JP2022046298A - Grinder and grinding method - Google Patents

Abstract

To provide, with respect to grinding of a workpiece having a non-circular cross section, a grinder and a grinding method by which highly accurate grinding is possible while a cycle time of grinding is shortened.SOLUTION: A grinder for grinding a workpiece 20 having a non-circular cross section, includes: a main shaft 12 for rotating the workpiece 20; a grindstone 11 that is rotated and driven; a nozzle 16 that emits a grinding liquid to a grinding point; a grinding liquid variable device 35 that adjusts an amount of ejection of the grinding liquid; and control means 30 that controls the grinding liquid variable device 35; where the control is such that the amount of ejection of the grinding liquid is synchronized with a rotation phase angle of the main shaft 12.SELECTED DRAWING: Figure 2

Description

The present invention relates to a grinding machine and a grinding method for efficiently and accurately grinding a workpiece having a non-circular cross section.

In the grinding of a workpiece, in order to prevent grinding burn due to grinding heat, a grinding liquid is discharged to the grinding point to lower the temperature of the grinding point. In this case, even in the fine grinding following the rough grinding, if a large amount of the grinding fluid is injected into the grinding point, the shape accuracy of the workpiece may be deteriorated due to the bending of the workpiece due to the dynamic pressure of the grinding fluid. Therefore, during rough grinding where a large amount of grinding heat is generated, a large amount of grinding fluid is supplied in order to lower the temperature at the grinding point, and since the grinding heat is small after rough grinding, the generation of dynamic pressure is suppressed. A method of switching the flow rate of the grinding fluid by supplying a small amount of the grinding fluid has been proposed.

In addition, various techniques for solving the problem of the grinding fluid flow rate switching method have been proposed. The grinding fluid supply method described in Patent Document 1 measures the machining diameter of a workpiece during grinding, and reduces the flow rate of the grinding fluid when the reduction rate of the measured machining diameter becomes a predetermined value or less. It is a thing. As a result, even if the feed rate of the grindstone is switched, the flow rate of the grinding fluid is not reduced while the grinding amount is large, and grinding burn and thermal strain due to insufficient flow rate of the grinding fluid are prevented.

The grinding machine described in Patent Document 2 is provided with a back-off executing means for backing off the grindstone base after the rough grinding is completed and before the coolant flow rate is switched from the large flow rate to the small flow rate, so that the coolant is small. The bending of the work piece due to the decrease in dynamic pressure when switching to the flow rate can be released in the back-off state of the grindstone, that is, in the state where the work piece is away from the grindstone, and the cutting of the grindstone due to the change in dynamic pressure can be performed. I try not to cause it.

Japanese Patent Application Laid-Open No. 2003-94335 Japanese Unexamined Patent Publication No. 2011-31366

However, the techniques disclosed in Patent Documents 1 and 2 are all techniques on the premise that the grinding fluid is switched to a small amount in the fine grinding to prevent the workpiece from bending due to the dynamic pressure of the large amount of the grinding fluid. there were. On the other hand, in the grinding of a workpiece having a non-circular cross section, the deterioration of the shape accuracy of the workpiece due to the change in the amount of deflection of the workpiece due to the dynamic pressure of the grinding fluid due to the change in the rigidity of the workpiece during rotation is also a problem. Become.

For this reason, in the grinding of a workpiece having a non-circular cross section, the cutting speed is reduced as well as the rotation speed of the spindle, but such grinding has a problem that the grinding cycle time becomes long. rice field. The techniques disclosed in Patent Documents 1 and 2 are not techniques for shortening the grinding cycle time.

The present invention solves the above-mentioned conventional problems, and is a grinding machine capable of high-precision grinding while shortening the grinding cycle time for grinding a workpiece having a non-perfect circular cross section. It is an object of the present invention to provide a grinding method.

In order to achieve the above object, the grinding machine of the present invention is a grinding machine that grinds a workpiece having a non-perfect circular cross section, and includes a spindle for rotating the workpiece, a grindstone that is driven to rotate, and the grindstone. It is provided with a nozzle for discharging the grinding liquid to the grinding point, a grinding liquid variable device for adjusting the discharge amount of the grinding liquid, and a control means for controlling the grinding liquid variable device, and the control is the rotation of the spindle. The control is characterized in that the discharge amount of the grinding fluid is synchronized with the phase angle.

