JPH0911123A - Grinding wheel spindle head - Google Patents

Abstract

PURPOSE: To miniaturize the diameter of a housing of a grinding wheel spindle head without losing support rigidity of the grinding wheel. CONSTITUTION: A cylindrical support part 21 for loosely inserting a spindle 17 is provided in the tip part of a housing 16 for journalling the spindle 17. A cylindrical grinding wheel holder 23 to be coupled with the spindle is journalled around the outer circumference of the support part 21 via a bearing 22 and the grinding wheel 18 is externally fitted around the holder 23. Miniaturization of the diameter of the housing 16 miniaturizes the diameter of the spindle, however, the grinding wheel 18 is supported by the support part 21 so that support rigidity of the grinding wheel is not lost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grindstone spindle for mounting a disk-shaped grindstone, and more particularly to a grindstone spindle head suitable for an NC grinder.

[0002]

2. Description of the Related Art Conventionally, in a spindle head of this type, a spindle is axially supported by a housing, and a grindstone is externally fitted and fixed to the tip of the spindle protruding from the housing (see Japanese Utility Model Laid-Open No. 62-153037). ).

[0003]

By the way, in the NC grinder, the grindstone spindle head is mounted on the slide table which is controlled to move back and forth on the workpiece side. To improve the machining accuracy, the grindstone spindle head is made lighter. , N
It is desired to improve the followability of the slide table for C control.

In this case, it is necessary to reduce the diameter of the housing and the spindle. In the conventional grindstone spindle head, however, the grindstone is mounted in a cantilever state at the tip of the spindle protruding from the housing, so that the supporting rigidity of the grindstone is secured. However, the diameter of the spindle is limited, and the housing that supports the spindle cannot be made smaller toward the left, making it difficult to reduce the weight of the grindstone spindle head.

Further, when the engine valve cam is ground, the processing time can be shortened by reducing the diameter of the grindstone. In this case, it is necessary to make the housing diameter smaller than the grindstone diameter so that the housing of the grindstone spindle head does not interfere with the valve cam that is the work. Since it cannot be made so small, the diameter of the grindstone cannot be made smaller to the left.

In view of the above points, an object of the present invention is to provide a grindstone spindle head in which the supporting rigidity of the grindstone is ensured and the diameters of the housing and the spindle can be reduced.

[0007]

In order to achieve the above object,
The present invention, in a grindstone spindle device for mounting a disk-shaped grindstone, is provided with a cylindrical support part for loosely inserting the spindle at the tip of a housing that pivotally supports the spindle, and a cylinder is provided around the outer periphery of the support part via a bearing. -Shaped grindstone holder is pivotally supported, and the grindstone holder is connected to the tip of a spindle protruding toward the tip of the support part so as to rotate integrally with the spindle, and the grindstone is externally fitted and fixed to the grindstone holder. And In this case, the bearings are arranged in a pair on the outer circumference of the support portion with a gap in the axial direction, and the axial center position of the grindstone is offset toward the housing side from the center of the span between the bearings. It is preferable that the grindstone is fitted and fixed to the grindstone holder in this state.

[0008]

Since the grindstone is supported by the cylindrical support portion at the tip of the housing via the grindstone holder, it is possible to secure the supporting rigidity of the grindstone even if the diameter of the spindle is reduced. Therefore, the spindle can be downsized and the housing can be downsized. If a pair of bearings are arranged side by side as described above, the grindstone holders are supported at both ends by the support portion, the support rigidity of the grindstone holder is increased, and further, the grindstones are offset to the housing side, whereby grinding is performed. The bending moment acting on the support portion by the reaction force is reduced, and the support rigidity of the grindstone is further improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the illustrated embodiment, the present invention is applied to an NC grinder that grinds a valve operating cam W for an engine, which is a work. As shown in FIG. 1, the NC grinder includes a work support unit 2 on the front side and a grindstone support unit 3 on the rear side, which are provided on the machine base 1. The work supporting unit 2 has a work spindle head 5 and a tail stock 6 mounted on a slide table 4 which is horizontally moved by a drive source 4a such as a motor via a ball screw mechanism 4b with a space left and right. The valve cam W is set between the work spindle head 5 and the tail stock 6, one end of which is chucked by the chuck 5a at the tip of the spindle provided in the work spindle head 5, and is driven by the spindle motor 5b. While rotating the valve cam W, the cam piece Wa is ground. In the figure, 7 is provided on the slide table 4,
It is a work rest that supports the journal portion of the valve operating cam W.

As shown in FIGS. 2 and 3, the grindstone support unit 3 drives a motor or the like along a base 8 fixed to the machine base 1 and a pair of left and right guide rails 9 on the base 8. A slide table 12 that is moved back and forth by a source 10 via a ball screw mechanism 11, a spindle motor 13 mounted on the slide table 12, and a belt 14 by a spindle motor 13 attached to the front end of the table 12.
And a grindstone spindle head 15 having a spindle driven via.

