Surface Grinding Method

Abstract

To provide a surface grinding method capable of correctly determining completion of surface grinding of grinding a surface of a workpiece by removing a case that is hard to determine and due to magnitude of a power value or noise generated when the power value is set to a reference value of the determination.SOLUTION: A surface grinding method according to the present invention is a surface grinding method of grinding a surface of a cylindrical workpiece 100 including, while grinding the surface of the workpiece 100 using a grind stone 120, causing probes 132, 142 of dimension measurement devices 130, 140 to contact with the surface being ground to detect deviation of the dimension of the surface, and determining that the surface grinding is completed when the deviation of the dimension of the surface during grinding of the surface of the workpiece 100 is within a first predetermined value.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a surface grinding method for grinding the surface of a cylindrical workpiece. [Background technology]

[0002] Conventionally, surface grinding (black scale grinding) is performed at a slower cutting speed than main grinding in order to remove distortion of the workpiece and the oxide film (black scale) on the surface of the workpiece. After a predetermined time has elapsed, the cutting speed for surface grinding is switched to the cutting speed for main grinding (rough processing), and main grinding is performed.

[0003] However, there is variation in the amount of distortion on the machined surface of a workpiece. Therefore, if a sufficiently long time is set as the surface grinding time assuming a workpiece with large distortion, even a workpiece with small distortion that does not require a long time for surface grinding will be given a long surface grinding time just like a workpiece with large distortion. As a result, unnecessary surface grinding time is set for a workpiece with small distortion, leading to a long cycle time.

[0004] Therefore, for example, in the grinding method of Patent Document 1, a value (electric power) corresponding to the grinding resistance is detected during surface grinding, fluctuations in the detected value are monitored, and when it is determined that the amplitude of the fluctuations in the detected value has fallen below a certain level, the infeed rate is switched from the infeed rate for surface grinding to the infeed rate for main grinding. According to Patent Document 1, this method can effectively prevent damage to the grinding wheel at the start of grinding while shortening the cycle time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-292560 Summary of the Invention [Problem to be solved by the invention]

[0006] When using power as a detection value corresponding to grinding resistance as in Patent Document 1, if the power value is extremely small, it is difficult to determine that the amplitude of fluctuation in the detection value has fallen below a certain level. For example, in the case of raceway surface grinding (R shape), the power fluctuation immediately after contact with the grinding wheel is small, making it difficult to make such a determination.

[0007] In addition, in Patent Document 1, the difference between the maximum detected value stored during surface grinding and the updated detected value is sequentially calculated. Then, when this difference (power difference) remains below a preset tolerance for a predetermined period of time or longer, it is determined that the amplitude of the fluctuation in the detected value has fallen below a certain level. However, with this configuration, if noise is present in the power value, the maximum value will increase inaccurately. Since the maximum value is no longer updated after that, it becomes impossible to determine whether the amplitude of the fluctuation in the detected value has fallen below a certain level.

[0008] In view of these problems, the present invention aims to provide a surface grinding method that can accurately determine the completion of surface grinding of the surface (black scale) of a workpiece by excluding cases where it is difficult to make a judgment due to the magnitude of the power value or noise that occurs when the power value is used as the reference value for judgment. [Means for solving the problem]

[0009] In order to solve the above problems, a typical configuration of the surface grinding method according to the present invention is a surface grinding method for grinding the surface of a cylindrical workpiece, characterized in that while the surface of the workpiece is ground with a grinding wheel, a probe of a dimension measuring device is brought into contact with the surface being ground to detect dimensional deviations of the surface, and when the dimensional deviations of the surface while the surface of the workpiece is being ground become within a first predetermined value, it is determined that the surface grinding is complete.

[0010] The probe of the dimension measuring device is in contact with the surface of the cylindrical workpiece at two points symmetrical to the axis of the workpiece, and the deviation in the dimension of the surface is detected by adding up the displacements at the two points.

[0011] Before grinding with the grindstone, the workpiece is rotated and the dimensional deviation of the surface is detected by a dimension measuring device, and if the dimensional deviation of the surface is equal to or greater than a second predetermined value, the workpiece is determined to be a non-conforming product.

[0012] Before grinding with the grindstone, the workpiece is rotated while detecting any dimensional deviations on the surface using a dimension measuring device, and the greater the deviations in the surface dimensions, the slower the cutting speed of the grindstone is.

