JP2654301B2 - Centerless grinding method for stepped workpieces - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention performs centerless grinding of a stepped workpiece having a large-diameter cylindrical surface, a small-diameter cylindrical surface concentric with the large-diameter cylindrical surface, and a conical surface connecting the two cylindrical surfaces. It is about the method. However, in the present invention, the conical surface is intended to include a case where the apex angle is 180 degrees at the maximum (that is, a plane perpendicular to the axis).

[0002]

2. Description of the Related Art FIGS. 3A and 3B show a conventional example of centerless grinding of a stepped columnar workpiece 1. FIG. 3A is a schematic plan view, and FIG. Since the workpiece 1 has a relatively large-diameter cylindrical surface (abbreviated as a large-diameter portion) 1a and a relatively small-diameter cylindrical surface (abbreviated as a small-diameter portion) 1b, the grinding wheel 2 is also adjusted in accordance with this. 3 also has a small diameter portion and a large diameter portion. Workpiece 1 is blade 4
The large-diameter portion of the adjusting grindstone 3 and the large-diameter portion of the grinding grindstone 2 slide against the small-diameter portion 1b of the processing portion 1 and are supported by the small-diameter portion 1b.
b, the small-diameter portion of the adjusting grindstone 3 and the small-diameter portion of the grinding wheel 2 slide on the large-diameter portion 1a of the workpiece 1 to perform centerless grinding of the large-diameter portion 1a. Done. 5 is a drive mechanism for the grinding wheel 2, and 6 is a drive mechanism for the adjustment wheel 3, each of which has a structure capable of arbitrarily adjusting the rotation speed.

[0003]

