An aspect of the present invention relates to a grinding wheel truing method and a grinding machine adopting the truing method.
Conventionally, works of various shapes are processed on a grinding machine. For example, as shown in
The above-described grinding wheel TA is a so-called angular grinding wheel TA where, as shown in
Here, when the conical surface WC of the work W is ground, between a conical surface WC1 on the side close to the work rotation axis ZW and a conical surface WC2 on the side far from the work rotation axis ZW, the circumferential speed is higher on the side far from the work rotation axis ZW. Consequently, the difference in diameter on the conical surface WC of the work W causes a difference in grinding removal amount, which causes a difference in the finished surface roughness of the finished work.
Moreover, the angular grinding wheel TA, which has a shape where the grinding surface TA1 is inclined with respect to the grinding wheel rotation axis ZTA, has a large-diameter portion TA3 where the diameter of the outer periphery is relatively large and a small-diameter portion TA2 where it is small. For this reason, on the grinding surface TA1 of the angular grinding wheel TA, the number of abrasive grains arranged in the circumferential direction of the large-diameter portion TA3 tends to be relatively larger than the number of abrasive grains arranged in the circumferential direction of the small-diameter portion TA2. Therefore, resulting from the fact that the small-diameter portion TA2 of the grinding surface TA1 of the angular grinding wheel TA processes the work W with a small number of abrasive grains compared with the large-diameter portion TA3, the finished surface roughness of the work W having undergone the processing tends to be large.
Here, in the grinding of the conical surface WC of the work W by the angular grinding wheel TA, a relationship occurs such that the large-diameter portion TA3 of the angular grinding wheel TA contacts the conical surface WC1 on the side close to the work rotation axis ZW and the small-diameter portion TA2 of the angular grinding wheel TA contacts the conical surface WC2 on the side far from the work rotation axis ZW. For this reason, the finished surface roughness of the finished conical surface WC of the work W is larger on the conical surface WC2 on the side far from the work rotation axis ZW due to a combination of the influence accompanying the difference in the circumferential speed of the work W and the influence accompanying the difference in the number of abrasive grains of the angular grinding wheel TA.
Here, the technique described in Patent Document 1 uses a grinding wheel that has a grinding surface smaller than the width of the conical surface of the work, and the grinding wheel contacting the conical surface is moved along the generating line of the conical surface to perform grinding. In this grinding, the finished surface roughness of the finished conical surface is attempt to fall within a desired tolerance by changing the rotation speed of the work.
Patent Document 1: JP-A-2004-345054
However, according to the technique in Patent Document 1, processing of the conical surface takes time, so that processing cannot be performed efficiently. Accordingly, the inventors of the present application focus attention on a method for truing a grinding wheel by a truer that performs truing and dressing of a grinding wheel.
An aspect of the present invention has been made in view of such a point, and a problem to be solved is to reduce, when a conical surface of a work is ground, the difference in finished surface roughness between the conical surface on the side close to the work rotation axis and the conical surface on the side far from the work rotation axis, and process the work more efficiently.
To solve the above-mentioned problem, the present invention includes a grinding wheel truing method and a grinding machine according the following aspects.
First, a first aspect of the present invention includes a grinding wheel truing method, in a grinding machine which comprises a grinding wheel having an axial length on an outer peripheral surface of the grinding wheel substantially equal to a length of a generating line of a conical surface of a work, and which grinds the conical surface of the work by bringing the outer peripheral surface into contact with the conical surface without relatively moving the grinding wheel in a direction of the generating line of the conical surface, for truing the grinding wheel using a truer, the grinding wheel for grinding the conical surface of the work by bringing the outer peripheral surface of the grinding wheel of the grinding machine into contact with the conical surface while rotating the work having the conical surface about the work rotation axis with respect to the work rotation axis, wherein, when the outer peripheral surface of the grinding wheel is trued while a position of the truer with respect to the grinding wheel is relatively moved along the outer peripheral surface of the grinding wheel from one end side toward the other end side in an axial direction of the grinding wheel on the outer peripheral surface of the grinding wheel, a relative movement speed of the truer when a position of the outer peripheral surface of the grinding wheel which grinds a large-diameter portion of the conical surface of the work is trued is lower than a relative movement speed of the truer when a position of the outer peripheral surface of the grinding wheel which grinds a small-diameter portion of the conical surface of the work is trued.
