JPH0740209A - Grinding method of cylindrical work of centerless grinder and work holding device - Google Patents

Abstract

PURPOSE:To highly precisely and highly efficiently grind a cylindrical work by improving roundness and cocentricity at the time of grinding the cylindrical work the shaft center of which is held on both ends by a centerless grinder. CONSTITUTION:A work 28 is ground by holding both ends of the work 28 free to rotate at a position slightly heightening a shaft center higher than a line (a) connecting a center P of a grinding wheel 1 and a center Q of a regulating wheel 6 to each other and by releasing the work 28 diagonally downward at the time when grinding force of the grinding wheel 1 works. On a centerless grinder, an oscillating frame 23 supporting the both ends of the work 28 is provided, an oscillating fulcrum shaft 19 of this oscillating frame 23 is positioned at a position biased to the grinding wheel 1 below the work 28, and a line (b) connecting the shaft center of the work 28 and the shaft center of the oscillating fulcrum shaft 19 to each other at the time when the work 28 is made contact with the grinding wheel 1 is positioned and set so that the line (b) is inclined by about thirty degrees relative to a vertical line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for grinding a cylindrical work with a centerless grinding machine with an axis as a reference, and a work holding device used for carrying out the method.

[0002]

2. Description of the Related Art As is well known, a centerless grinder, as shown in FIG. 7, supports a grinding wheel 1, an adjusting wheel 6, and an upper surface of a work rest 42 at three points on the outer circumference of a work 28 while supporting the grinding wheel. 1 is a machine for rotating the work 1 and the adjusting wheel 6 to grind the outer circumference of the cylindrical work 28 on the basis of the outer circumference, and originally does not include a device for holding the axis of the work.

A cylindrical grinder is used to grind a workpiece with an axis as a reference. For example, when grinding the outer periphery 32 of the rotary support shaft of the small motor shown in FIG. 6, one end of the rotary support shaft is provided with a center hole 29, and a spline 33 cut with the center hole 29 as a reference, and a bearing surface 34, When grinding 34 and the outer circumference 36 of the rotor, the coaxiality with the spline 33 becomes a problem. Although such a work 28 can be processed with a centerless grinder much more efficiently than a cylindrical grinder, the spline 33 can be used.
After machining, the shaft is bent in the heat treatment and other steps during the final grinding step, and the coaxiality cannot be obtained in the normal centerless machining in which the outer circumference is ground. Therefore, the work 28 in which the coaxiality with the axis is a problem is actually processed by a cylindrical grinder, but it is not possible to simultaneously grind at a plurality of locations, and the work is supported only at the centers at both ends. Therefore, there is a problem that the work is inefficient because the work is distorted or chattered due to the grinding force and heavy grinding cannot be performed.

Therefore, it has been attempted to provide a centerless grinding machine with a device for holding both ends of the work and process the work 28 as described above by the centerless grinding machine. The grinding method is that the cylindrical work is supported rotatably at the shaft centers of both ends, and the middle part is sandwiched between the rotating grinding wheel and the adjusting wheel, and the downward direction is applied to the work by the rotation of the grinding wheel. The force (grinding force) is used to grind while holding the small-diameter shaft end portions protruding on both sides of the work into V grooves of a holding device described later.

As shown in FIG. 8, the work holding device used for carrying out this method has a structure in which both ends of the work 28 are axially supported by a center or V groove 37 which is provided so as to be movable back and forth in the axial direction of the work. In order to allow the movement of the shaft center of the work as the machining progresses, the swing frame 23 having the center and the V groove 37 at the upper end is provided at the lower part of the work and is a swing fulcrum shaft parallel to the shaft of the grinding wheel. The structure is supported by 19.

[0006]

However, when the conventional work holding device is used, the self-centering function of the centerless grinding machine is lost, and the roundness is reduced as compared with the case of machining with the cylindrical grinder. there were. That is, if such a work holding device is used, the coaxiality is improved as compared with the case where the centerless grinding machine is used without using such a work holding device, but the coaxiality is improved as compared with the case where the cylindrical grinding machine is used. Roundness will decrease.