In the prior art centerless grinding described with reference to FIG. 3, a stepped integral grinding wheel and a stepped integral adjusting grinding wheel are used in accordance with the shape and dimensions of a stepped workpiece. However, the peripheral speed adjustment of the grinding wheel for grinding the large diameter portion of the workpiece and the peripheral speed adjustment of the grinding wheel for the grinding of the small diameter portion cannot be performed independently.
For this reason, a difference in the diameter of the grindstone corresponding to the diameter difference between the large-diameter portion and the small-diameter portion of the stepped workpiece causes a peripheral speed difference, which gives an unstable factor during grinding. In particular, since the adjusting grindstone is a member that controls the rotational speed of the workpiece, slipping between the workpiece and the adjusting grindstone is not preferable because it adversely affects machining accuracy. In order to prevent a decrease in processing accuracy due to a difference in peripheral speed between the large diameter portion and the small diameter portion, a grinding wheel for a large diameter portion for grinding a large diameter portion of a workpiece and a grinding wheel for a small diameter portion are used. The grinding wheel for the small diameter part is configured as a separate body, each grinding wheel is individually driven and controlled for rotation, and the large diameter part of the workpiece is supported by the adjustment grinding wheel and blade dedicated to the large diameter part, It is conceivable that the small diameter portion of the workpiece is supported by a shoe and a blade, which are stationary members. Such a centerless grinding method and a grinding apparatus for stepped workpieces were invented by the present inventor, and have been separately filed by the present applicant (Japanese Patent Application No. 3-344232, hereinafter referred to as the prior invention). Say). In the centerless grinding according to the invention of the prior application, a large-diameter portion grinding wheel for grinding a large-diameter portion of a workpiece and a small-diameter portion grinding wheel for grinding a small-diameter portion are rotationally driven and controlled independently of each other. Therefore, each of the large-diameter portion and the small-diameter portion of the workpiece can be ground at an appropriate peripheral speed, and the disadvantage of the prior art that the processing accuracy is reduced due to the peripheral speed difference is eliminated. FIG. 4 shows an embodiment of the centerless grinding apparatus according to the invention of the prior application, and FIG.
FIG. 3A is a schematic plan view corresponding to FIG. 3A, and FIG. 3B is a schematic front view corresponding to FIG. 3B. The first grinding wheel (G1) 7 for large-diameter portion grinding and the second grinding wheel (G2) 8 for small-diameter portion grinding are formed separately, and the rotation speed is adjusted by independent drive mechanisms 12a and 12b. It is driven to rotate as much as possible (the rotational speed can be adjusted, so the peripheral speed of the grindstone can be set arbitrarily). FIG. 5 is a schematic diagram showing an example of implementing the centerless grinding method according to the invention of the prior application using the centerless grinding apparatus for stepped parts (FIG. 4) according to the invention of the prior application, and FIG. ) Depicts the ready state for the grinding operation. In FIG. 5, illustration of the blades is omitted to simplify the drawing. The material 1 'to be subjected to the grinding process is sent as shown by an arrow g. At this time, the first grinding wheel (G1) 7 and the adjusting wheel (RW) 9 for grinding the large-diameter portion are opposed to each other in the same manner as in the case where the large-diameter portion of the workpiece is centerlessly ground in a normal method. . The second grinding wheel (G2) 8 for grinding a small-diameter portion, which can be moved in the radial direction as indicated by a reciprocating arrow b, has a surface s on the side facing the workpiece with the surface of the first grinding wheel (G1) 7. Aligned with s' or slightly retracted. The shoe 10 is set at a position suitable for the radius r of the small diameter portion of the workpiece.
After the preparation as described above, as shown in FIG. 5 (B), the adjusting grindstone (RW) 9 is cut and fed in the direction of arrow a, and the first grinding grindstone (G1 ) 7 to grind the large diameter portion 1a. At this stage, the large-diameter portion 1a is supported by the adjusting grindstone (RW) 9 and a blade (not shown), and is ground by the first grinding grindstone (G1) 7 while the cross-section is formed by a circular forming effect peculiar to centerless grinding. The grinding proceeds so that the circle becomes a perfect circle. When the centerless grinding state of the large diameter portion 1a is stabilized, the second grinding wheel (G
2) 8 is cut and fed in the direction of arrow b ', and the centerless grinding of the small diameter portion 1b of the workpiece 1 is performed while being supported by the shoe 10 and a blade (not shown). In the above-described grinding operation, the rotation speed of the first grinding wheel (G1) 7 for grinding the large diameter portion is controlled by the drive mechanism 12a so as to have an appropriate peripheral speed for grinding the large diameter portion 1a. The rotation speed of the second grinding wheel (G2) 8 for grinding the small diameter portion is controlled by the drive mechanism 12b so that the peripheral speed becomes appropriate for grinding the small diameter portion 1b. As described above, the large diameter portion and the small diameter portion of the workpiece are each subjected to centerless grinding under optimum conditions, and the problem of slippage due to the peripheral speed difference as described in the conventional example of FIG. 3 does not occur. Therefore, the large diameter portion and the small diameter portion are centerlessly ground in a stable state, and high accuracy is obtained.