The grinding method of the present invention is a grinding method for a grinding machine that grinds a workpiece having a non-perfect circular cross section, wherein the grinding machine includes a spindle for rotating the workpiece, a grinding machine that is driven to rotate, and the grinding machine. It is equipped with a nozzle that discharges the grinding liquid to the grinding point and a grinding liquid variable device that adjusts the discharge amount of the grinding liquid, and is characterized in that the discharge amount of the grinding liquid is synchronized with the rotation phase angle of the spindle. And.

According to the grinding machine and the grinding method of the present invention, by adjusting the discharge amount of the grinding fluid according to the rotation phase angle of the spindle, the shape accuracy is likely to deteriorate due to the bending of the workpiece due to the dynamic pressure of the grinding fluid. In the part, the amount of grinding liquid discharged can be reduced, and in the part where grinding burn is likely to occur, the amount of grinding liquid discharged can be increased, so it is not necessary to reduce the rotation speed of the spindle or the cutting speed of the grindstone. The minimum is sufficient, and high-precision grinding is possible while shortening the grinding cycle time.

In the grinding machine of the present invention, the discharge amount of the grinding liquid to be synchronized is preferably obtained based on the finished shape and dimensions of the workpiece, and in the grinding method of the present invention, the synchronization is performed. It is preferable to determine the discharge amount of the grinding fluid based on the finished shape and dimensions of the workpiece. According to this configuration, it becomes easy to determine an appropriate discharge amount according to the finish shape and dimensions of the workpiece.

Further, in the grinding machine of the present invention, the discharge amount of the grinding liquid to be synchronized is preferably obtained by grinding the workpiece in advance, and in the grinding method of the present invention, the synchronized grinding is performed. The amount of liquid discharged is preferably obtained by grinding the workpiece in advance. According to this configuration, the discharge amount of the grinding fluid is obtained by preliminary grinding under the same conditions as the actual grinding, which is advantageous in determining an appropriate discharge amount.

The effects of the present invention are as described above, and according to the present invention, by adjusting the discharge amount of the grinding fluid according to the rotation phase angle of the spindle, the shape accuracy is increased by the bending of the workpiece due to the dynamic pressure of the grinding fluid. In the part where deterioration is likely to occur, the amount of grinding liquid discharged can be reduced, and in the part where grinding burn is likely to occur, the amount of grinding liquid discharged can be increased, so that the rotation speed of the spindle and the cutting speed of the grindstone are reduced. This is unnecessary or minimal, and high-precision grinding is possible while shortening the grinding cycle time.

The external perspective view of the grinding machine which concerns on one Embodiment of this invention. The figure which added the block diagram which shows the exchange of a signal to the perspective view which shows the main part of the grinding mechanism which concerns on one Embodiment of this invention. The front view which shows the support state of the workpiece in FIG. The perspective view which showed the state which the spindle was rotated 90 ° from the state of FIG. The figure which showed the relationship between the grindstone and a work piece during grinding in one Embodiment of this invention. In one embodiment of the present invention, it is a side view showing the relationship between the grindstone and the workpiece with the change of the rotation phase angle of the spindle, and is the side view when the rotation phase angle of the spindle changes from 0 ° to 80 °. .. In one embodiment of the present invention, it is a side view showing the relationship between the grindstone and the workpiece with the change of the rotation phase angle of the spindle, and is the figure when the rotation phase angle of the spindle changes from 90 ° to 180 °. The flowchart of the grinding process by the grinding machine which concerns on one Embodiment of this invention. The figure which showed the shape of the workpiece registered in the grinding machine which concerns on one Embodiment of this invention. The flowchart which showed the determination process of the control parameter of the grinding fluid variable apparatus which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an external perspective view of a grinding machine 1 according to an embodiment of the present invention. FIG. 2 is a diagram in which a block diagram showing signal exchange is added to a perspective view showing a main part of the grinding mechanism 10. In FIG. 1, the grinding machine 1 has an external portion formed by a main body cover 2, and a grinding mechanism 10 having main parts such as a spindle 12 and a grindstone 11 shown in FIG. 2 inside a front door 3 provided on the main body cover 2. Is equipped with. The grinding mechanism 10 shown in FIG. 2 is controlled by the control means 30, and various operations and settings can be performed by the operation panel 5 shown in FIG. The control means 30 is an NC (numerical control) device in this embodiment.

