JP2006198734A - Grinding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding method capable of preventing deterioration of machining accuracy due to the generation of grinding invalid component of a cutting force. <P>SOLUTION: In the grinding method, two workpieces 7, 7 parallelly disposed each other are ground in a noncircular shape by relatively moving the workpieces 7, 7 and a grinding wheel 5 on the plane orthogonal to the axis center O. Respective workpieces 7, 7 are made to be moved relative to the grinding wheel 5 along the line L connecting the axis center O of both workpieces. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a grinding method for non-circular workpieces such as camshafts and crankshafts.

As a grinding method for this kind of work, it is general to relatively move the work and the rotating grindstone on a surface orthogonal to the axis of the work while the work is held and rotated by a clamping device. However, since this method grinds one workpiece with one rotating grindstone, the processing efficiency is not good. Therefore, as shown in FIG. 5, two works a and b are arranged in parallel to each other, and the rotary grindstone e is divided into two perpendicular halves of a line segment c connecting the axis O of the works a and b. A method of moving along the line d has been proposed (see Patent Document 1).
JP-A-5-337806 (FIG. 6)

  However, according to this method, the component contributing to the grinding of the workpiece a out of the cutting force f of the rotary grindstone e with respect to the workpiece a is a component force in the direction from the contact point P of both to the center o of the workpiece a (hereinafter referred to as “a”). , Which is referred to as an effective grinding component) f1, and a component force f2 in the tangential direction T (hereinafter referred to as an ineffective grinding component) f2 does not contribute to the grinding of the workpiece a at all. When the grinding ineffective component f2 is increased, the rotating grindstone e vibrates, which causes a deterioration in processing accuracy.

  Further, the workpiece a is ground in the same rotational direction as the rotation of the rotating grindstone e (hereinafter referred to as upcut), and the workpiece b is ground in the direction opposite to the rotation of the rotating grindstone e (hereinafter referred to as downcut). As can be seen, the down-cut workpiece b has a smaller grinding resistance against the rotating wheel e of the workpiece b than the up-cut workpiece a, and there is a difference in the grinding resistance between the workpieces a and b. It is difficult to process as well.

  In view of such circumstances, an object of the present invention is to provide a grinding method capable of preventing deterioration of processing accuracy due to generation of a grinding ineffective component of a cutting force.

  In order to achieve the above object, the present invention provides a grinding method for grinding a plurality of workpieces arranged parallel to each other to a non-round shape by relatively moving the workpiece and a rotary grinding tool on a surface orthogonal to the axis of the workpiece. The relative movement between the workpiece and the rotary grinding tool is performed along a line connecting the axial centers of the two.

  According to such a configuration, since each workpiece is ground in contact with the rotary grinding tool on the line connecting both axes, the cutting force of the rotary grinding tool with respect to the workpiece becomes an effective grinding component. Ineffective components are not generated, and the vibration of the rotary grinding tool can be prevented.

  It is preferable to change the relative peripheral speed between the workpiece and the rotary grinding tool in accordance with the grinding phase of the workpiece while keeping the grinding phase of the workpieces the same.

  According to such a configuration, since the relative peripheral speed of each workpiece with respect to the rotary grinding tool is the same, when setting the relative peripheral speed of each workpiece to the optimum value, it is not necessary to match the workpiece with the slower relative peripheral speed, Reduction in processing efficiency can be prevented.

  It is preferable to equally arrange the workpieces in the circumferential direction of the rotary grinding tool.

  According to such a configuration, the resultant vector of the reaction force of the cutting force with respect to each workpiece becomes zero, and the bearing load of the rotary grinding tool is reduced.

  According to the present invention, when a plurality of workpieces are simultaneously ground with one rotary grinding tool, all of the cutting force of the rotary grinding tool with respect to the workpiece becomes a grinding effective component, and no grinding invalid component is generated. The occurrence of vibration of the tool is eliminated, and deterioration of machining accuracy can be prevented.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a view for explaining a grinding method of the present invention, and FIG. 2 is a plan view of a grinding apparatus for carrying out this method.