In the above-mentioned grinding operation, the finishing dimension of the large-diameter portion 1a of the workpiece is adjusted by the infeed of the adjusting grindstone (RW) 9 in the direction of the arrow a. In addition, the setting position of the shoe 10 is adjusted in accordance with the finishing size of the small diameter portion 1b, and the cutting feed of the second grinding wheel (G2) for the small diameter portion in the direction of the arrow b 'is performed at a position where the desired size is obtained. Stop. As described above, the dimensions of the large-diameter portion 1a and the small-diameter portion 1b can be adjusted, so that even if the specifications of the workpiece (the diameters of the large-diameter portion and the small-diameter portion) change, it is possible to cope without changing the grinding wheel. be able to. When the first grinding wheel (G1) 7 and the second grinding wheel (G2) 8 are worn out and need to be replaced, the first grinding wheel (G1) 7 is moved to an arrow c.
In the direction, and separated from the second grinding wheel (G2) 8 to perform an exchange operation. If the grinding wheel can be moved in the axial direction (for example, the direction of arrow c) as described above, it is possible to easily cope with the case where the large diameter portion and the small diameter portion of the workpiece are separated in the longitudinal direction. It is convenient. The centerless machining apparatus for a stepped workpiece according to the invention of the prior application described above with reference to FIGS.
The centerless grinding is performed by the grinding wheel (G1) 7 and the adjustment grinding wheel (RW) 9 and the small diameter portion of the workpiece is centerless ground by the second grinding wheel (G2) 8 and the shoe 10. However, based on the same technical idea, it is conceivable to grind the small diameter portion with the second grinding wheel (G2) and the adjustment grindstone dedicated to the small diameter portion without using a shoe. This configuration has been devised by the inventor, and has been separately filed by the present applicant (Japanese Patent Application No. Hei 4-1685, hereinafter referred to as the prior invention). In the centerless grinding device according to the invention of the prior application, the large-diameter portion grinding wheel for grinding the large-diameter portion of the workpiece and the small-diameter portion grinding wheel for grinding the small-diameter portion are rotationally driven and controlled independently of each other. In addition, the adjusting grindstone for the large diameter portion and the adjusting grindstone for the small diameter portion are rotationally driven and controlled independently of each other, so that the large diameter portion
Each small diameter part can be ground at an appropriate peripheral speed,
The same effect as in the invention of the prior application (prevention of reduction in processing accuracy due to difference in peripheral speed) can be obtained. FIG. 6 shows an embodiment of the centerless grinding apparatus according to the invention of the prior application, and FIG. 6 (A) is a schematic plan view showing FIG.
It is a figure corresponding to (A). FIG. 6B is a schematic front view, and FIG.
It is a figure corresponding to (B). FIG. 6 shows the stepped workpiece 1.
As shown in (B), it is supported from below by the blade 4. The first grinding wheel (G1) 7 for the large-diameter portion and the second grinding wheel (G2) 8 for the small-diameter portion of the workpiece 1 are rotationally driven independently of each other by drive mechanisms 12a and 12b. Controlled. Further, the adjusting grindstone (RW) 9 for the large diameter portion and the adjusting grindstone (RW ') 10' for the small diameter portion are rotationally driven and controlled independently by the driving mechanisms 13 and 14, respectively. In this way, each grindstone can be rotated at any desired peripheral speed.
The large-diameter portion adjusting grindstone (RW) 9 and the small-diameter portion adjusting grindstone (RW ') 10' can be cut and fed as indicated by reciprocating arrows a and b, respectively. Instead of making the adjustment whetstone cut and fed as described above,
The grinding wheel (G1) 7 for the large-diameter portion and the grinding wheel (G2) 8 for the small-diameter portion may be configured to be cut and fed as indicated by reciprocating arrows a 'and b'. Centerless grinding device according to the invention of the earlier application configured as described above (FIG. 6)
According to this, centerless machining with high accuracy can be performed at the optimum peripheral speed for both the large diameter portion and the small diameter portion of the stepped workpiece. In the embodiment shown in FIG. 6, the grinding wheel (G1) 7 for the large diameter portion and the adjusting grinding wheel (RW) 9 for the large diameter portion are configured to be movable in the axial direction as indicated by the reciprocating arrows c and d, respectively. It is. With this configuration, it is convenient to perform a whetstone replacement operation. Instead of the configuration in which the grinding wheel for the large diameter portion can be moved in the axial direction as described above, the grinding wheel (G2) 8 for the small diameter portion and the adjusting grinding wheel (RW ') 1 for the small diameter portion 1
0 'may be configured to be moved as indicated by reciprocating arrows c' and d ', respectively.

