JPH022670B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a dressing device for a grinding wheel for grinding a female thread groove, and more particularly to a device for dressing a grindstone for grinding a female thread groove using a dresser having a dressing surface on the outer surface. It is.

[Conventional technology]

In thread groove grinding of female threads, there is a method of grinding while maintaining a constant angular relationship in which the grindstone shaft is parallel or inclined to the axis of the threaded hole of the workpiece. In this method, a ring-shaped dresser is used as the dresser for the grinding wheel, which has a groove-shaped dressing surface on its inner periphery that is the same as that of the female thread to be ground, or a ring-shaped dresser that has a groove-like dress surface that is the same as that of the female thread. Ru. In the case of a female-threaded dresser, the axial position of the dresser is fixed, and the grindstone is shaped and dressed by providing relative screw feed (swivel and movement feed synchronized with rotation) and the required depth of cut to the grindstone and dresser.

[Problem that the invention seeks to solve]

The above-mentioned dresser has a dressing surface formed on its inner circumference, so when grinding a workpiece with a small screw hole diameter, the diameter of the dresser will also be smaller, so the number of diamond grains on the dressing surface will be reduced. , it may be difficult to create an accurate grindstone shape.

Furthermore, since the dressing surface of the dresser is defined according to the specifications of the thread groove to be ground, there is also the problem that different dressers must be manufactured for each of these specifications.

Therefore, it is an object of the present invention to solve the above problems by using a dresser provided with a dressing surface on the outer surface.

[Means for solving problems]

In order to solve the above problems, the configuration of the present invention is as follows.

On a virtual orthogonal coordinate having XYZ axes, the grindstone shaft 4 is attached to the rotating member 5 so as to have a constant angular relationship parallel to or inclined to the Z axis, and approximately the middle of the width of the grindstone 3 is positioned on the XY plane.

A dressing surface 7 having an appropriate cross-sectional shape of the female thread groove 2 to be ground is formed on the outer surface of the dresser 6.

The dresser 6 is attached to the support member 14 so that its dressing surface 7 has the same angular and positional relationship with the axis of the female screw hole of the cross section of the female thread groove from which the cross-sectional shape was obtained.

Either the rotating member 5 or the supporting member 14 is mounted to be swingable around the Z-axis, and a base is installed so that the rotating member 5 or the supporting member 14 can reciprocate in the Z-axis direction in synchronization with the swinging cycle. It is movably installed on top of 8.

Further, the positional relationship between the grindstone 3 and the dresser 6 is set so that the outer peripheral surface of the grindstone 3 and the dresser surface 7 can partially contact each other during the swinging motion.

[Effect]

In the device configured as described above, the swing radius of the support member 14 of the dresser 6 is set according to the thread groove hole diameter of the product (the thread groove bottom diameter after grinding, etc.), and the eccentricity ρ of the grinding wheel axis from the Z axis is adjusted. is appropriately set using a cutting feed device or the like to bring the dressing surface 7 into contact with the outer peripheral surface of the grindstone 3 at the origin, for example on the X axis, and the support member 14
When the support member 14 is reciprocated in the Z-axis direction in synchronization with the rocking, the envelope surface of the rocking locus of the dressing surface 7 draws the groove shape of the female thread 2 to be ground, and the envelope At a portion of the surface, the grinding wheel 3 and the dressing surface 7 are in contact, and shaping and dressing are performed.

Note that the above is a combination that gives the dresser 6 rocking around the Z-axis and reciprocating movement in the Z-axis direction.
As other combinations, the dresser 6 may be given the same rocking motion as described above, and the grindstone 3 may be given reciprocating movement, or the grindstone 3 may be given rocking motion and reciprocating motion.

[First Embodiment] FIG. 1 shows a ball screw nut 1 as an example of a workpiece to be ground. The lead angle θ of the female thread 2 of this nut 1, the lead is L, and the BCD (distance between ball centers) is D. 2 and 3 show the dressing device of the first embodiment. (In addition,
In the following description, in order to clarify the positional relationship of each member, the description will be made using orthogonal coordinates having XYZ axes as a reference. ) In the device of the first embodiment, the shaft 4 of the grinding wheel 3 is attached to a rotating member 5 such as a spindle on the X axis and parallel to the Z axis, and approximately the middle of the width of the grinding wheel 3 is located on the XY plane. The grindstone 3 is rotated.

The dresser 6 is disc-shaped and has a dressing surface 7 formed on its outer peripheral surface. The dressing surface 7 is formed by a groove having a cross-sectional shape in the direction perpendicular to the lead of the two female thread grooves, that is, a cross-sectional shape equal to the cross-sectional shape at the indicated line l of the lead angle θ in FIG. The profile when the grains are fixed is equal to the cross-sectional shape of the female thread groove).

The support device for the dresser 6 is constructed as follows.

That is, a support 10 is provided on the base 8 so as to be slidable in the X-axis direction via a slide mechanism 9, a first drive device 11 is mounted on the support 10, and its drive shaft 12 is positioned on the Z-axis. A rotary disk 13 is fixed to the drive shaft 12.