According to this first aspect, by changing the relative movement speed of the truer in performing truing, the surface condition of the grinding wheel can be changed. That is, the grinding surface roughness of the grinding surface of the grinding wheel that grinds the conical surface on the side far from the work rotation axis where the circumferential speed is high is made relatively smaller than the grinding surface roughness of the grinding surface of the grinding wheel that grinds the conical surface on the side close to the work rotation axis where the circumferential speed is low. Thereby, when the conical surface of the work is ground, the difference in finished surface roughness can be made smaller between the conical surface on the side close to the work rotation axis and the conical surface on the side far from the work rotation axis. Moreover, by making the axial length of the grinding wheel on the outer peripheral surface of the grinding wheel substantially equal to the length of the generating line of the conical surface of the work, when the outer peripheral surface of the grinding wheel is brought into contact with the conical surface and is ground, the grinding can be performed without relatively moving the grinding wheel in the direction of the generating line of the conical surface, so that the work can be processed efficiently. Therefore, when the conical surface of the work is ground, the difference in finished surface roughness can be made smaller between the conical surface on the side close to the work rotation axis and the conical surface on the side far from the work rotation axis, and the work can be processed more efficiently.
A second aspect of the present invention includes the rotary grindstone truing method according to the above-described first aspect, wherein the truer is relatively moved from the position of the outer peripheral surface of the grinding wheel which grinds the small-diameter portion of the conical surface of the work toward the position of the outer peripheral surface of the grinding wheel that grinds the large-diameter portion of the conical surface of the work, and the relative movement speed of the truer is gradually decreased, or wherein the truer is relatively moved from the position of the outer peripheral surface of the grinding wheel which grinds the large-diameter portion of the conical surface of the work toward the position of the outer peripheral surface of the grinding wheel that grinds the small-diameter portion of the conical surface of the work and the relative movement speed of the truer is gradually increased.
According to this second aspect, by gradually changing the relative movement speed of the truer in performing truing, the grinding surface roughness of the grinding wheel is gradually changed, so that the finished surface roughness of the conical surface of the work can be made more uniform.
A third aspect of the present invention includes the grinding wheel truing method according to the above-described first aspect or second aspect, wherein the grinding wheel is a cylindrical plane grinding wheel.
According to this third aspect, by the grinding wheel being the cylindrical plane grinding wheel, the difference in the number of abrasive grains arranged in the circumferential direction of the outer peripheral surface does not readily occur. For this reason, it is unnecessary to consider the difference in the density of the abrasive grains, and by adjusting the grinding surface roughness of the grinding surface of the grinding wheel, the finished surface roughness of the conical surface of the work can be adjusted, so that the finished surface roughness of the conical surface of the work can be made more uniform.
A fourth aspect of the present invention includes a grinding machine including: a grinding wheel; a truer that trues the grinding wheel; and control means, wherein the grinding machine carries out the grinding wheel truing method according to any one of the first aspect to the third aspect based on an instruction of the control means.
According to this fourth aspect, when the conical surface of the work is ground, a grinding machine can be obtained in which the difference in finished surface roughness can be made smaller between the conical surface on the side close to the work rotation axis and the conical surface on the side far from the work rotation axis and the work can be processed more efficiently.
According to aspects of the present invention, when the conical surface of the work is ground, the difference in finished surface roughness can be made smaller between the conical surface on the side close to the work rotation axis and the conical surface on the side far from the work rotation axis and the work can be processed more efficiently.
a) to 8(c) are graphs showing changes of the relative movement speed of a truer in performing truing in the present embodiment,
Hereinafter, an embodiment the present invention will be described by using the drawings. In the drawings, the x-axis, the y-axis and the z-axis are orthogonal to one another, the y-axis indicates a vertically upward direction, the z-axis indicates the direction of the work rotation axis ZW which is the rotation axis of the work W, and x-axis indicates the reciprocating direction of a turning platform 12.