The inventor has created a centerless grinding method and apparatus for stepped workpieces according to the invention of the prior application, and a centerless grinding apparatus for stepped workpieces according to the invention of the prior application. Practical application tests and research were continued, and it was confirmed that these inventions and inventions achieved the intended purposes, respectively, and that the following improvements were desired. For example, as shown in FIG. 7 (A), the stepped workpiece has a large diameter portion 1a and a small diameter portion 1b, and the two are connected by a conical surface 1c. When simultaneous grinding of the large diameter portion and the small diameter portion is performed by applying the invention of the prior application, the large diameter portion 1 is ground by the grinding wheel (G1) 7 for the large diameter portion.
a. Grinding wheel for small diameter part (G2)
8, the small diameter portion 1b and the conical surface 1c are ground. In this case, since the rotational speeds of the two grinding wheels 7 and 8 are controlled independently of each other, the rotational speeds of the two do not match. In particular, the grinding wheel (G1) 7 for the large diameter portion is rotationally driven and controlled so as to obtain an optimum peripheral speed for centerless grinding of the large diameter portion 1a, while the grinding wheel (G2) for the small diameter portion 8) is rotationally driven and controlled so as to obtain an optimum peripheral speed for the centerless grinding of the small diameter portion 1b, so that the rotational speeds of both grinding wheels are necessarily different. Therefore,
Both whetstones 7 and 8 cannot be brought into close contact with each other, and a slight gap must be provided. FIG. 7 (B) shows the state shown in FIG.
3 is an enlarged detailed view of a portion B of FIG. As shown in the drawing, a gap g must be provided between the large-diameter portion grinding wheel (G1) 7 and the small-diameter portion grinding wheel (G2) 8, so that an uncut portion 1d is formed. FIG. 7 has described the case where the conical surface 1c is provided between the large diameter portion 1a and the small diameter portion 1b. Such a case occurs, for example, when a drill material is centerlessly ground. That is, in the case of a straight shank, the shank of the drill corresponding to the large-diameter portion is configured to be, for example, 6 mm, 8 mm, and 10 mm in steps of 2 mm.
For the shank of each specified size, the drill cutting edge corresponding to the small diameter portion has 21 kinds of nominal diameters set in 0.5 mm increments, and the diameter difference between the shank and the drill cutting edge is connected by a conical surface. I have. Leaving the conical surface as black scale without grinding does not adversely affect the drilling function as a drill, but it is desirable to grind the conical surface because it reduces the commercial value. However, when the large diameter portion (shank) and the small diameter portion (drill cutting edge) are simultaneously ground using the centerless grinding device according to the invention of the earlier application or the invention of the earlier application, an attempt is made to grind the conical surface. Then, the uncut portion 1d described with reference to FIG. 7B is generated. FIG. 7 shows the case where the large diameter portion and the small diameter portion are connected by the normal conical surface 1c. However, when the apex angle of this conical surface becomes 180 ° as the maximum limit value, that is, the large diameter portion When the boundary between the small diameter portion 1a and the small diameter portion 1b is a step surface perpendicular to the axis, the same problem of uncut portion occurs. Since the rotation speeds of the large-diameter portion grinding wheel (G1) 7 and the small-diameter portion grinding wheel (G2) 8 are different from each other and cannot be brought into close contact with each other, the remaining grinding remains near the boundary between the large-diameter portion and the small-diameter portion. The occurrence of a part is an unavoidable problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a stepped workpiece is centered on a large-diameter portion grinding wheel and a small-diameter portion grinding wheel whose peripheral speeds are independently controlled. It is an object of the present invention to provide a centerless grinding method that does not generate an uncut portion in the vicinity of a stepped portion of a workpiece when performing less grinding.