  In FIG. 2, reference numeral 1 denotes a base, and a pair of slide tables 2 are installed on the base 1 so as to be movable in the arrow X direction. A guide rail 3 is fixed between the slide tables 2 and 2 at the center of the base 1. On the guide rail 3, a grindstone table 4 is installed so as to be movable in a rotation axis direction Z perpendicular to the movement direction X of the slide table 2. The grindstone table 4 includes a grindstone 5 as a rotary grinding tool. Each slide table 2, 2 is provided with a clamp device 6, which is configured to hold a work 7 with this device 6 and to rotate it with a motor 8.

  In this grinding apparatus, the workpieces 7 and 7 are simultaneously ground while being in contact with the circumferentially bisected portion of the grindstone 5 (see FIG. 1). That is, the workpieces 7 and 7 move on a plane orthogonal to the axis O and move along a line L connecting the grindstone 5 and the axis O of the workpiece 7. Further, the workpieces 7 and 7 rotate in the same direction while maintaining the same grinding phase. Here, the grinding phase refers to the azimuth angle of the contact point of the workpiece 7 with respect to the grindstone 5 as viewed from the axis O when the apex P of the workpiece 7 and the point Po located on the opposite side of the axis O are used as a reference. I mean.

  FIG. 3 is a view showing a profile of a work 7 as a camshaft. The camshaft 7 includes a base circle portion 7a serving as a shaft and a lift portion 7b for lifting up a valve of the internal combustion engine. The vertex 7b is the vertex P of the camshaft 7. Now, assuming that the point Po located on the opposite side across the vertex P and the axis O is a grinding phase of 0 degrees and the vertex P is a grinding phase of 180 degrees, the clamping device 6 holding the workpiece 7 is a motor that rotates. 8, the workpiece 7 is rotationally driven at a rotational speed that changes in accordance with the axial azimuth (grinding phase) of the contact point of the work 7 with respect to the grindstone 5. When the rotational speed of the workpiece 7 when the grinding phase is 0 degree is 100 (relative value), the rotational speed of the workpiece 7 is about 50 (relative value), for example, in the vicinity of the lift portion, particularly at the apex P (grinding phase 180 degrees). ) Is known to be dropped. The motor 8 senses the grinding phase with a workpiece rotation control device (not shown) and is controlled so as to have a rotational speed corresponding to the grinding phase.

  Incidentally, since the work 7 and the grindstone 5 have only to be relatively moved on a surface orthogonal to the axis O of the work 7, the diameter of the grindstone 5 may be changed as shown in FIG. . Here, the grindstone 5 includes a main body portion 5a and a movable portion 5b, and the movable portion 5b is reciprocated along the radial direction by an actuator (moving means) 100. If it does in this way, the movement mechanism which makes the workpiece | work 7 approach / separate with respect to the grindstone 5 will become unnecessary, and compactization will be attained by abbreviate | omitting a pair of slide table 2. FIG.

  When the workpieces 7 and 7 are simultaneously ground, the workpieces 7 and 7 can be moved in the direction of the arrow X in FIG. 2 so that the workpieces 7 and 7 are repeatedly moved toward and away from the grindstone 5 while rotating the grindstone 5 and the workpieces 7 and 7. The slide table (contact mechanism) 2 is moved. The moving position of the slide table 2 is sensed by a control device that controls the movement of a contact mechanism (not shown), and the amount of movement is controlled. That is, the workpieces 7 and 7 are ground into a non-round shape by changing the movement amount according to the grinding phase.

  At that time, since the workpieces 7 and 7 are ground in a state where they are in contact with the grindstone 5 on a line L connecting both the axes O, the cutting force f of the grindstone 5 to the workpiece 7 is all effective grinding components. Thus, an ineffective grinding component is generated. For this reason, generation | occurrence | production of the vibration of the grindstone 5 is lose | eliminated, and deterioration of a processing precision can be prevented.