Next, using
<General Structure of the Grinding Machine 1 (FIG. 1)>
As shown in
The main spindle table 11 reciprocates in the z-axis direction by a z-axis drive motor 11 M and a feed screw, and the control means outputs a control signal to the z-axis drive motor 11M while detecting a signal from position detection means 11E such as an encoder, thereby performing positioning of the main spindle table 11 in the z-axis direction.
The turning platform 12 reciprocates in the x-axis direction by an x-axis drive motor 12M and a feed screw, and the control means outputs a control signal to the x-axis drive motor 12M while detecting a signal from position detection means 12E such as an encoder, thereby performing positioning of the turning platform 12 in the x-axis direction.
On the main spindle table 11, a main spindle platform 20 provided with a center member 21 and a tailstock 30 provided with a center member 31 are placed, and the center member 21 and the center member 31 are disposed on the work rotation axis ZW parallel to the z-axis direction. Moreover, on the tailstock 30, a truing device 25 for truing the plane grinding wheel TP is placed. (Depending on the arranged position relationship of the plane grinding wheel TP, the truing device 25 may provided on the main spindle platform 20.)
The center member 21 is provided on a main spindle 22, the main spindle 22 is provided with a non-illustrated drive motor, and the control means is capable of rotating the main spindle 22 about the work rotation axis ZW passing through the tip of the center member 21, up to a given angle at a given angular speed.
The center member 31 is provided on a tail spindle 32, and the tail spindle 32 is supported rotatably or unrotatably.
The turning platform 12 is in the form of a plate in order that it is smaller in size, and in the neighborhood of the center of the turning platform 12, a turning motor 13 is provided in such a manner as to protrude in the y-axis direction. The control means outputs a control signal to the turning motor 13 while detecting a signal from angle detection means such as an encoder, thereby controlling the turning angle of the turning platform 12.
On the turning platform 12, a plane grinding wheel device 50 provided with the plane grinding wheel TP (corresponding to the grinding wheel) is disposed in such a manner as to sandwich the turning motor 13.
A grinding wheel rotation axis ZTP which is the rotation axis of the plane grinding wheel TP is situated within a plane orthogonal to the turning axis ZS.
The plane grinding wheel TP is attached to an end portion in one direction in the direction of the grinding wheel rotation axis ZTP (in
Moreover, the plane grinding wheel TP is rotated through a belt 50B from a grinding wheel drive motor 50M.
Moreover, although on the grinding machine 1, a coolant nozzle that supplies a coolant is provided in the neighborhood of the position of contact between the work W and the plane grinding wheel TP (the point of grinding), this is not illustrated.
As shown in
In the plane grinding wheel TP, the axial length of the grinding surface TP1 which is the outer peripheral surface thereof is substantially equal to the length of the generating line WL (see
As shown in
Although not shown, the work rotation axis ZW, the grinding wheel rotation axis ZTP and a truer rotation axis ZTR of the truing device 25 are disposed on a relatively moving plane orthogonal to the turning axis ZS.
<General Structure of the Work W (FIG. 2)>
As shown in
As shown in
<Structure of the Truing Device 25 (
As shown in
The truing device 25 has a truer TR rotated about the truer rotation axis ZTR parallel to the work rotation axis ZW and a non-illustrated drive motor that rotates this truer TR.
Here, as a piece of knowledge of the grinding wheel of the grinding machine, there is a correlation between the grinding allowance cross-sectional area and the finished surface roughness of the ground processed surface of the work (the work W in the present embodiment). That is, there is a relationship such that the larger the grinding allowance cross-sectional area is, the larger (rougher) the finished surface roughness of the processed surface of the work is.