In FIG. 2, the grindstone 11 is rotationally driven around the R axis by the grindstone drive motor 33. The grindstone 11 is provided on a grindstone stand (not shown), and the grindstone stand feed motor 34 moves the grindstone 11 integrally with the feed of the grindstone stand in the X-axis direction (front-back direction) orthogonal to the R axis. The spindle 12 is provided on a spindle base (not shown), and is rotationally driven around the C axis by the spindle servomotor 31.

A grinding fluid discharge nozzle 16 is arranged adjacent to the grindstone 11. Grinding liquid is discharged from the tip of the grinding liquid discharge nozzle 16 toward the grinding point where the workpiece 20 and the grindstone 11 are in contact with each other, and it is possible to prevent grinding burn due to grinding heat. The grinding fluid discharge nozzle 16 is supplied with the grinding fluid flowing from a pump (not shown) via the grinding fluid variable device 35. The control means 30 is a grinding fluid variable device 35 so as to synchronize the discharge amount (flow rate) of the grinding fluid from the grinding fluid discharge nozzle 16 with the rotation phase angle of the spindle 12 detected by the rotation phase angle detecting means 32 (encoder). To control. The details of this control will be described later.

FIG. 3 is a front view showing a support state of the workpiece 20 in FIG. In FIG. 3, for convenience, the ground portion of the workpiece 20 is shaded. As shown in FIG. 3, the work piece 20 is sandwiched between the pair of left and right spindle centers 13 and the tailstock shaft center 14, and one end of the support 15 is engaged with the shaft portion of the work piece 20. is doing. The other end of the support 15 is fixed to the spindle 12. According to this configuration, the support 15 rotates integrally with the rotation of the spindle 12 around the C axis, and the workpiece 20 also rotates integrally with this.

FIG. 2 shows a state in which the workpiece 20 is ground by rotation of the grindstone 11 about the R axis. In FIG. 2, the rectangular parallelepiped portion (see the shaded portion in FIG. 3) of the workpiece 20 is the grinding portion. Hereinafter, for convenience of explanation, the rectangular parallelepiped part which is the grinding part is referred to as a work piece 20. In the state of FIG. 2, the surface 20a of the workpiece 20 is ground. By rotating the spindle 12 by 360 °, the workpiece 20 is also rotated by 360 ° integrally with the spindle 12, and the four surfaces (surfaces 20a to 20d) of the workpiece 20 are ground.

FIG. 4 shows a state in which the spindle 12 is rotated by 90 ° from the state of FIG. The work piece 20 also rotates 90 ° integrally with the 90 ° rotation of the spindle 12, and the work piece 20 is in a vertical state. The grindstone 11 is advanced in the X-axis direction so that the contact of the grindstone 11 with the workpiece 20 is maintained while the workpiece 20 is rotated by 90 °. The X-axis direction is the feed direction of the grindstone table, but it is also the cutting direction of the grindstone 11 into the workpiece 20.

The support method of the workpiece 20 shown in FIGS. 2 to 4 is an example and may be appropriately changed, and is not limited to the method of supporting the workpiece 20 from both sides as in the examples of FIGS. 2 to 4. , A method of supporting on one side by using a vise chuck may be used.

Hereinafter, the grinding according to the present embodiment will be described more specifically. FIG. 5 shows the relationship between the grindstone 11 and the workpiece 20 during grinding. At the grinding point 21, the corner b of the workpiece 20 is in contact with the grindstone 11. In this state, a wedge-shaped wedge space 30 is formed between the grindstone 11 and the workpiece 20 in a side view, and the grinding liquid 17 discharged from the grinding liquid discharge nozzle 16 flows into the wedge space 30. Since the grinding fluid 17 is constantly discharged, dynamic pressure is generated in the grinding fluid 17 that has flowed into the wedge space 30.

