JP3306485B2 - Grinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding machine for grinding a work such as a valve cam for an engine, and more particularly to an NC controlled grinding machine.

[0002]

2. Description of the Related Art Conventionally, this type of grinding machine is disclosed in
As can be seen in Japanese Patent Application Publication No. 109970, a grinding wheel spindle head having a disk-shaped grinding wheel mounted thereon slides a grinding wheel spindle head on a work supporting unit for supporting a work and a slide table which is advanced and retracted toward the work supporting unit. A grinding wheel support unit mounted so as to face in a direction perpendicular to the direction in which the table advances and retreats, and the slide table is advanced and retracted by a drive source under NC control via a ball screw mechanism to grind the workpiece. In this, the grindstone spindle head is mounted on the slide table with the grindstone projecting to one side of the slide table.

[0003]

In the above-mentioned conventional grinder, the reaction force of the grinding wheel causes the slide table to move to the slide table.
A tilting moment acts to tilt this in the direction perpendicular to the direction of its movement, and the followability of the slide table with respect to the NC control deteriorates, making it difficult to improve the machining accuracy. In view of the above points, an object of the present invention is to provide a grinding machine with improved followability of a slide table to NC control.

[0004]

In order to achieve the above object,
The present invention provides a work supporting unit that supports a work, and a whetstone spindle head having a disk-shaped whetstone mounted on a slide table that is moved forward and backward toward the work support unit. A grindstone supporting unit mounted so as to face in a direction perpendicular to the work table, and a work supporting unit for the slide table in a grinding machine for grinding the work by moving the slide table forward and backward by NC control via a ball screw mechanism by a driving source. On the side end that slopes forward and downward toward the work support unit.
And an undercut portion at the front end of the mounting surface.
And the housing of the grinding wheel spindle head
A jaw that engages the undercut and the work support unit
Mounting that protrudes in the opposite direction to the mounting surface and sits on the mounting surface
A base is formed, and a grindstone spindle head is smelled between the jaw and the mounting base in a positional relationship such that the axial center position of the grindstone substantially matches the axis of the ball screw mechanism in plan view.
And fixed to the slide table .

[0005]

[Action] The line of action of the grinding reaction force from the grinding wheel does not offset with respect to the axis of the ball screw mechanism in the direction perpendicular to the direction in which the slide table advances and retreats. Therefore, the grinding reaction force acts on the slide table in the tilting moment in the orthogonal direction. Since the slide table can be received by the ball screw mechanism without doing so, the followability of the slide table to the NC control is improved. Further, if the mounting base of the housing is fixed to the mounting surface inclined forward and downward as described above, the grindstone spindle head will be attached to the slide table in the forward and downward inclined posture, and the arrangement height of the grindstone can be reduced. it can. As a result, the vertical distance between the line of action of the grinding reaction force and the axis of the ball screw mechanism is reduced, and the vertical tilting moment acting on the slide table 12 due to the grinding reaction force is reduced.
The followability of the slide table to the control is further improved. In addition, how
By engaging the jaws of the jig, the whetstone spindle head is
Can be prevented reliably.

[0006]

In the illustrated embodiment, the present invention is applied to an NC grinding machine for grinding a valve cam W for an engine, which is a work. As shown in FIG. 1, the NC grinding machine includes a front work support unit 2 and a rear grindstone support unit 3 provided on a 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 moved left and right by a drive source 4a such as a motor via a ball screw mechanism 4b with a space in the left and right direction. The valve cam W is set between the work spindle head 5 and the tail stock 6, and one end thereof is chucked by a chuck 5a at the tip of a spindle provided in the work spindle head 5, and is operated by the spindle motor 5b. The cam piece Wa is ground while rotating the valve cam W. In the figure, 7 is provided on the slide table 4,
This is a work rest that supports the journal of the valve gear W.

As shown in FIGS. 2 and 3, the grindstone support unit 3 is driven by 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, 9 on the base 8. A slide table 12 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 through the spindle.

The slide table 12 has an upper slider 12a which slidably engages the guide rails 9, 9 from the upper surface to the lateral inner surface, and the guide rails 9, 9.
A lower slider 12b slidably engaged with the lower surface of the guide rail 9 allows the guide rails 9, 9 to be movable back and forth in a state in which the left and right and vertical play are prevented. Then, a nut 11a containing a ball is fixed in the upper slider 12a, and a screw 11b connected to the drive source 10 is screwed into the nut 11a to form a ball screw mechanism 11. The slide table 12 is moved forward and backward by NC control of the drive source 10 in synchronization with the cam piece Wa.
Is ground to the required profile.

