 from the opening window 55, and a partially spherical cutting tool 53 whose inner wall side is the same as the pinion seat surface 54 is attached to the tip of the tool spindle 52, and the tool spindle 52 is attached. A manufacturing method in which the pinion seat surface 54 is formed by rotating and cutting the inner wall portion of the differential case 50 with the back surface of the cutting tool 53 is also employed.
[0004]
Alternatively, as shown in FIG. 4, a bit 62 of an NC lathe, the tip of which is bent by about 90 degrees, is inserted from a hole 61 of a journal portion supporting an axle of a differential case 60, and the bit 62 A manufacturing method of forming a pinion seating surface 63 by cutting the portion corresponding to the pinion seating surface of the inner peripheral portion of the differential case 60 and moving the cutting tool 62 relative to the differential case 60 with a predetermined locus. ing.
Patent Document 1 discloses a manufacturing technique for manufacturing a differential case of a differential device, but this manufacturing technique relates to a casting technique for casting a differential case, and relates to a cutting technique for the pinion seat surface. Is not described at all.
[0005]
[Patent Document 1] Japanese Patent Application Laid-Open No. 9-229163
However, in the manufacturing method shown in FIGS. 3A to 3C, the cutting tool at the tip is larger than the shaft hole for the pinion shaft. The cutting tool must be removed from the tool spindle after the cutting of the pinion seat surface has been completed after the cutting tool is attached to the tip of the tool spindle. It takes a lot of labor and time to prepare and finish the cutting work of the seat. In addition, since a general-purpose processing machine cannot be applied to the special-purpose processing machine, a special-purpose processing machine having a special structure is required, which is disadvantageous in terms of equipment cost.
[0007]
On the other hand, the manufacturing method shown in FIG. 4 has a problem that the size of the insertable bit is limited by the diameter of the hole of the journal portion. If the hole in the journal is small, the cutting tool cannot be cut because the cutting tool does not reach the inner wall, and cutting may not be possible depending on the shape of the seat for the pinion.It is applicable to all differential cases. It is not a technology. Also in the control of the NC lathe, it is necessary to move the cutting tool two-dimensionally with respect to the differential case, so that the control in the NC lathe is complicated. Since cutting is performed with a cutting tool, it is difficult to increase the cutting efficiency, and it takes a lot of time for cutting.
An object of the present invention is to provide a method of manufacturing a differential case of a differential device capable of easily and efficiently cutting a partially spherical pinion seating surface.
[0008]
According to a first aspect of the present invention, there is provided a method for manufacturing a differential case for a differential, comprising: a pair of side gears, a pair of pinions mounted between the side gears, and a differential case accommodating the side gears and the pinions. In the method for manufacturing the differential case in the differential including: a pair of connecting wall portions for forming a shaft hole of a pinion shaft supporting a pinion in a peripheral wall portion of the differential case when casting the differential case. And a first step of forming a pair of open windows, which are a pair of open windows opened between the pair of connecting wall portions, for incorporating a side gear and a pinion, and cutting attached to a main shaft of the machining center. A tool is inserted into the differential case through one of the opening windows, and the machining center and the cutting tool are used to define a partially spherical bearing surface for receiving the pinion. It is characterized in that a second step of cutting the inner wall portion of the scan.
[0009]
In the first step of the method for manufacturing the differential case of the differential device, when the differential case is cast, a pair of connecting walls and an opening 1 between the pair of connecting walls are formed on the peripheral wall of the differential case. Form a pair of open windows. Next, in the second step, a cutting tool attached to the main shaft of the machining center is inserted through one of the opening windows to cut a partially spherical pinion seat surface for receiving a pinion on the inner wall portion of the differential case. Process.
[0010]
In the second step, the cutting tool attached to the main shaft of the machining center is inserted from the opening window that can be formed much larger than the shaft hole for the pinion shaft, so there is no restriction on the shape or size of the cutting tool. In addition, a general-purpose machining center can cut a seating surface for a pinion. In addition, since there are few restrictions on cutting tools, it is possible to use cutting tools that have a shape corresponding to the partially spherical bearing surface of the pinion, so the trajectory of the cutting tool at the time of cutting is simplified, and cutting efficiency is improved. Is also possible, and the production cost can be significantly reduced.