In FIG. 5, assuming that the length of the surface of the workpiece 20 facing the grindstone 11 is the wedge length L, the wedge length L changes as the workpiece 20 rotates about the C axis. That is, the wedge length L changes momentarily in conjunction with the change in the rotational phase angle of the spindle 12 (see FIG. 2), and the size of the wedge space 30 changes momentarily accordingly. Therefore, even if the discharge amount of the grinding fluid 17 is the same, the dynamic pressure generated in the grinding fluid 17 changes. Hereinafter, how the wedge length L changes will be described with reference to FIGS. 6 and 7.

6 and 7 are side views showing the relationship between the grindstone 11 and the workpiece 20 as the rotation phase angle of the spindle 12 changes. In FIG. 6A, the workpiece 20 is in a vertical state. At this time, the rotation phase angle of the spindle 12 is set to 0 °. When the spindle 12 makes one rotation about the C axis (arrow r), the rotation phase angle changes from 0 ° to 360 °, and the workpiece 20 returns to the vertical state shown in FIG. 6A again. After that, the same operation is repeated every time one rotation is performed, and the time when the rotation phase angle changes from 0 ° to 360 ° is one cycle. During one cycle, the position of the C-axis of the spindle 12 is fixed, and the R-axis of the grindstone 11 moves in the X-axis direction with the rotation of the workpiece 20.

In the state of FIG. 6B (rotational phase angle of 15 °), the grinding point 21 is raised and the wedge length L is zero as compared with the state of FIG. 6A. In the state of FIG. 6 (c) (rotational phase angle of 80 °), the grinding point 21 is lowered and the wedge length L is larger than that of the state of FIG. 6 (b). In the state of FIG. 7 (d) (rotational phase angle of 90 °), the grinding point 21 is higher and the wedge length L is smaller than that of the state of FIG. 6 (c). In the state of FIG. 7 (e) (rotational phase angle of 165 °), the grinding point 21 is lowered and the wedge length L is larger than that of the state of FIG. 7 (d). In the state of FIG. 7 (f) (rotational phase angle 180 °), the grinding point 21 is higher and the wedge length L is smaller than in the state of FIG. 7 (e).

In the state of FIG. 7 (f) (rotation phase angle 180 °), the rotation for half a cycle is completed, and of the four surfaces of the workpiece 20, half of the surface 20b, all of the surface 20a, and half of the surface 20d are ground. And half the area of the four sides of the workpiece 20 is ground. When the workpiece 20 further rotates 180 ° from the state of FIG. 7 (f), the rotation of 360 ° for one cycle is completed, the unground surface is ground, and the entire four surfaces (surfaces 20a to 20d) are formed. It will be ground and returned to the state shown in FIG. 6 (a). That is, during one cycle, the grinding point 21 changes its position up and down, and the four surfaces of the workpiece 20 are ground while the wedge length L changes.

During this period, even if the discharge amount of the grinding fluid is the same, the dynamic pressure generated in the grinding fluid changes according to the change in the wedge length L. Further, during the rotation of the work piece 20, the work piece rigidity of the work piece changes according to the change of the wedge length L in the X-axis direction which is the cutting direction. In this embodiment, as will be described in detail later, by synchronizing the discharge amount of the grinding fluid with the rotation phase angle of the spindle 12, it is possible to prevent the workpiece from bending due to changes in the dynamic pressure of the grinding fluid and changes in the rigidity of the workpiece. The workpiece can be ground with high precision.

Further, with reference to FIGS. 6 and 7, it has been described that the discharge amount of the grinding fluid is adjusted according to the rotation phase angle of the spindle from the viewpoint of preventing the workpiece from bending due to the dynamic pressure of the grinding fluid. Not limited. Specifically, in the grinding of a work piece having a non-circular cross section, there may be a portion where grinding burn is likely to occur due to a change in the contact arc length or the work piece diameter due to the rotation of the work piece. The position of the portion can be calculated from the shape of the workpiece. Therefore, if the amount of grinding liquid discharged is increased at the rotation phase angle of the spindle corresponding to the portion, grinding burn can be prevented. Such control is particularly effective in rough grinding where a large amount of grinding heat is generated, and from the viewpoint of preventing the work piece from bending due to the dynamic pressure of the grinding fluid in the subsequent fine grinding, grinding is performed according to the rotation phase angle of the spindle. Control may be performed to adjust the liquid discharge amount.