[0013] After the surface grinding is completed, main grinding is performed at a faster cutting speed than the surface grinding, and then finish grinding is performed at a slower cutting speed than the main grinding. After that, the deviation in the surface dimensions is detected using a dimension measuring device, and if the deviation in the surface dimensions is equal to or greater than a third predetermined value, the product is judged to be non-conforming. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a surface grinding method that can accurately determine the completion of surface grinding, which grinds the surface of a workpiece, by excluding cases where it is difficult to make a judgment due to the magnitude of the power value or noise that occurs when the power value is used as the reference value for judgment. [Brief explanation of the drawings]

[0015] [Figure 1] 1A to 1C are schematic views illustrating a usage mode of the surface grinding method according to the present embodiment. [Figure 2] 1 is a graph illustrating the relationship between dimensional runout of the surface of a workpiece and time when surface grinding is performed. [Figure 3] 1 is a graph illustrating the relationship between dimensional runout of the surface of a workpiece and time when surface grinding is performed. [Figure 4] 1 is a graph illustrating the relationship between dimensional runout of the surface of a workpiece and time when surface grinding is performed. [Figure 5] 10 is a graph illustrating the relationship between the measured dimensional runout of the surface of the workpiece and the time required to complete surface grinding. DETAILED DESCRIPTION OF THE INVENTION

[0016] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values shown in the embodiments are merely examples for facilitating understanding of the invention and, unless otherwise specified, do not limit the present invention. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0017] FIG. 1 is a schematic diagram showing how the surface grinding method (black scale grinding method) of this embodiment is used. FIG. 1(a) illustrates an example of grinding the outer surface 100a of a cylindrical workpiece 100. FIG. 1(b) illustrates an example of grinding the inner surface 100b of the cylindrical workpiece 100. In the surface grinding method of this embodiment, the surface of a cylindrical workpiece 100 as shown in FIGS. 1(a) and 1(b) is ground.

[0018] When grinding the outer surface 100a of the cylindrical workpiece 100, as shown in Fig. 1(a), a grinding wheel 120 that grinds the surface of the workpiece 100 and probes 132 and 142 of dimension measuring devices 130 and 140 that detect dimensional deviations on the surface of the workpiece 100 are placed on the outer surface 100a of the workpiece 100. When grinding the inner surface 100b of the cylindrical workpiece 100, as shown in Fig. 1(b), a grinding wheel that grinds the surface of the workpiece 100 and probes 132 and 142 of dimension measuring devices 130 and 140 that detect dimensional deviations on the surface of the workpiece 100 are placed on the inner surface 100b of the workpiece 100.

[0019] As the dimension measuring device, a so-called sizing device can be used. In addition, in the present invention, "variation in surface dimension" is synonymous with "variation in surface position" or "fluctuation range of surface position."

[0020] In the surface grinding method of this embodiment, while the surface of the workpiece 100 (see FIGS. 1(a) and 1(b)) is ground by the grindstone 120, probes 132, 142 of dimension measuring devices 130, 140 are brought into contact with the surface being ground (outer surface 100a or inner surface 100b) to detect dimensional deviation of the surface. Then, when the dimensional deviation of the surface during grinding of the surface of the workpiece 100 falls within a first predetermined value, it is determined that the surface grinding is complete.

[0021] In particular, in this embodiment, two dimension measuring devices 130 and 140 are arranged relative to the workpiece 100, and the probes 132 and 142 of the dimension measuring devices 130 and 140 are in contact with the surface of the cylindrical workpiece 100 at two axially symmetrical positions, and the displacements at the two positions are added together to detect dimensional deviations on the surface of the workpiece 100. This makes it possible to reliably detect dimensional deviations on the surface.

[0022] 2, 3, and 4 are graphs illustrating the relationship between time and the dimensional runout of the surface of the workpiece 100 when surface grinding is performed. The workpiece 100 to be surface ground has an outer diameter of 62.8 mm, an inner diameter of 55.0 mm, and a width of 24.0 mm. In the example shown in FIGS. 2 to 4, the set time (t1-t2) for surface grinding is 2 seconds, and the first predetermined value of the dimensional runout of the surface used to determine the completion of surface grinding is 10 μm.

[0023] In Figures 2-4, surface grinding is performed between times t1 and t2 (2 seconds). Then, at time t2, the cutting speed for surface grinding is switched to the cutting speed for main grinding, and main grinding is performed until time t3. Once main grinding is complete, the cutting speed for main grinding is switched to the cutting speed for finish grinding, and finish grinding is performed between times t3 and t4. Once finish grinding is complete, zero cut processing is performed between times t4 and t5.