As shown in FIG. 4, the grindstone spindle head 15 includes a housing 16 and a spindle 17 supported by the housing 16. Then, the axial center position of the grinding wheel 18 connecting the grinding wheel spindle head 15 to the spindle 17 is aligned with the axis 11 of the ball screw mechanism 11 in plan view.
The bolt 19 was fixed to the front end of the slide table 12 in the housing 16 so as to conform to c. According to this, the action line of the grinding reaction force is the axis 1 of the ball screw mechanism 11.
1c, the grinding reaction force can be received by the ball screw mechanism 11 without applying a lateral tilting moment to the slide table 12, and N
The ability of the slide table 12 to follow the C control can be improved.

The housing 16 is integrally formed with a mounting base 16a projecting rearward. The mounting base 16a is seated on a mounting surface 12c formed on one lateral side of the front end of the slide table 12, and bolts 19 are formed. Stop it,
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 with the height of the grindstone 18 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 reduced, and the vertical tilting moment acting on the slide table 12 due to the grinding reaction force is reduced. , The followability of the slide table 12 with respect to the NC control is further improved.
The housing 16 is formed with a jaw 16b which is engaged with the undercut portion 12d at the front end of the mounting surface 12c and is fixed to the bolt 19 so that the whetstone spindle head 15 can be reliably prevented from floating. did. In the figure, reference numeral 20 denotes a grindstone cover attached to the housing 16 of the grindstone spindle head 15.

When the grindstone 18 is arranged within the width of the slide table 12 as in the present embodiment, when the grindstone diameter increases, the grindstone 1 at the front end of the slide table 12 becomes smaller.
8, it is necessary to cut out a large portion to prevent interference, and as a result, the support rigidity of the grindstone spindle head 15 attached to the front end of the slide table 12 is reduced, and it is difficult to improve the processing accuracy. become.

Further, it is necessary to retreat the grindstone 18 when the transition from the grinding of the base circle portion of the cam piece Wa to the grinding of the cam top portion is performed. In the case where the large-diameter grindstone 18 shown in FIG. The retreat amount Lb when the small-diameter grindstone 18 shown in FIG. 5B is used is smaller than the retreat amount La.
When the rotational acceleration of the valve operating cam W is constant, the retreating acceleration of the grindstone 18 at the time of transition from the base circle portion to the cam top portion is as shown in FIG.
In the case of a line and a small-diameter grindstone, the line is as shown by the line b in the same drawing. Therefore, as the grindstone diameter is reduced, the rotation speed of the valve cam W can be increased, and the processing time can be reduced.

Further, when a small diameter grindstone is used, a cam piece Wa having a concave profile depressed inward as shown in FIG.
Can also be ground, which increases the degree of freedom in designing the cam profile of the valve cam W.

As described above, there are various advantages when the grindstone diameter is reduced. However, in order to grind the valve operating cam W, the housing diameter of the grinding wheel spindle head 15 is adjusted so that the housing 16 does not interfere with the valve operating cam W. Must be smaller than the grindstone diameter. When the diameter of the housing 16 is reduced, the diameter of the spindle 17 supported by the housing 16 must be reduced. If the grindstone 18 is mounted in a cantilevered state on the portion of the spindle 17 protruding from the housing 16, the support of the grindstone 18 is not achieved. Rigidity cannot be secured.

Therefore, in the present embodiment, a cylindrical support portion 21 for loosely inserting the spindle 17 is provided at the end of the housing 16 on the side of the grindstone 18, and the support portion 21 has an axially spaced outer periphery. A pair of bearings 22, 22 were juxtaposed, and a cylindrical grindstone holder 23 was axially supported on the support portion 21 via the two 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 projecting from the support part 21 via a flange 25 bolted to the tip of the holder 23, and rotates integrally with the spindle 17. The flange 25 is fixedly fastened to the spindle 17 via a screw-type clamp member 25a.