Hereinafter, the grinding process by the grinding machine 1 will be described with reference to the flowchart of FIG. In the grinding process, the finish shape and dimensions of the workpiece are first determined (step 100). The shapes shown in FIGS. 9 (a) to 9 (l) are registered in the grinding machine 1 according to the present embodiment, and the operator may select a desired shape and input necessary dimensions. When the desired shape is not registered, FIG. 9 (m) or FIG. 9 (n) is selected so that the operator can input the desired shape. Except for the perfect circle in FIG. 9B, the cross section is a non-perfect circle.

When the finish shape and dimensions of the workpiece are determined, the machining conditions corresponding to them are automatically determined (step 101). Machining conditions are the rotation speed of the workpiece, the cutting amount, the cutting speed, and the like. More specifically, a control program for controlling the spindle servo motor 31 and the grindstone base feed motor 34 shown in FIG. 2 is created according to the finished shape and dimensions of the workpiece. As described with reference to FIGS. 6 and 7, when the workpiece 20 has a non-circular cross section, the grinding point 21 moves up and down every moment. Therefore, when the work piece 20 is rotated at a constant speed, the grinding resistance changes and the amount of deflection of the work piece 20 also changes, so that it becomes difficult to secure the shape accuracy. Therefore, in the grinding machine 1 according to the present embodiment, the rotation speed of the workpiece is automatically determined so that the grinding resistance during one rotation of the workpiece becomes substantially constant.

After the machining conditions are determined, the control parameters for controlling the grinding fluid variable device 35 are determined (step 102). The control parameter in the present embodiment is a set value for determining the operation by control. In FIG. 2, the control of the grinding fluid variable device 35 is a control in which the grinding fluid discharge amount from the grinding fluid discharge nozzle 16 is synchronized with the rotation phase angle of the spindle 12. Since the amount of grinding fluid to be synchronized differs depending on the shape and dimensions of the workpiece, new control parameters are required each time the shape and dimensions of the workpiece are switched to different ones.

Hereinafter, the determination of the control parameters will be described with reference to FIG. FIG. 10 is a flowchart showing a control parameter determination process. The method for determining the control parameters is not particularly limited, but can be roughly classified into two methods, one in which preliminary grinding is performed and the other in which preliminary grinding is not performed, and these may be used in combination. In this embodiment, an example will be described for each of the two methods, one in which preliminary grinding is performed and the other in which preliminary grinding is not performed. First, a case where preliminary grinding is performed will be described.

When performing preliminary grinding, a workpiece is installed on the grinding machine 1 (step 200). Subsequently, grinding is performed without changing the amount of grinding liquid discharged from the grinding liquid discharge nozzle 16 (see FIG. 2) (step 201), and preliminary grinding is completed (step 202). If the preliminary grinding is limited to the grinding within the range that does not reach the final finish size, the workpiece used for the preliminary grinding can be handled as a product by making the final finish size by regrinding.

After the pre-grinding, the shape accuracy of the workpiece after the pre-grinding is measured or the output tendency of the power value (hereinafter, simply referred to as “power value”) of the spindle servomotor 31 (see FIG. 2) is detected (step 203). ). The shape accuracy of the workpiece can be obtained from the target dimension in the preliminary grinding and the dimensional difference of the workpiece after the preliminary grinding, and this dimensional difference indicates the degree of deterioration of the shape accuracy. In addition, the output tendency of the electric power value can be detected by monitoring the electric power value during grinding, and the change in the electric power value can be regarded as the influence of the change in the grinding resistance and the dynamic pressure of the grinding fluid. , The amount of change in the power value indicates the degree of deterioration of the shape accuracy.

Hereinafter, the deterioration of the shape accuracy of the workpiece will be specifically described. As described with reference to FIGS. 6 and 7, when the workpiece 20 has a non-circular cross section, the grinding points 21 are repositioned up and down, and the workpiece 20 is ground while the wedge length L changes. Therefore, even if the discharge amount of the grinding fluid 17 is the same, the dynamic pressure generated in the grinding fluid 17 changes, and the bending amount of the work piece 20 also changes, which causes the deterioration of the shape accuracy of the work piece 20. Will be. Further, during the rotation of the work piece 20, the work piece rigidity of the work piece changes according to the change of the wedge length L in the X-axis direction which is the cutting direction. As the rigidity of the workpiece changes, the amount of deflection of the workpiece 20 due to the dynamic pressure of the grinding fluid also changes, which also causes deterioration of the shape accuracy of the workpiece 20.