The slide table 12 includes an upper slider 12a slidably engaged with the guide rails 9 and 9 from the upper surface to the inner side surface in the lateral direction, and the guide rails 9 and 9.
By the lower slider 12b slidably engaged with the lower surface of the above, the guide rails 9 and 9 are supported by the guide rails 9 and 9 so as to be able to move back and forth while preventing back and forth play. Then, a nut 11a containing a ball is fixed in the upper slider 12a, and a screw rod 11b connected to the drive source 10 is screwed into the nut 11a to form a ball screw mechanism 11 for rotating the valve operating cam W. The slide table 12 is moved back and forth by NC control of the drive source 10 in synchronism with the cam piece Wa.
To the required profile.

As shown in FIG. 4, the grindstone spindle head 15 comprises a housing 16 and a spindle 17 pivotally supported by the housing 16. The axial center position of the grindstone 18 connecting the grindstone spindle head 15 to the spindle 17 is the axis 11 of the ball screw mechanism 11 in plan view.
A bolt 19 was fastened to the front end of the slide table 12 in the housing 16 so as to match c. According to this, the line of action of the grinding reaction force is the axis line 1 of the ball screw mechanism 11.
1c is not laterally offset, and the grinding reaction force can be received by the ball screw mechanism 11 without applying a lateral tilting moment to the slide table 12.
The followability of the slide table 12 with respect to the C control can be improved.

The housing 16 is integrally formed with a mounting base 16a projecting rearward, and the mounting base 16a is seated on a mounting surface 12c formed at one lateral side of the front end of the slide table 12 to attach the bolt 19 to the mounting surface 16c. Stop,
In this embodiment, the mounting surface 12c is inclined forward and downward so that the grindstone spindle head 15 can be mounted on the slide table 12 in a state where the height of the grindstone 18 is lowered as much as possible. According to this, the vertical distance between the line of action of the grinding reaction force and the axis 11c of the ball screw mechanism 11 is shortened, and the vertical tilting moment acting on the slide table 12 by the grinding reaction force is reduced. , NC control of the slide table 12 is further improved.
The housing 16 is provided with a jaw portion 16b which is engaged with the undercut portion 12d at the front end of the mounting surface 12c and fixed with the bolt 19 so that the whetstone spindle head 15 can be reliably prevented from rising. did. Reference numeral 20 in the drawing denotes a grindstone cover attached to the housing 16 of the grindstone spindle head 15.

By the way, when the grindstone 18 is arranged within the lateral width of the slide table 12 as in this embodiment, when the grindstone diameter becomes large, the grindstone 1 at the front end portion of the slide table 12 becomes large.
It is necessary to make a large notch in the portion corresponding to 8 to prevent interference, and as a result, the supporting rigidity of the grindstone spindle head 15 attached to the front end portion of the slide table 12 is reduced, making it difficult to improve machining accuracy. become.

Further, it is necessary to retreat the grindstone 18 at the time of shifting from the grinding of the base circular portion of the cam piece Wa to the grinding of the cam top portion. When the large-diameter grinding stone 18 shown in FIG. 5A is used. 5B, the retreat amount Lb is smaller when the small-diameter grindstone 18 shown in FIG. 5B is used.
Then, when the rotational acceleration of the valve operating cam W is constant, the backward acceleration of the grindstone 18 at the time of shifting from the base circle portion to the cam top portion is a in FIG.
Lines and small-diameter grindstones are as shown by line b in the figure, and when a small-diameter grindstone is used, it is not necessary to retreat due to sudden acceleration unlike large-diameter grindstones. Therefore, the smaller the diameter of the grindstone, the higher the rotational speed of the valve operating cam W, and the shorter the processing time.

Further, when a small-diameter grindstone is used, a cam piece Wa having an inwardly concave concave profile as shown in FIG.
Also, the degree of freedom in designing the cam profile of the valve operating cam W is increased.

As described above, reducing the diameter of the grindstone has various advantages. However, in order to grind the valve cam W, the diameter of the housing 16 of the grindstone spindle head 15 should be adjusted so as not to interfere with the valve cam W. Must be less than the diameter of the grindstone. When the diameter of the housing 16 is reduced, the diameter of the spindle 17 that supports it must be reduced. If the grindstone 18 is attached to the portion of the spindle 17 protruding from the housing 16 in a cantilever state, the grindstone 18 cannot be supported. The rigidity cannot be secured.

Therefore, in this embodiment, a cylindrical support portion 21 into which the spindle 17 is loosely inserted is provided at the end of the housing 16 on the side of the grindstone 18, and there is an axial interval on the outer circumference of the support portion 21. A pair of bearings 22, 22 were arranged side by side, a cylindrical grindstone holder 23 was pivotally supported by the support portion 21 via the bearings 22, 22, and the grindstone 18 was externally fitted and fixed to the holder 23. The grindstone holder 23 is connected to the tip of the spindle 17 protruding from the support portion 21 via a flange 25 bolted to the tip of the holder 23 and rotates integrally with the spindle 17. The flange 25 is fastened and fixed to the spindle 17 via a screw type clamp member 25a.