[0006]

In order to achieve the above object (prevention of uncut portions), the centerless grinding method for stepped workpieces according to the present invention comprises a large-diameter cylindrical surface, a small-diameter cylindrical surface, A method of centerless grinding a stepped workpiece having a conical surface connecting a large-diameter cylindrical surface and a small-diameter cylindrical surface, comprising: a. While grinding the large-diameter cylindrical surface using a large-diameter portion grinding wheel whose peripheral speed is controlled independently,
After grinding the small-diameter cylindrical surface and conical surface with a small-diameter portion grinding wheel whose peripheral speed is controlled separately from the large-diameter portion grinding wheel, b. The boundary between the large-diameter cylindrical surface and the conical surface of the stepped workpiece while moving the stepped workpiece relative to the large-diameter portion grinding wheel toward the large-diameter cylindrical surface. It is characterized in that the vicinity is ground.

[0007]

According to the above method, the large diameter portion and the small diameter portion can be centerlessly ground at an appropriate peripheral speed with high accuracy in the step shown in item a. Is efficiently removed in the step b.
A stepped workpiece with no uncut portion is obtained.

[0008]

1A to 1E show an embodiment of a centerless grinding method according to the present invention. In this embodiment, the centerless grinding method of the present invention is applied to prevent the generation of uncut portions when grinding a drill material using the centerless grinding device according to the invention of the earlier application described with reference to FIG. It was done. In FIG. 1, the blades are omitted as in FIG. 4A. FIG. 1A shows a preparation process for a grinding operation, in which a workpiece 1 is inserted into an insertion arm 15.
Is pushed in the direction of arrow j and is inserted into a fixed position. The reference numeral 7 denotes a grinding wheel (G1) for a large-diameter portion, which faces an adjustment grinding wheel (RW) 9 for a large-diameter portion. Reference numeral 8 denotes a grinding wheel (G2) for the small diameter portion, which faces the shoe 10.
The shoe 10 is mounted on the same slide base (not shown) as the adjusting grindstone (RW) 9. FIG.
(B) is a state in which infeed grinding has been started by the grinding wheel (G1) 7 and the adjusting wheel (RW) 9 for the large diameter portion. The feed angle of the adjusting grindstone in the in-feed grinding is generally about 10 ′ to 20 ′, but in the present embodiment, the feed angle was set to about 1 °. This is to obtain a relatively large feed force in a step (E) described later. Book (B)
At the stage shown in the drawing, the workpiece 1 is supported by the insertion arm 15 with the feed force directed to the left in the drawing, and is stationary in the left-right direction. The large diameter part 1a is a large diameter part grinding wheel (G1) 7 and an adjusting wheel (RW).
9 and the grinding wheel (R
W) 9 is cut in the direction of arrow k. The shoe 10 installed on the same slide base as the adjusting grindstone (RW) 9 is fed in the direction of arrow k 'in parallel with the arrow k. When the grinding state of the large-diameter portion 1a is stabilized, the small-diameter portion grinding wheel (G2) 8 is cut in the direction of the arrow m as shown in FIG. 1C, and the centerless grinding of the small-diameter portion 1b supported by the shoe 10 is performed. Is started. At the time of grinding the small diameter portion 1b, the conical surface 1 is formed by the small diameter portion grinding wheel (G2) 8.
The grinding of c is also performed. As shown in FIG. 7C, the uncut portion 1d is formed while the centerless grinding of the large-diameter portion 1a, the small-diameter portion 1b, and the conical surface 1c proceeds. Then, as shown in FIG. (D), the grinding wheel (G2) 8 for the small diameter portion is moved to the arrow n.
And the insertion arm 15 is retracted in the direction of arrow q. The large-diameter portion 1a of the workpiece 1 has an adjustment grindstone
W) Since a feed force in the direction of arrow q 'is received at the feed angle of 9, the feed is passed in the same direction, and the uncut portion 1d is removed by through feed grinding. (E) shows a state in which the removal of the uncut portion has been completed.

As described above, in the present embodiment, the centerless grinding apparatus (FIG. 4) according to the invention of the prior application is used to prevent high precision centerless grinding by an appropriate peripheral speed, which is an advantage of the apparatus. It is possible to remove the uncut portion in the vicinity of the stepped portion without the need for additional mechanical devices. Although not shown, the centerless grinding method for stepped parts according to the present invention can be similarly applied to the centerless grinding apparatus (FIG. 6) according to the invention of the prior application, and the same effect (high Prevents uncut portions without hindering precision grinding). The embodiment shown in FIG.
And the small-diameter portion 1b are connected by a conical surface 1c, but the method of the present invention can be applied regardless of the apex angle of the conical surface. The extreme state in which the apex angle of the conical surface is the maximum is the apex angle of 180 °, which is a stepped surface perpendicular to the axis. FIG. 2 shows an example in which the method of the present invention is applied when a workpiece having a stepped surface perpendicular to the axis as described above is ground by the centerless grinding apparatus (FIG. 4) according to the prior application. It is typical process explanatory drawing. FIG. 2A shows a state in which infeed grinding of the large-diameter portion 1a of the workpiece 1 has been started by the large-diameter portion grinding wheel (G1) 7 and the adjusting wheel (RW) 9, and FIG. It is a schematic diagram corresponding to (B). Since the workpiece of the above embodiment was a material for drilling, the tip of the small diameter portion 1b was sharpened,
However, the workpiece of this embodiment (FIG. 2) is a simple stepped shaft, and the small diameter portion 1b does not have a back taper and the tip is not sharp. Grinding wheel for large diameter part (G1) 7, adjusting wheel (RW) 9, grinding wheel for small diameter part (G2) 8, shoe 1
0 and the insertion arm 15 are the same as those in the embodiment (FIG. 1). (A) When the grinding of the large-diameter portion 1a is started as shown in the figure and the state is stabilized, the small-diameter portion 1b of the workpiece as shown in the diagram (B)
While the shoe 10 is supported by the shoe 10 and the shoe 10 is fed in the direction of the arrow k ', the grinding wheel (G2) 8 for the small diameter portion is cut as shown by the arrow m to perform the centerless grinding of the small diameter portion 1b. The stepped surface 1e of the workpiece 1 is finished by grinding. When the small diameter portion 1b is ground to a predetermined diameter and the stepped surface 1e is ground and finished, the small diameter portion grinding wheel (G2) 8 is retracted in the direction of arrow n as shown in FIG. In this state, an uncut portion 1d is formed. Then, the insertion arm 15 is retracted in the direction of the arrow q, and the workpiece 1 is fed in the same direction by applying a feed force in the direction of the arrow q ', and the uncut portion 1d is removed by through feed grinding.
FIG. 2D shows a state where the uncut portion has been removed. As described above with reference to FIG. 2, the centerless grinding method for a stepped workpiece according to the present invention provides a method in which the apex angle of the conical surface connecting the large diameter portion and the small diameter portion of the stepped workpiece is the maximum. Value 1
The same applies to the case of 80 °.