The deterioration of shape accuracy due to the change in the dynamic pressure of the grinding fluid and the change in the rigidity of the workpiece are all related to the dynamic pressure of the grinding fluid. On the other hand, in the present embodiment, as described above, the rotation speed of the workpiece is determined so that the grinding resistance during one rotation of the workpiece becomes substantially constant. Therefore, the portion of the workpiece after preliminary grinding whose shape accuracy has deteriorated can be regarded as the portion where the shape accuracy has deteriorated due to the bending of the workpiece due to the dynamic pressure of the grinding fluid.

Further, since the finished shape and dimensions of the workpiece are determined in step 100 of FIG. 8, the relationship between an arbitrary position on the outer periphery of the workpiece and the rotation phase angle of the spindle servomotor 31 can be determined. Further, in FIG. 2, since the rotational phase angle of the spindle servomotor 31 can be detected by the rotational phase angle detecting means 32 (encoder), the relationship between the change in the power value and the rotational phase angle of the spindle servomotor 31 is also determined. It is possible.

Based on the above, the degree of deterioration of the shape accuracy of the workpiece due to the dynamic pressure of the grinding fluid can be derived, and the rotation phase angle of the spindle servo motor 31 corresponding to the portion where the shape accuracy has deteriorated can also be determined. .. Therefore, following step 203, the relationship between the rotational phase angle of the spindle 12 and the degree of deterioration of the shape accuracy of the workpiece is derived (step 204).

Subsequently, the control means 30 determines a control parameter that reflects this derivation result (step 205). In step 204, the relationship between the rotational phase angle of the spindle 12 and the degree of deterioration of the shape accuracy of the workpiece due to the dynamic pressure of the grinding fluid is derived, but the degree of influence of the dynamic pressure change is the degree of dimensional error. Alternatively, it can be considered to be linked to the degree of change in the power value. Therefore, if a conversion standard for converting the degree of dimensional error or the degree of change in power value into the adjustment value of the discharge amount of the grinding fluid is created in advance from the results of tests, etc., it corresponds to the rotation phase angle of the spindle. The amount of grinding fluid discharged can be obtained and the control parameters can be determined.

In the above example, the discharge amount of the grinding fluid is obtained from the dimensional error or the change amount of the electric power value, but these are examples and may be appropriately changed. For example, the grinding resistance may be measured and the amount of the grinding fluid discharged may be obtained from the value of the grinding resistance. Further, in the above example, the grinding fluid discharge amount is obtained from the change amount of the electric power value of the spindle servo motor 31, but the grinding fluid discharge amount is obtained from the change amount of the electric power value of the grindstone drive motor 33 (see FIG. 2). You may.

Next, regarding the determination of the control parameters, the case where the preliminary grinding is not performed will be described. In the example of FIG. 10, the control parameters are determined based on the finished shape and dimensions of the workpiece (step 206 of FIG. 10). The finish shape and finish dimensions of the workpiece are determined at the start of the grinding process as described above (step 100 in FIG. 8). When determining the control parameters, the existing data stored in advance in the control means 30 (see FIG. 2) may be appropriately utilized.

As the data stored in advance in the control means 30, the relationship between the rotation phase angle of the spindle and the discharge amount of the grinding fluid is derived for each shape of the workpiece in advance (before delivery of the grinding machine). The data that was used can be mentioned. Based on this data and the finish shape / dimensions of the workpiece determined in step 100 of FIG. 8, the grinding fluid discharge amount according to the finish shape / dimensions of the workpiece is obtained and controlled by performing arithmetic processing as appropriate. The parameters can be determined. The data derived in advance may be derived from the measurement results by actually performing grinding, may be derived by analysis, or may be derived by using these in combination.

Further, when the control parameter is determined without performing the preliminary grinding, the data for the control program generated at the time of creating the control program (step 101 in FIG. 8) may be utilized. Such data is data on the rotation speed of the spindle servo motor 31, data on the moving speed of the grindstone table feed motor 34, and the like. Since the rotation speed of the spindle servo motor 31 and the like are related to the grinding resistance and the like and the grinding fluid discharge amount, if the relationship between the rotation speed and the like of the spindle servo motor 31 and the grinding fluid discharge amount is obtained in advance, it is a control parameter. Can be determined.