A support member 14 is integrally fixed to the front surface of the rotary disk 13, and the support member 14 swings together with the rotary disk 13 up and down about the X-axis within a required angle range of π/2 or less.

Further, the support member 14 is the center of swing (X axis)
A guide rail 15 parallel to the X-axis is provided on the front surface of the support member 14 when the support member 14 is located at
A slide member 16 is fitted onto the guide rail 15. The slide member 16 is provided with a rack 17 on its lower side, and is moved in the X-axis direction by meshing with a pinion 19 of a second drive device 18 attached to the rotary disk 13.

Further, a third drive device 21 is provided on the slide member 16 via an inclination angle setting device 20, and the rotation shaft 22 of the device has an inclination equal to the lead angle with respect to the Z axis in the YZ plane. It protrudes at an angle θ, and a dresser 6 is attached to its tip.

The operation of the above device will be explained with reference to FIGS. 4 and 5.

First, the dresser 6 is driven by the third drive device 21.
After setting the inclination angle θ of the rotating shaft 22 to be equal to the lead angle θ of the female screw 2, the support member 14 is aligned parallel to the XY plane, and the second drive device 18 is driven to swing the slide member 16. The predetermined turning radius of the dresser 6, that is, the envelope surface of the dressing surface 7 is set so as to match the thread groove specifications of the product. In this state, the first drive device 11 is driven to swing the rotary disk 13 up and down about the X-axis at a required swing angle of π/2 or less.

Further, the support column 10 is reciprocated in synchronization with the above-mentioned rocking motion. Further, the eccentricity ρ (see FIG. 4) of the rotating member 5 such as a spindle is adjusted by a cutting device (not shown), and the rotating member 5 is brought into contact with the outer circumferential surface of the grindstone 3.

Now, using the angle parameter t (-π/2≦t≦π/2) around the Z-axis taken on the XY plane, find the innermost point P of the groove bottom on the dressing surface 7 (the point closest to the Z-axis).
Expressing the position as P (X _P , Y _P , Z _P ) (see Figure 4), X _P = r cos t Y _P = r sin t Z _P = L/2π = t, where r is the innermost point P is the radius of rotation, and L is the lead of the female thread 2.

Also, if the center point of the grinding wheel 3 is expressed as Q (X _Q , Y _Q , Z _Q ), then X _Q = ρ Y _Q = Z _Q = o However, ρ is the distance from the origin to the center point Q, and This is the amount of eccentricity of 5.

As mentioned above, the dressing surface 7 has the same cross-sectional shape as the thread groove of the female thread 2 in the direction perpendicular to the lead, and the rotating shaft 22 of the dresser 6 is inclined by the lead angle θ with respect to the Z-axis. When the column 10 is reciprocated in synchronization with the swinging of the column 14, the innermost point P
The trajectory forms the envelope 23 of the dressing surface 7. The envelope 23 is a combination of the movements of the above-mentioned members and depicts the thread groove bottom line of the female thread 2.

Therefore, when the grinding wheel 3 is placed on the X-axis, the envelope 23
Using this as a standard, add the required depth of cut and dress surface 7.
When brought into contact with the female thread, the same conditions as in the case of dressing with a dresser having a thread groove-like dressing surface on the inner peripheral surface that is the same as that of the female thread to be ground are satisfied.

[Second Embodiment] In the first embodiment described above, the reciprocating movement of the dresser 6 in the Z-axis direction was realized by moving the dresser 6 relative to the grindstone 3, but in the case of the second embodiment, As shown in FIGS. 6 and 7, this is realized by moving the grindstone 3 relative to the dresser 6 in the Z-axis direction.

In other words, the position P of the innermost point P (X _P , Y _P , Z _P )
is expressed as X _P = r cos t Y _P = r sin t Z _P = o. Also, the center position Q of the grinding wheel 3 (X _Q ,
Y _Q , Z _Q ) is expressed as X _Q =ρ Y _Q =o Z _Q =-L/2πt.

In this case, as in the case of the first embodiment, the same thread groove as the female thread 2 is formed by the compound motion of rocking around the Z-axis and reciprocating movement in the Z-axis direction synchronized with this, and the grinding wheel 3 is dressed by the thread groove.

[Third Example] As can be easily inferred from the first and second examples described above, similar results can be obtained even if the dresser 6 is fixed in a fixed position and the whetstone 3 is given a spiral movement. be able to.

That is, in the third embodiment, the rotating member 5 of the grindstone shaft 4 is given a swinging motion around the Z-axis and a reciprocating motion in the Z-axis direction in synchronization with this. In this case, the position of the innermost point P of the dresser 6 is expressed as X _P =r Y _P =o Z _P =o. _Further , the position of the center point _{Q of} the grindstone 3 is expressed as:

In this case as well, the same thread groove as the female thread 2 is formed by the compound movement as in the first and second embodiments.