The spindle 17 is provided at both ends of a portion around which the belt 14 is wound around a pair of first and second cylindrical portions 16c and 16d provided in the housing 16 at a distance in the axial direction via bearings 26, respectively. It is pivoted. In this embodiment, the first
An inner sleeve 16e is fixedly fitted inside 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.
The two bearings 22, 22 are preloaded in the axial direction by an adjuster 28 screwed into the inner periphery of the inner sleeve 16e via a disc spring 29 and a push rod 30.
The grindstone holder 23 can be axially supported without play in the radial and thrust directions.

According to the above configuration, even if the diameter of the housing 16 is reduced and the diameter of the spindle 17 is reduced, the grindstone 18 is supported by the support portion 21 via the grindstone holder 23 and the bearings 22 and 22. Therefore, the support rigidity of the grindstone 18 can be secured. As a result, the grindstone 18 having a small diameter can be used, and the diameter of the housing 16 and the spindle 17 can be reduced to reduce the weight of the grindstone spindle head 15 and the load on the slide table 12 can be reduced. Followability is improved, and machining accuracy is improved.

When the spring constants of the supporting portions of the bearings 22 and 22 are equal to each other, the amount of displacement of the grinding wheel 18 in the radial direction due to the grinding reaction force is set at the center of the span between the bearings 22 and 22. When the center position in the axial direction is matched, the minimum is obtained. However, 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 set. Double bearing 22,22
The amount of displacement is smaller when offset to one bearing 22 side than the center of the span between them. In this embodiment, since the support portion 21 is a cantilever, the spring constant of the support portion of the bearing 22 near the housing 16 is larger than the spring constant of the support portion of the bearing 22 on the distal end side. The grindstone 18 is externally fitted and fixed to the grindstone holder 23 in a state where the axial center position is offset toward the housing 16 from the center of the span between the two bearings 22, 22, and the grindstone 1 is formed by the grinding reaction force.
8 was minimized to further improve the processing accuracy.

Incidentally, lubricating oil air is supplied to each of the bearings 22 and 26 via an air supply passage 31 respectively. 3 in the figure
Reference numeral 2 denotes an air exhaust passage, and reference numeral 33 denotes a labyrinth structure seal ring for sealing the bearings 22 and 26 against outside air.

[0021]

As is apparent from the above description, according to the present invention, the tilting moment acting on the slide table due to the grinding reaction force can be reduced, and the followability of the slide table to the NC control can be improved. The workpiece can be ground with high precision.

[Brief description of the drawings]

FIG. 1 is a plan view of an example of a grinding machine having a grindstone spindle head according to the present invention.

FIG. 2 is a partially cutaway side view of a grinding wheel support unit of a grinding machine.

FIG. 3 is a front view cut along the line III-III of FIG. 2;

FIG. 4 is a cutaway front view of a grinding wheel spindle head.

FIGS. 5A, 5B, and 5C are diagrams showing a moving amount and an acceleration of a grindstone.

FIG. 6 shows a cam profile.

[Explanation of symbols]

2 Work Support Unit 3 Grindstone Support Unit 10 Drive Source 11 Ball Screw Mechanism 12 Slide Table 12c Mounting Surface 15 Grindstone Spindle Head 16 Housing 16a Mounting Base 18 Grindstone

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-56374 (JP, A) JP-A-4-201065 (JP, A) JP-A-63-109970 (JP, A) 30096 (JP, A) Japanese Utility Model Showa 60-175559 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B24B 5/04 B24B 19/12 B24B 41/04

Claims (1)

(57) [Claims] 1. A whetstone spindle head having a disk-shaped whetstone mounted on a work support unit that supports a work and a slide table that advances and retreats toward the work support unit. A grindstone supporting unit mounted so as to face in a direction perpendicular to the workpiece. The work table of the slide table is supported by a grinding machine that advances and retreats the slide table by NC control using a drive source via a ball screw mechanism to grind the work. At the end on the unit side , inclined forward and downward toward the work support unit
Mounting surface and an undercut portion at the front end of the mounting surface.
Forming and grinding wheel spindle head housing
A jaw engaged with the undercut portion;
Protrudes in the opposite direction to the holding unit and sits on the mounting surface
A grinding wheel spindle head and the mounting base in a positional relationship such that the axial center position of the grinding wheel substantially matches the axis of the ball screw mechanism in plan view.
A grinding machine characterized in that the grinding machine is fixed to a slide table .