Further, when the control parameter is determined without performing preliminary grinding, the grinding fluid discharge amount may be obtained from the wedge length L (see FIGS. 5 to 7). The wedge length L can be calculated once the finish shape and dimensions of the workpiece are determined (step 100 in FIG. 8). On the other hand, as described above, the dynamic pressure generated in the grinding fluid changes according to the change in the wedge length L, and the rigidity of the workpiece also changes. Therefore, the relationship between the wedge length L and the grinding fluid discharge amount should be obtained in advance. If so, the control parameters can be determined.

After the control parameter is determined, grinding is performed by synchronizing the discharge amount of the grinding fluid with the rotation phase angle of the spindle according to this control parameter (step 103 in FIG. 8). During this period, in FIG. 2, the control means 30 is a grinding fluid variable device so as to adjust the discharge amount from the discharge nozzle 16 according to the rotation phase angle of the spindle 12 detected by the rotation phase angle detection means 32 according to the control parameter. 35 is controlled. After that, when the work piece is finished to the target size, the grindstone and the work piece are separated from each other (step 104 in FIG. 8), and the grinding is completed.

Although one embodiment of the present invention has been described above, according to the present invention, it is possible to prevent deterioration of shape accuracy and grinding burn by adjusting the amount of grinding liquid discharged according to the rotation phase angle of the spindle. .. Such an effect may be obtained by reducing the cutting speed of the grindstone together with the rotation speed of the spindle to perform grinding, but in this case, the grinding cycle time becomes long.

In the present invention, the discharge amount of the grinding fluid is adjusted according to the rotation phase angle of the spindle, so that the discharge amount of the grinding fluid is reduced in the portion where the shape accuracy is likely to deteriorate due to the bending of the workpiece due to the dynamic pressure of the grinding fluid. Since it is possible to increase the discharge amount of the grinding fluid in the part where grinding burns are likely to occur, it is not necessary or sufficient to reduce the rotation speed of the spindle and the cutting speed of the grindstone, and the grinding cycle time can be increased. High-precision grinding is possible while shortening the time.

Further, the object to be ground according to the present invention is a workpiece having a non-round cross section, but the non-round cross section has a spline, a keyway, an oil hole, etc., so that the non-round cross section is partially formed. It also includes those that have been formed.

1 Grinding machine 11 Grinding stone 12 Spindle 16 Discharge nozzle 17 Grinding liquid 20 Work piece 30 Control means 31 Spindle servo motor 32 Rotational phase angle detection means 35 Grinding liquid variable means

Claims (6)

A grinding machine that grinds workpieces with a non-circular cross section.
The spindle for rotating the work and
A grindstone that is driven to rotate,
A nozzle that discharges the grinding fluid to the grinding point and
A grinding fluid variable device that adjusts the discharge rate of the grinding fluid, and
It is provided with a control means for controlling the grinding fluid variable device.
The control is a grinding machine characterized in that the discharge amount of the grinding fluid is synchronized with the rotation phase angle of the spindle. The grinding machine according to claim 1, wherein the discharge amount of the grinding liquid to be synchronized is obtained based on the finished shape and dimensions of the workpiece. The grinding machine according to claim 1, wherein the discharge amount of the grinding liquid to be synchronized is obtained by grinding a workpiece in advance. A grinding machine for grinding workpieces with a non-circular cross section.
The grinding machine
The spindle for rotating the work and
A grindstone that is driven to rotate,
A nozzle that discharges the grinding fluid to the grinding point and
It is equipped with a grinding fluid variable device that adjusts the discharge amount of the grinding fluid.
A grinding method characterized in that the discharge amount of the grinding fluid is synchronized with the rotation phase angle of the spindle. The grinding machine according to claim 4, wherein the discharge amount of the grinding liquid to be synchronized is obtained based on the finished shape and dimensions of the workpiece. The grinding method according to claim 4, wherein the discharge amount of the grinding liquid to be synchronized is obtained by grinding the workpiece in advance.

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