The spindle 17 is provided with bearings 26 on a pair of first and second cylindrical portions 16c and 16d, which are axially separated from each other on the housing 16 at both ends of the winding portion of the belt 14. It is pivotally supported. In this embodiment, the first
An inner sleeve 16e is fitted and fixed to the cylindrical portion 16c, and the support portion 21 is integrally formed with the sleeve 16e.

A spacer 27 is provided between the bearings 22 and 22.
Is interposed, and both bearings 22, 22 are pre-loaded in the axial direction via a disc spring 29 and a push rod 30 by an adjuster 28 screwed into the inner circumference of the inner sleeve 16e,
The grindstone holder 23 can be pivotally supported in the radial direction and the thrust direction without play.

According to the above structure, even if the spindle 17 is reduced in diameter by reducing the diameter of the housing 16, the grindstone 18 is axially supported by the support portion 21 via the grindstone holder 23 and the bearings 22 and 22. Therefore, the supporting rigidity of the grindstone 18 can be secured. As a result, a grindstone 18 having a small diameter can be used, and the grindstone spindle head 15 can be made lighter by reducing the diameters of the housing 16 and the spindle 17, and the load on the slide table 12 can be reduced, so that the slide table 12 for NC control can be reduced. Followability is improved and processing accuracy is improved.

By the way, when the spring constants of the supporting portions of both the bearings 22 and 22 are equal to each other, the radial displacement of the grindstone 18 due to the grinding reaction force is such that the grindstone 18 is located at the center of the span between the both bearings 22 and 22. It becomes the smallest when the axial center positions are matched, but when the spring constant of the support portion of one bearing 22 is larger than the spring constant of the support portion of the other bearing 22, the axial center position of the grindstone 18 is Both bearings 22, 22
The amount of displacement is smaller when the bearing 22 is offset toward the one bearing 22 side than the center of the span. In the present embodiment, since the support portion 21 is a cantilever, the spring constant of the supporting portion of the bearing 22 near the housing 16 is larger than the spring constant of the supporting portion of the bearing 22 on the tip side, so that the whetstone 18 The grindstone 18 is externally fitted and fixed to the grindstone holder 23 in a state where the axial center position is offset to the housing 16 side with respect to the span center between both bearings 22 and 22, and the grindstone 1 by the grinding reaction force 1
The displacement of No. 8 was suppressed to the minimum, and the processing accuracy could be further improved.

Oils for lubrication are supplied to the bearings 22 and 26 through the air supply passage 31, respectively. 3 in the figure
Reference numeral 2 is an air exhaust passage, and 33 is a seal ring having a labyrinth structure for sealing the bearings 22 and 26 against the outside air.

[0024]

As is apparent from the above description, according to the present invention, it is possible to secure the supporting rigidity of the grindstone even if the diameter of the spindle is reduced, and it is possible to reduce the diameter of the housing. As a result, it is possible to reduce the weight of the grindstone spindle head, improve the followability to NC control, reduce the diameter of the grindstone to improve the efficiency of the grinding work, and further increase the degree of freedom in designing the work shape.

[Brief description of the drawings]

FIG. 1 is a plan view of an example of a grinder including a grindstone spindle head according to the present invention.

[Fig. 2] Side view of a partial cutting of a grindstone support unit of a grinder

FIG. 3 is a front view taken along the line III-III of FIG.

FIG. 4 is a cutaway front view of the grindstone spindle head.

5 (a), (b) and (c) are diagrams showing the movement amount and acceleration of the grindstone.

FIG. 6 is a diagram showing a cam profile.

[Explanation of symbols]

 15 Grindstone Spindle Head 16 Housing 17 Spindle 18 Grindstone 21 Support Part 22 Bearing 23 Grindstone Holder

Claims (2)

[Claims] 1. A grindstone spindle device for mounting a disk-shaped grindstone, wherein a cylindrical support portion for loosely inserting the spindle is provided at a tip end portion of a housing that pivotally supports the spindle, and a bearing is provided on the outer periphery of the support portion. While supporting the cylindrical grindstone holder axially, the grindstone holder is connected to the tip of a spindle protruding toward the tip of the support portion so as to rotate integrally with the spindle, and the grindstone is externally fitted and fixed to the grindstone holder. Characteristic grindstone spindle head. 2. A pair of the bearings are arranged side by side on the outer periphery of the support portion with an interval in the axial direction, and the axial center position of the grindstone is offset toward the housing side from the center of the span between the bearings. The grindstone spindle head according to claim 1, wherein the grindstone is externally fitted and fixed to the grindstone holder in the state in which the grindstone is held.