[0011]
According to a second aspect of the present invention, in the manufacturing method of the differential case according to the first aspect, in the second step, the axis of the cutting tool is perpendicular to the axis of the pinion shaft and the axis of the side gear. It is characterized in that cutting is performed in a state of facing. In this manufacturing method, since the cutting is performed in a state where the axis of the cutting tool is directed in a direction orthogonal to the axis of the pinion shaft and the axis of the side gear, initial setting such as setting the origin position of the cutting tool is easy. In addition, cutting accuracy can be improved.
[0012]
According to a third aspect of the present invention, in the manufacturing method of the differential case according to the second aspect, in the second step, cutting is performed while moving an axis of the cutting tool along a partial cylindrical surface. It is assumed that. In this manufacturing method, since only the axis of the cutting tool needs to be moved along the partial cylindrical surface, the position control for controlling the position of the cutting tool is simplified.
[0013]
Embodiments of the present invention will be described below with reference to the drawings. However, the description will be made with the upper, lower, left and right in FIG.
The present embodiment is a differential device for transmitting the driving force of an engine of an automobile to left and right front wheels, and includes a pair of side gears, a pair of pinions mounted between the side gears, and a pair of the side gears and the pinion. This is an example of a case where the present invention is applied to a method of manufacturing a two-pinion differential including a differential case for accommodating the present invention.
[0014]
First, the differential case 1 of the differential will be described.
As shown in FIGS. 1 and 2, the differential case 1 includes a flange 2 for mounting a ring gear, holes 3 a and 3 b of left and right journals, a peripheral wall 4, and the like. , A partially spherical seating surface 7 for receiving a pinion, a seating surface 8 for receiving a side gear, and the like.
[0015]
A shaft hole 10 for a pinion shaft for inserting and supporting a pinion is formed in the peripheral wall portion 4 of the differential case 1 and has a pair of connecting wall portions 11 opposed to each other. , A pair of opening windows 12 for incorporating a side gear and a pinion are formed to face each other. The flange 2 has a bolt hole 13 for attaching a ring gear and a positioning hole 14 for positioning when attaching to a differential device. A pin hole 15 for a spring pin for fixing the pinion shaft to the differential case 1 is formed in the connecting wall portion 11 and the flange 2. A spiral oil groove 16 is formed on the inner peripheral surfaces of the holes 3a and 3b of the journal. However, the oil groove 16 is not always necessary and can be omitted as appropriate.
[0016]
Next, a method for manufacturing the differential case 1 will be described with reference to FIGS. First, in the first step, the differential case 1 is manufactured by casting using a material of spheroidal graphite cast iron. At the time of this casting, a pair of connecting wall portions 11 for forming a shaft hole 10 through which a pinion shaft for supporting a pinion is formed in the peripheral wall portion 4 of the differential case 1, and between the pair of connecting wall portions 11. A pair of large opening windows 12 for incorporating a side gear and a pinion are formed as a pair of opening windows 12 to be opened, and holes 3a and 3b of the journal portion are formed. In the state cast in the first step, the peripheral wall portion 4, the holes 3a and 3b, and the portion of the seating surface 7 for the pinion inside the differential case 1 are about 1 to 2 mm for cutting later. Extra cutting allowance is left.
[0017]
Next, in the second step, the outer surface side and the inner surface side of the differential case 1 are cut by a machining center. However, the portions other than the pinion seating surface 7 are processed by a general cutting method, and thus will be briefly described. First, the hole 3b of the right journal, the outer peripheral surface 2a of the flange 2, the corner 4a of the right peripheral wall 4 of the flange 2, and the like are cut by an NC lathe. At this time, the oil groove 16 is also cut by the NC lathe on the inner peripheral surface of the hole 3b of the journal portion.