Moreover, as a piece of knowledge about truing of the grinding wheel of the grinding machine, there is a relationship such that the higher the movement speed of the truer with respect to the grinding wheel is, the larger the finished surface roughness of the processed surface of the work processed by the grinding wheel trued by the truer.
Based on these pieces of knowledge, in the truing of the plane grinding wheel TP, attention is focused on changing the speed of the truer TR.
<Processing Procedure of the Method for Truing the Plane Grinding Wheel TP (FIG. 7)>
Next, using the flowchart shown in
At step S10, the control means relatively turns and moves the position of the truer TR with respect to the plane grinding wheel TP (the position shown in
At step S20, the control means sets the initial movement speed of the relative movement speed F of the truer TR with respect to the plane grinding wheel TP, and proceeds to step S30. For example, when the truing start position A shown in
At step S30, the control means moves the relative position of the truer TR with respect to the plane grinding wheel TP at the set relative movement speed F to perform truing (the condition shown in
At step S40, the control means detects the current relative position of the truer TR with respect to the plane grinding wheel TP, and proceeds to step S50.
At step S50, the control means determines whether the relative position of the truer TR with respect to the plane grinding wheel TP has reached a truing end position B (see
When proceeding to step S60, the control means sets the movement speed according to the position, returns to step S30, and repeats step S30 and succeeding steps. For example, when movement is being made from the side where the small-diameter portion WBi of the conical surface WC of the work W is ground to the side where the large-diameter portion WBo is ground, the movement speed is decreased gradually or in steps according to the position (see
When proceeding to step S70, the control means turns or moves the position of the plane grinding wheel TP to the initial position (the position shown in
The change in the relative speed of the plane grinding wheel TP and the truing device 25 is made gradually or in steps. Here, although it is more desirable that the change in the relative speed F of the plane grinding wheel TP and the truing device 25 be changed successively according to the relative position of the truer TR with respect to the plane grinding wheel TP as shown in
By performing the above-described truing, the grinding surface TP1 of the plane grinding wheel TP is brought into a condition where the protrusion amount of the abrasive grains gradually changes as shown in
Regarding the protrusion amount H of the abrasive grains TP2 on the grinding surface TP1, truing is performed so that as shown in
As described above, according to the method for truing the plane grinding wheel TP (grinding wheel) and the grinding machine 1 for carrying out the truing method according to the present embodiment, by changing the relative movement speed of the truer TR in performing truing, the surface condition of the plane grinding wheel TP can be changed. That is, the grinding surface roughness of the grinding surface TP1 of the plane grinding wheel TP that grinds the conical surface WC in the position on the side far from the work rotation axis ZW where the circumferential speed is high (the side of the large-diameter portion WBo) is made relatively smaller than the grinding surface roughness of the grinding surface TP1 of the plane grinding wheel TP that grinds the conical surface WC in the position on the side close to the work rotation axis ZW where the circumferential speed is low (the side of the small-diameter portion WBi). By doing this, when the conical surface WC of the work W is ground, the difference in finished surface roughness can be made smaller between the position of the conical surface WC on the side close to the work rotation axis ZW (the side of the small-diameter portion WBi) and the position of the conical surface WC on the side far from the work rotation axis ZW (the side of the large-diameter portion WBo). Moreover, by making the axial length of the plane grinding wheel TP on the grinding surface TP1 (corresponding to the outer peripheral surface of the grinding wheel) of the plane grinding wheel TP substantially equal to the length of the generating line WL of the conical surface WC of the work W, when the conical surface WC is ground by bring the outer peripheral surface of the plane grinding wheel TP into contact with the conical surface WC, the conical surface WC can be ground without relatively moving the plane grinding wheel TP in the direction of the generating line WL of the conical surface WC, so that the work W can be processed efficiently.
Moreover, by gradually changing the relative movement speed of the truer TR in performing truing, the grinding surface roughness of the plane grinding wheel TP is gradually changed, so that the finished surface roughness of the conical surface WC of the work W can be made more uniform.