  By the way, in order to improve the processing accuracy, it is preferable to set the relative peripheral speed of the grindstone 5 and the workpiece 7 to an optimum value corresponding to the grinding phase of the workpiece 7 as described above. Therefore, the relative peripheral speeds of the workpieces 7 and 7 with respect to the grindstone 5 are made the same by rotating the workpieces 7 and 7 in the same direction as the rotation direction of the grindstone 5 while maintaining the same grinding phase. . Only the up-cut is performed without the down-cut described above, and the difference in grinding resistance between the workpieces 7 and 7 with respect to the grindstone 5 may be eliminated.

  In a conventionally known grinding apparatus, for example, a double-headed grinding machine as shown in Japanese Patent Application Laid-Open No. 2001-315048, two grinding wheel platforms are provided on one side of a workpiece, and a cam with one grinding wheel is provided. When grinding the cam profile, the other wheel simultaneously grinds the cam profile of the other cam. For example, a camshaft used in a 4-cylinder DOHC internal combustion engine will grind the profile of a total of 8 cams. In this case, since the cams in the same cylinder have a small arrangement pitch, if the above-mentioned double-head grinding machine is used for grinding, the cams in different cylinders must be ground, and the grinding phase cannot be made the same.

  For this reason, when setting the relative peripheral speed of the workpiece to the optimum value, it is necessary to match the profile of the cam having the slower relative peripheral speed, and it is not possible to expect an improvement in machining efficiency corresponding to the number of grindstones. It is known that when the number of grindstones is 2, the machining efficiency is 1.2 to 1.4 times. On the other hand, in this embodiment, since the relative peripheral speeds of the workpieces 7 and 7 with respect to the grindstone 5 are the same, it is not necessary to match the relative peripheral speed to the work 7 having the slower relative peripheral speed, and machining is performed. A reduction in efficiency can be prevented. That is, the machining capability can be improved in proportion to the number of clamping devices 6 that hold the workpiece 7. However, since it is only necessary to dispose the clamping device 6 on both sides of the grindstone 5, the installation space does not have to be increased.

  The pair of clamping devices 6 and 6 are provided on the independent slide tables 2 and 2, respectively, and the axis azimuth of the contact point of the workpieces 7 and 7 with respect to the grindstone 5 by the independent motors 8 and 8 ( The workpieces 7 and 7 may be of different types and can be processed flexibly.

  In addition, since the two workpieces 7 and 7 are equally divided in the circumferential direction of the grindstone 5, the resultant vector of the reaction force of the cutting force f with respect to each workpiece 7 and 7 becomes zero, and the bearing of the grindstone 5 The load can be reduced. When the number of workpieces 7 is three, the workpieces 7 may be arranged in three equal parts in the circumferential direction with respect to the grindstone 5 as shown in FIG. In addition, when it is not necessary to consider the bearing load of the grindstone 5 very much, it is not necessary to arrange | position the workpiece | work 7 equally as shown in FIG.

The figure explaining the grinding method of this invention. The top view of the apparatus which enforces the grinding method of this invention. The figure which shows the profile of a cam. The figure which shows the modification of FIG. The figure which shows the modification of FIG. The figure which shows the modification of FIG. The figure explaining the conventional grinding method.

Explanation of symbols

2 Slide table 3 Guide rail 4 Grinding wheel base 5 Grinding wheel 6 Clamping device 7 Work f Cutting force L wire O Shaft core P Contact

Claims (3)

  In a grinding method in which a plurality of workpieces arranged parallel to each other are ground to a non-round shape by relatively moving the workpiece and the rotary grinding tool on a surface orthogonal to the axis of the workpiece, the relative relationship between the workpiece and the rotary grinding tool is A grinding method characterized in that the movement is performed along a line connecting the axial centers of the two.   2. The grinding method according to claim 1, wherein the relative peripheral speed between the workpiece and the rotary grinding tool is changed in accordance with the grinding phase of the workpiece while the grinding phase of each workpiece is kept the same.   The grinding method according to claim 1 or 2, wherein the work is equally arranged in a circumferential direction of the rotary grinding tool.

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