[0018]
Next, the differential case 1 is detached from the NC lathe, and is mounted on the NC lathe in the left-right direction, and the hole 3a of the left journal portion, the oil groove 16 of the inner peripheral surface thereof, and the corner portion 4 of the left peripheral wall portion 4 of the flange 2 are formed. F is cut by an NC lathe. Next, one or two positioning holes 14 are cut in the flange 2 by the machining center, and a plurality of bolt holes 13 at appropriate intervals in the circumferential direction are cut.
[0019]
Next, the tool spindle fixed to the spindle of the special-purpose processing machine is inserted from the holes of both journals, and a cutting tool corresponding to the side gear seat surface is attached from the inside of the differential case to the tip of the tool spindle. After a part of the inner wall portion 6 of the differential case is cut by a tool to form a pair of side gear seating surfaces 8, a pair of shaft holes 10 for a pinion shaft and a pair of spring holes for a spring pin are again formed by the machining center. Is formed.
[0020]
Next, a partially spherical pinion seating surface 7 for receiving the rear side of the pinion is cut by a general-purpose machining center. When cutting the partially spherical bearing surface 7 receiving the pinion, a cutting tool 20 fixed to the main shaft of the machining center is inserted into the differential case 1 from one of the opening windows 12 of the differential case 1. As shown in FIG. 2, this cutting tool 20 is a kind of end mill in which a barrel-shaped blade portion 21 and a shaft portion 22 on the tip side are integrally formed, and the blade portion 21 is formed on a barrel-shaped outer peripheral surface for cutting. The spiral cutting blade 23 is formed. The shape of the outer peripheral surface of the blade portion 21 is set according to the shape of the pinion seat surface 7 to be cut. That is, the blade portion 21 capable of cutting the pinion seating surface 7 is employed.
[0021]
Next, while the cutting tool 20 inserted into the differential case 1 is oriented such that the axis of the cutting tool 20 is oriented in a direction orthogonal to the axis of the pinion shaft and the axis of the side gear, respectively, the axis 24 of the cutting tool 20 is cut. Is cut along while moving along the partial cylindrical surface 25 as shown in FIG. 1 to form the pinion seating surface 7. After the second step, the differential case 1 of the differential device is completed through a finishing step of performing deburring and the like.
[0022]
Next, the operation and effect of the above-described method for manufacturing the differential case of the differential will be described. When casting the differential case 1 in the first step, a pair of connecting wall portions 11 and a pair of opening windows 12 opened between the pair of connecting wall portions 11 are formed in the peripheral wall portion 4 of the differential case 1. Then, in the second step, the cutting tool 20 attached to the main shaft of the machining center is inserted through any one of the opening windows 12, and the partial spherical seating surface 7 that receives the pinion on the inner wall portion of the differential case 1. To cut.
[0023]
Next, in the second step, since the cutting tool 20 is inserted from the opening window 12 which is much larger than the shaft hole 10 through which the pinion shaft passes, there are few restrictions on the shape and size of the cutting tool 20, and the outer peripheral surface is barrel-shaped. The pinion seating surface 7 can be cut by using a relatively large cutting tool 20 having a blade 21 having a shape, and the pinion seating surface 7 can be accurately and efficiently formed by a general-purpose machining center. Can be machined.
[0024]
Preparing work is simplified by performing cutting using a cutting tool 20 having the barrel-shaped blade portion 21 as described above and adapted to the partial spherical surface of the pinion seating surface 7. Since the contact machining surface of the cutting tool 20 can be enlarged, cutting efficiency can be remarkably improved, and the axis 24 of the cutting tool 20 need only be controlled to a simple trajectory like the partial cylindrical surface 25. The control technology for controlling the position of the vehicle is also simplified. Since the cutting is performed in a state where the axis 24 of the cutting tool 20 is oriented in a direction orthogonal to the axis of the pinion shaft and the axis of the side gear, initial setting such as setting of the origin position of the cutting tool 20 is also facilitated.