Moreover, by the grinding wheel being the cylindrical plane grinding wheel TP, the difference in the number of abrasive grains arranged in the circumferential direction of the grinding surface TP1 does not readily occur. For this reason, it is unnecessary to consider the difference in the density of the abrasive grains TP2, and by adjusting the grinding surface roughness of the grinding surface TP1 of the plane grinding wheel TP, the finished surface roughness of the conical surface WC of the work W can be adjusted, so that the finished surface roughness of the conical surface WC of the work W can be made more uniform.
Moreover, the grinding machine 1 can be obtained where when the conical surface WC of the work W is ground, the difference in finished surface roughness can be made smaller between the position of the conical surface WC on the side close to the work rotation axis ZW (the side of the small-diameter portion WBi) and the position of the conical surface WC on the side far from the work rotation axis ZW (the side of the large-diameter portion WBo) and the work W can be processed more efficiently.
While the embodiment of the present invention is described above, the grinding wheel truing method and the grinding machine for carrying out the truing method of the present invention is not limited to the present embodiment, and may also be carried out in various forms without departing from the scope of the invention.
For example, while in the present embodiment, the grinding wheel truing method is described with the plane grinding wheel TP as an example, the present invention is also applicable in the case of an angular grinding wheel.
Moreover, while an example where in the x-axis direction, the plane grinding wheel TP is movable with respect to the work W and in the z-axis direction, the work W is movable with respect to the plane grinding wheel TP is shown in the present embodiment, the structure is only necessarily such that the plane grinding wheel TP is relatively movable in the x-axis direction and in the z-axis direction (movable on the xz plane [corresponding to the relatively moving plane]) with respect to the work W.
Moreover, while regarding the grinding machine 1 described in the present embodiment, an example where the plane grinding wheel TP is provided on the turning platform 12 is shown, the present invention is not limited thereto, and a multifunction grinding machine where a plane grinding wheel and an angular grinding wheel are disposed in appropriate positions on the turning platform may be adopted. According to this, various portion other than the conical surface of a work can be ground.
While regarding the grinding machine 1 described in the present embodiment, an example where each grinding wheel is supported in a cantilever manner is shown, the grinding wheel may be supported in a double support manner.
The shape and structure of the grinding wheel and the shape of the work W are not limited to the ones described in the present embodiment.
The present application is based upon Japanese Patent Application (No. 2013-073593) filed on Mar. 29, 2013, the contents of which are incorporated herein by reference.
1: Grinding Machine
10: Base
11: Main Spindle Table
12: Turning Platform
13: Turning Motor
11M: Z-axis Drive Motor
11E: Position Detection Means
12M: X-axis Drive Motor
12E: Position Detection Means
20: Main Spindle Platform
21: Center Member
22: Main Spindle
25: Truing Device
30: Tailstock
31: Center Member
32: Tail Spindle
50: Plane Grinding Wheel Device
50B: Belt
TP: Plane Grinding Wheel (Grinding Wheel)
TP1: Grinding Surface (Outer Peripheral Surface of Grinding Wheel)
TP2: Abrasive Grain
H: Protrusion Amount
HA: Protrusion Amount
HB: Protrusion Amount
W: Work
WC: Conical Surface
WA: Spindle Portion
WB: Disc-shaped Portion
WBi: Small-Diameter Portion
WBo: Large-Diameter Portion
WC: Conical Surface
Di: Diameter
Do: Diameter
WL: Generating Line
Wθ: Angle
ZS: Turning Axis
ZW: Work Rotation Axis
ZTP: Grinding Wheel Rotation Axis
ZTR: Truer Rotation Axis
TR: Truer
TR1: Truer Surface
F: Relative Movement Speed
A: Truing Start Position
B: Truing End Position
Number | Date | Country | Kind |
---|---|---|---|
2013-073593 | Mar 2013 | JP | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/JP14/58791 | 3/27/2014 | WO | 00 |