[0007] Therefore, an object of the present invention is to obtain a technical means for further improving the roundness when grinding the cylindrical work by using the centerless grinding machine while holding the shaft centers of both ends of the work, Therefore, it is an object to make it possible to perform a work such as a rotation support shaft of a small motor with high accuracy and high efficiency while achieving coaxiality.

[0008]

A method of grinding a cylindrical work in a centerless grinding machine according to the present invention is a cylindrical work 2
In a method of grinding a cylindrical work in a centerless grinding machine, which rotatably supports 8 at both ends of the shaft center and grinds the intermediate part between the rotating grinding wheel 1 and the adjusting wheel 6 in a state of being ground. , The work 28 is brought into contact with the grinding wheel 1 at a position where the axis of the work 28 is slightly higher than the line a connecting the center P of the grinding wheel 1 and the center Q of the adjusting wheel 6, and the grinding force of the grinding wheel 1 is brought into contact. It is characterized by grinding the work 28 while allowing the work 28 to escape obliquely downward.

A work holding device for a centerless grinding machine according to the present invention includes a grinding wheel 1 and an adjusting wheel 6 which support a cylindrical work 28 rotatably at its both ends and rotate an intermediate portion thereof. In a work holding device of a centerless grinder that grinds in a state of being sandwiched between the two, the rocking fulcrum shaft 19 of the rocking frame 23 that supports both ends of the work 28 has the grinding wheel 1 below the work 28.
A line b connecting the axis of the work 28 and the axis of the swing fulcrum shaft 19 when the work 28 is brought into contact with the grinding wheel 1 is about 30 degrees with respect to the vertical line. The workpiece 28 is positioned so as to incline, and the workpiece 28 should come into contact with the grinding wheel 1 at a position where the axis is slightly higher than the line a connecting the center P of the grinding wheel 1 and the center Q of the adjusting wheel 6. It is characterized by.

[0010]

When the work holding device having the above construction holds the shafts at both ends of the work and grinds the work with the centerless grinding machine, the work center height is determined by the center of the grinding wheel 1 and the adjusting wheel 6 (P, Since it is slightly higher than Q), the grinding wheel 1 to the work 28
By the obliquely downward grinding force applied to the work, the work escapes obliquely downward and is pressed against the adjusting wheel 6, whereby the coaxiality of the work is improved as the grinding progresses. In the case of normal centerless grinding with three-point support on the outer periphery, as shown in FIG. 7, the work receiving surface of the work rest is tilted toward the adjusting wheel 6 side by about 30 degrees, and the work 28 is adjusted by the grinding force of the grinding wheel 1. 6
The work holding device according to the present invention has a work guiding action (automatic centering action) similar to the outer periphery-based centerless machining, and improves the machining accuracy.

[0011]

EXAMPLE A first example shown in FIGS. 1 and 2 will be described below. The grinding wheel 1 has a grinding wheel stand 3 fixed to a base 2.
It is pivotally supported by and rotates at a fixed position. On the upper surface of the base 2, there is provided an adjustment chassis 4 which is movable toward the grinding wheel 1.
An adjusting wheel 6 is pivotally supported on the adjusting wheel base 4 via an adjusting wheel frame 5 in which the angle of the rotation center axis can be adjusted slightly. The rotary drive mechanisms of the grinding wheel 1 and the adjusting wheel 6 and their dressing devices are omitted in the figure.

A first arm holder 9 is attached to the tip of the base 8 of the adjustment carriage 4 (the end on the grinding wheel side) so that the position of the first arm holder 9 can be adjusted slightly in the horizontal direction. The second arm holder 10 is attached so that its position can be adjusted slightly. The first arm holder 9 and the second arm holder 10 are slidably guided in horizontal and vertical directions by guide rails (not shown), and are screwed to the first bracket 11 fixed to the base 8. The first adjusting screw 12 and the second adjusting screw 14 screwed into the second bracket 13 fixed to the first arm holder 9 adjust the respective positions to fix the fixing screw 1
The second arm holder 10 is fastened by fastening with 5 and 16.
Are fixed in the desired horizontal and vertical positions.