[0025]
The method for manufacturing the differential case according to the present invention is not limited to the technique of the above-described embodiment. For example, in the second step, the order of the cutting steps of each part is changed, a differential case is manufactured with an iron-based metal material other than spheroidal graphite cast iron, and the shape of the blade 21 of the cutting tool 20 is not limited to the above. Depending on the shape and the like of the cutting tool 20, the axis 24 of the cutting tool 20 can be moved along a surface other than the partial cylindrical surface 25.
[0026]
According to the method for manufacturing a differential case of a differential device according to the first aspect, when the differential case is cast in the first step, a pair of connecting walls and a pair of connecting walls are formed on the peripheral wall of the differential case. After forming a pair of open windows that open between the connecting wall portions, in a second step, a cutting tool attached to the main shaft of the machining center is inserted through one of the open windows, and the inner wall of the differential case is opened. The partially spherical bearing surface that receives the pinion in the portion can be cut efficiently and accurately.
[0027]
In the second step, the cutting tool is inserted from the opening window, which is much larger than the shaft hole for the pinion shaft, so there are few restrictions on the shape and size of the cutting tool, making it possible to perform cutting with a general-purpose machining center. Become. Since there are few restrictions on the shape and size of the cutting tool, it is possible to perform cutting with a cutting tool that has a shape corresponding to the partially spherical bearing surface that receives the pinion, reducing preparation work for control processing and finishing work. In addition, the cutting accuracy can be increased, the cutting efficiency can be increased, and the manufacturing cost can be significantly reduced. Also, the position control of the cutting tool in the cutting process is simplified, and depending on the shape of the cutting tool, it is possible to set a large contact processing surface during the control process, so that the time required for the cutting process can be further reduced, and the manufacturing cost Can be further reduced.
[0028]
According to the method for manufacturing a differential case of a differential gear according to claim 2, since the cutting is performed in a state where the axis of the cutting tool is oriented in a direction orthogonal to the axis of the pinion shaft and the axis of the side gear, respectively. Initial setting such as setting of the origin position of the lens can be simplified, and the cutting accuracy can be improved.
According to the method of manufacturing a differential case for a differential gear according to claim 3, since it is only necessary to move the axis of the cutting tool along the partial cylindrical surface while rotating the cutting tool, a control technique for controlling the position of the cutting tool is provided. It's easy.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a differential case for explaining a method of cutting a seating surface for a pinion according to an embodiment of the present invention.
FIG. 2 is a sectional view taken along line II-II of FIG.
3 (a) to 3 (c) are views for explaining a conventional method of cutting a seating surface for a pinion.
FIG. 4 is a view for explaining another conventional method of cutting a seating surface for a pinion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Differential case 2 Flange 4 Peripheral wall part 6 Inner wall part 7 Seat surface which receives pinion 8 Seat surface which receives side gear 10 Shaft hole 11 which passes pinion shaft 11 Connecting wall part 12 Window 20 Cutting tool 24 Cutting tool axis 25

Claims (3)

A method of manufacturing the differential case in a differential including a pair of side gears, a pair of pinions mounted between the side gears, and a differential case accommodating the side gears and the pinions,
When the differential case is cast, a pair of connecting wall portions for forming a shaft hole through which a pinion shaft for supporting a pinion is formed in a peripheral wall portion of the differential case, and an opening formed between the pair of connecting wall portions. A first step of forming a pair of open windows for incorporating a side gear and a pinion, the pair of open windows;
A cutting tool attached to the main shaft of the machining center is inserted into the differential case from one of the opening windows, and the machining center and the cutting tool cut a partially spherical bearing surface for receiving a pinion on the inner wall portion of the differential case. Two steps,
A method for manufacturing a differential case for a differential, comprising: 2. The differential gear according to claim 1, wherein in the second step, the cutting is performed in a state where the axis of the cutting tool is directed in a direction orthogonal to the axis of the pinion shaft and the axis of the side gear, respectively. 3. A method for manufacturing a differential case of an apparatus. 3. The method according to claim 2, wherein in the second step, the cutting is performed while moving an axis of the cutting tool along a partial cylindrical surface. 4.

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