[Fourth Embodiment] In each of the above embodiments, a disk-shaped dresser, that is, a rotary dresser was used as the dresser 6, but the fourth embodiment is shown in FIGS. As shown, a dresser 6' is constituted by a full-form cutting tool, and a dressing surface 7' is formed on the tip end thereof.

If the dressing surface 7' has a cross-sectional shape in the direction perpendicular to the lead of two female thread grooves, it is set to be inclined by a lead angle θ with respect to the Y axis.

The dresser 6' is supported by a cutting tool holder 24, and the cutting tool holder 24 is mounted on the slide member 16. The configuration other than the above is the same as that of the first embodiment.

Further, the combination of the compound motion of the swinging motion around the Z-axis and the reciprocating motion in the Z-axis direction can be the same as in the second and third embodiments.

In any of the above embodiments, the cross-sectional shape of the dressing surface is not limited to the cross-sectional shape of the female thread groove in the direction perpendicular to the lead;
The envelope surface when the dresser is turned spirally must not cause unnecessary interference with the regular female thread groove shape, so select an appropriate cross-sectional shape within a range that does not cause interference, or Corrections must be made.

For example, in the case of the disc-shaped dresser used in the first to third embodiments, the rotation axis is set at an angle approximately perpendicular to the lead (for example, with respect to the direction perpendicular to the lead) with respect to the axis of the female threaded hole. By setting lead angles on both sides) and a certain distance, the above-mentioned interference is prevented, and the contact point (line) shape and dresser are set so that the original female thread groove and dresser come into contact without a gap. The surface shape is uniquely determined.

However, when a full-length bite-shaped dresser as in the fourth embodiment is used, since the dressing surface is thin, interference when the dresser is turned spirally is smaller than that of a disc-shaped dresser. Therefore, there is a large degree of freedom in selecting the cross-sectional position of the female thread groove.

〔effect〕

As described above, in this invention, the dressing surface is formed on the outer periphery of the dresser, so even if the diameter of the female thread to be ground becomes smaller, the dressing surface is formed on the inner periphery. Since the number of diamond grains that can be placed is large and the dresser is easy to manufacture, precise shaping and dressing can be performed.

In addition, the female thread lead right angle cross-sectional shape (groove R shape)
By preparing a dresser for each ball screw (for each ball size in the case of ball screws), it can be used even if the leads and BCDs are different.

[Brief explanation of drawings]

Fig. 1 is an axial sectional view showing an example of a female thread groove;
Figure 2 is a front view of the first embodiment, Figure 3 is a side view of the same as above, Figures 4 and 5 are principle diagrams of the first embodiment, and Figures 6 and 7 are of the second embodiment. principle diagram,
Figures 8 and 9 are principle diagrams of the third embodiment;
FIG. 0 is a front view of the fourth embodiment, FIG. 11 is a side view of the same, and FIG. 12 is a partially enlarged sectional view of the dresser. 3...Whetstone, 4...Whetstone shaft, 6,6'...Dresser,
7, 7'...dress surface, 8...base, 9...slide mechanism, 10...pillar, 11...first drive device, 13...turntable, 14...support member, 18...second drive device, 2
0... Tilt angle setting device, 21... Third drive device, 22
...rotation axis, 23...envelope, 24...bite holder.

Claims (1)

[Claims] 1. On a virtual orthogonal coordinate system having XYZ axes, a grindstone shaft is attached to a rotating member so as to be parallel to the Z axis or inclined at a certain angle, and approximately the middle of the grindstone shaft is
A dressing surface is formed on the outer surface of the dresser, which is positioned on a flat surface and has an appropriate cross-sectional shape of the female thread groove to be ground. Mounted on a support member so as to have the same angular and positional relationship with respect to the hole axis, and either the rotating member or the supporting member is mounted so as to be swingable around the Z-axis, and the rotating member or the supporting member is The grindstone is movably installed on a base so that it can reciprocate in the Z-axis direction in synchronization with the above-mentioned oscillation cycle, and the positional relationship between the grindstone and dresser is such that the outer peripheral surface of the grindstone and the dressing surface are partially separated during the oscillation. A dressing device for a grinding wheel for grinding a female thread groove, which is configured so that it can come into contact with the grinding wheel. 2. The dressing surface of the dresser is formed to have a cross-sectional shape in the direction perpendicular to the lead of the female thread groove, and the dresser is mounted on a support member such that the dressing surface has an inclination equal to the lead angle of the female thread with respect to the Z axis. A dressing device for a grindstone for grinding a female thread groove according to claim 1. 3. Claim 1, wherein the dresser is disc-shaped and has a dressing surface formed on its outer peripheral surface.
A dressing device for a grindstone for grinding a female thread groove according to item 1 or 2. 4. The dressing device for a grindstone for grinding a female thread groove according to claim 1 or 2, wherein the dresser is a full-form cutting tool, and a dressing surface is formed on the tip end surface of the dresser.