Support brackets 18 are fixed to the second arm holder 10 at positions on both sides of the grinding wheel 1 so as to extend to the grinding wheel 1 side. Swing fulcrum shafts 19 extending to the front and back sides are planted. An arm 20 extending obliquely upward is pivotally supported on the swing fulcrum shaft 19, and two arms 20 located on the front side and the back side in the figure with the grinding wheel 1 sandwiched therebetween are fixedly integrated by a connecting member 21. . A stopper cylinder 22 having a rod directed upward is fixedly attached to the upper surface of the first arm holder 9 below the connecting member 21. The two arms 20 are connected and integrated by a connecting member 21 to form a swing frame 23 that swings around the swing fulcrum shaft 19.

A center 25 facing inward is fixed to one end of one of the two arms 20, and a similar center 26 is attached to the other end of the arm 20 so as to be movable back and forth in the axial direction. A cylinder 27 is attached. The centers 25 and 26 are cones having an apex angle of 60 degrees and are fitted into center holes 29, 29 bored in the shaft centers of both ends of the work 28 to hold the shaft center of the work 28. In this embodiment, the structure in which the center of the work is supported by the centers 25 and 26 so as to be freely rotatable is described.
It is also possible to have a structure in which the shaft end portion of the small diameter projecting to both sides of the work 28 is held by the bearing portion at the tip of the. Of course, when grinding the outer peripheral portion of the shaft end, it is necessary to have a structure in which the work is held by the centers 25 and 26 as in this embodiment. The bearing surfaces 34, 34 of the work 28 shown in FIG. 6 can be ground simultaneously by selecting the shape of the grindstone.

Next, the grinding operation in the apparatus of the above embodiment will be described. First, according to the size of the work to be ground, the first arm holder 9 and the second arm holder 9 on the base 8
When the position of the arm holder 10 is set and the work 28 is pressed against the grinding wheel 1 by the adjusting wheel 6, that is, the adjusting carriage 4
When the base 8 of is moved to the grinding wheel 1 side, the work 2
The shaft center of 8 (center of the centers 25, 26) is located slightly above the line a connecting the center P of the grinding wheel 1 and the center Q of the adjusting wheel 6, and the centers 25, 26 of the arms 20 The position of the swing fulcrum shaft 19 is set so that the line b connecting the shaft center and the shaft center of the swing fulcrum shaft 19 is approximately 60 degrees with respect to the line connecting the centers P and Q. At this time, the height of the stopper cylinder 22 is adjusted so that a slight gap is formed between the rod tip of the stopper cylinder 22 and the bottom surface of the connecting member 21.

In this state, the center escape cylinder 27
The center 26 is retracted to insert the work 28 from above between the grinding wheel 1 and the adjusting wheel 6, and the center 26 is advanced by the center escape cylinder 27, and the center holes 29 at both ends of the inserted work 28, 29 is supported by two centers 25 and 26 facing each other. Then, the adjusting wheel 6 is advanced to the grinding wheel 1 side, the outer periphery of the work 28 is pressed against the grinding wheel 1, and the peripheral surface of the work 28 is ground by the grinding wheel 1 while rotating the work 28 by the rotation of the adjusting wheel 6. To do.
At this time, as explained in the section of the above-mentioned action, the axis of the work 28 is slightly above the centers P and Q of the grinding wheel 1 and the adjusting wheel 6 and the cutting force of the grinding wheel 1 causes the work 2 to move.
A self-centering action is exerted by the synergistic action of pressing 8 on the adjusting wheel 6 so as to escape obliquely downward, and the outer periphery of the work 28 is ground so as to be coaxial with its axis.

When the grinding is completed, the adjusting wheel 6 is slightly retracted, the work 28 is separated from the grinding wheel 1, and the connecting member 21 of the rocking frame that descends while rocking is brought into contact with the rod tip of the stopper cylinder 22. By stopping the swing of the swing frame 23, the work 28 is separated from the adjusting wheel 6, and the robot hand is inserted from above to grip the work 28.
The center escape cylinder 27 retracts the center 26 to release the work, and the work 28 is taken out upward.