[0010]

When the method according to the present invention is applied to centerless grinding of a stepped workpiece using a large-diameter portion grinding wheel and a small-diameter portion grinding wheel whose peripheral speeds are controlled independently of each other, Centerless grinding of the large diameter portion and the small diameter portion at the optimum peripheral speed, and no uncut portion near the stepped portion.

[Brief description of the drawings]

FIG. 1 is a process explanatory view showing one embodiment of a centerless grinding method for a stepped workpiece according to the present invention.

FIG. 2 is a process explanatory view showing an embodiment different from the above in the centerless grinding method according to the present invention.

FIG. 3 is a schematic drawing of two views showing an embodiment of a centerless grinding apparatus for stepped workpieces.

FIG. 4 is a two-sided view showing one embodiment of a centerless grinding apparatus for stepped workpieces according to the invention of the prior application.

FIG. 5 is a process chart showing one embodiment of a centerless grinding method for a stepped workpiece according to the invention of the prior application.

FIG. 6 is a two-sided view showing one embodiment of a centerless grinding apparatus for a stepped workpiece according to the invention of the prior application.

FIG. 7 is an explanatory diagram of a problem in the centerless grinding apparatus according to the invention of the prior application and the invention of the prior application.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Stepped workpiece, 1 '... Material of workpiece, 1a ... Large diameter part, 1b ... Small diameter part, 1c ... Conical surface, 1d ... Uncut part,
1e: stepped surface, 2 ... conventional grinding wheel, 3 ... conventional grinding wheel, 4 ... blade, 5, 6 ... drive mechanism, 7 ... first grinding wheel for large diameter portion, 8 ... small diameter portion A second grinding wheel,
9 ... adjustment grindstone for large diameter portion, 10 ... shoes, 10 '... adjustment grindstone for small diameter portion, 12a, 12b, 13, 14 ... drive mechanism, 15 ... insertion arm.

Claims (2)

(57) [Claims] A method for centerless grinding a stepped workpiece having a large-diameter cylindrical surface and a small-diameter cylindrical surface, and a conical surface connecting the large-diameter cylindrical surface and the small-diameter cylindrical surface, comprising: a. . Along with grinding the large-diameter cylindrical surface using a large-diameter portion grinding wheel whose peripheral speed is independently controlled, a small-diameter portion grinding wheel whose peripheral speed is controlled separately from the large-diameter portion grinding wheel After grinding the small diameter cylindrical and conical surfaces, b. The boundary between the large-diameter cylindrical surface and the conical surface of the stepped workpiece while moving the stepped workpiece relative to the large-diameter portion grinding wheel toward the large-diameter cylindrical surface. A centerless grinding method for stepped workpieces, characterized by grinding the vicinity. 2. The conical surface has a maximum apex angle of 180 degrees as the maximum limit, and the grinding with the grinding wheel for small diameter portion in the step b) is performed when grinding a small diameter cylindrical surface. 2. The method of claim 1, wherein the conical surface having a vertical angle of 180 degrees is simultaneously ground.