3 to 5 show a second embodiment of the present invention. In this embodiment, the swing support shaft 19 fixed to the arm 20 rotatably penetrates the support bracket 18 and extends toward the grinding wheel side, and the extending portions are connected integrally by a U-shaped connecting member 21. The oscillating frame 23 is formed by being liquefied. One of the swing support shafts 19 is extended to the side opposite to the grinding wheel, and a lever 30 is fixed to the tip thereof. Lever 3
A stopper cylinder 22 fixed to the first arm holder 9 is provided below the tip of 0. A work rest 42 is fixedly provided on the upper surface of the first arm holder 9 via a mounting bracket 41 between the grinding wheel 1 and the adjusting wheel 6. The upper surface of the work rest 42 is inclined in the direction in which the adjusting wheel 6 side is lowered at an angle of about 30 degrees, like the upper surface of the work rest of the conventional centerless grinding machine.

The grinding operation of this embodiment will be described with reference to FIG. The position of the swing fulcrum shaft 19 is set in the same manner as in the above-described embodiment. At this time, a slight gap is formed between the rod tip of the stopper cylinder 22 and the bottom surface of the lever 30 and between the work 28 and the top surface of the work rest 42. In this state, the work is inserted and both ends of the work are supported by the centers 25 and 26, and the outer periphery is ground based on the axial center as in the first embodiment (FIG. 5A). When the grinding based on the axial center is completed, the base 8 is retracted to open the centers 25 and 26, and the work 28 is placed on the work rest 42 (see FIG.
(B)), the base 8 is fed again to perform normal centerless processing (FIG. 5 (c)). By doing so, the support rigidity of the work is increased, heavy grinding is possible, and machining with a higher roundness than that of the first embodiment is possible.

[0020]

According to the method of the present invention described above, the concentricity between the grinding surface and the shaft center of the work when the outer circumference of the cylindrical work is held by the centerless grinding machine while holding the shaft centers at both ends thereof. Can be significantly improved compared to similar processing in the conventional centerless grinding machine, and it becomes possible to perform outer peripheral grinding based on the shaft center of a cylindrical work with high accuracy and high efficiency. There is. Further, the work holding device according to the present invention has an effect that the above method can be efficiently performed.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of the present invention.

FIG. 2 is a plan view of a main part showing a holding state of a work.

FIG. 3 is a side view showing a second embodiment of the present invention.

FIG. 4 is a front view showing the adjustment vehicle removed.

FIG. 5 is a side view of an essential part showing a grinding operation.

FIG. 6 is a front view showing an example of a cylindrical work.

FIG. 7 is a schematic side view of workpiece holding with reference to the outer periphery in centerless grinding.

FIG. 8 is a schematic side view of a conventional workpiece holding device with an axial center reference.

[Explanation of symbols]

 1 Grinding wheel 6 Adjusting wheel 19 Swing fulcrum shaft 23 Swing frame 28 Workpiece a Line connecting P and Q b Line connecting center 25 and swing fulcrum shaft 19

Claims (2)

[Claims] 1. A grinding wheel (1) which supports a cylindrical work (28) so as to be freely rotatable at the axial centers of both ends thereof and rotates an intermediate part thereof.
In the grinding method for cylindrical workpieces in a centerless grinder that grinds between the wheel and the adjusting wheel (6), the grinding wheel
Line (a) connecting the center (P) of (1) and the center (Q) of the adjustment vehicle (6)
The work (28) is brought into contact with the grinding wheel (1) at a position where the axis of the work (28) is slightly higher, and the work (28) is slanted when the grinding force of the grinding wheel (1) acts. A method for grinding a cylindrical work in a centerless grinding machine, characterized by grinding while letting it escape downward. 2. A grinding wheel that supports a cylindrical work (28) so as to be freely rotatable at the shaft centers of both ends thereof and rotates an intermediate portion thereof.
In the work holding device of a centerless grinding machine that grinds in a state of being sandwiched between (1) and the adjusting wheel (6), the rocking fulcrum shaft (() of the rocking frame (23) supporting both ends of the work (28) ( 19) is the position below the work (28) and is biased toward the grinding wheel (1).
The line (b) connecting the axis of the workpiece (28) and the axis of the swing fulcrum shaft (19) when the (28) is brought into contact with the grinding wheel (1) is approximately 30 degrees with respect to the vertical line. The workpiece (28) is positioned so as to be inclined, and the work (28) is centered on the grinding wheel (1) (P) and the adjustment wheel (6).
A work holding device for a centerless grinding machine, characterized in that it comes into contact with the grinding wheel (1) at a position where the axis is slightly higher than the line (a) connecting (Q).