[0024] FIG. 2 shows an example of surface grinding of a workpiece 100 having a surface dimensional runout of 17 μm before surface grinding. For a workpiece 100 having a surface dimensional runout of 17 μm before surface grinding, i.e., a workpiece 100 having a small surface dimensional runout, surface grinding begins (t1) as shown in FIG. 2, and immediately thereafter, at time tA, the surface dimensional runout of the workpiece 100 is equal to or less than a first predetermined value. Therefore, for a workpiece having a surface dimensional runout of 17 μm before surface grinding, surface grinding is completed in time "t1 - tA." Therefore, it can be seen that the time between "tA - t2" can be reduced.

[0025] FIG. 3 shows an example of surface grinding of a workpiece having a 35 μm runout of the surface dimension before surface grinding. For a workpiece 100 having a 35 μm runout of the surface dimension before surface grinding, i.e., a workpiece 100 having a certain degree of runout of the surface dimension, surface grinding begins (t1) as shown in FIG. 3. Then, at time tB, which is earlier than the set end time t2 of surface grinding, the runout of the surface dimension of the workpiece 100 becomes equal to or less than the first predetermined value. Therefore, for a workpiece having a 35 μm runout of the surface dimension before surface grinding, surface grinding is completed in time "t1 - tB." Therefore, it can be seen that the time between "tB - t2" can be reduced.

[0026] 4 shows an example of surface grinding of a workpiece having a 50 μm runout in the surface dimension before surface grinding. For a workpiece 100 having a 50 μm runout in the surface dimension before surface grinding, i.e., a workpiece 100 having a large runout in the surface dimension, surface grinding is started (t1) as shown in FIG. 4, and at time tC after the set end time t2 of surface grinding has elapsed, i.e., during main grinding, the runout in the surface dimension of the workpiece 100 becomes equal to or less than a first predetermined value. Therefore, for a workpiece 100 having a 50 μm runout in the surface dimension before surface grinding, it is necessary (or insufficient) to perform surface grinding for a time longer than the set time (t1-t2: for example, 2 seconds).

[0027] Figure 5 is a graph illustrating the relationship between the measured dimensional runout of the surface of the workpiece 100 and the time to complete surface grinding. Figure 5 plots the dimensional runout of the surface of several samples and the time to complete surface grinding when the present invention is applied. In Figure 5, the ideal line is the line when the grinding speed is 15 μm.

[0028] As shown in Figure 5, the average runout of the samples in this experiment was 29.6 μm. And because the intersection point between the approximate curve for grinding completion time and the average runout value of 29.6 μm is 1.5 seconds, we can say that the average grinding completion time is 1.5 seconds. This shows that an overall reduction of 0.5 seconds can be achieved compared to when the surface grinding time is set to a fixed 2 seconds. Because the number of workpieces processed per day is very large, a reduction of 0.5 seconds in cycle time can significantly increase the number of workpieces that can be processed.

[0029] Furthermore, when the runout is large, the time required to complete the grinding can be increased, which is significant for improving the accuracy of the subsequent main grinding. In other words, the time required for surface grinding can be optimized according to the runout of the surface dimensions, thereby improving manufacturing efficiency.

[0030] As described above, according to the surface grinding method of this embodiment, the dimensional fluctuation of the surface of the workpiece 100 is detected using the dimensional fluctuation of the surface, i.e., analog values, detected by the dimension measuring devices 130 and 140, rather than the power value, i.e., digital value, as in the conventional method, and the completion of surface treatment is determined based on the detected value. Therefore, it is possible to exclude cases where it is difficult to determine due to the magnitude of the power value or noise that occurs when the power value is used as the reference value for determination, and to accurately determine the completion of surface grinding of the surface of the workpiece 100.

[0031] Furthermore, according to the surface grinding method of this embodiment, it is possible to grasp the time required for surface grinding according to the dimensional variation of the surface of the workpiece 100 before surface grinding. As a result, it is possible to set the surface grinding time according to the dimensional variation of the surface of the workpiece 100, whereas in the past it was set uniformly regardless of the magnitude of the dimensional variation of the surface of the workpiece. Therefore, it is possible to optimize the time required for surface grinding and improve manufacturing efficiency.

[0032] Preferably, before grinding with the grinding wheel 120, i.e., before time t1 when surface grinding starts, the workpiece 100 is rotated while the dimension measuring devices 130, 140 detect any deviation in the surface dimension, and if the deviation in the surface dimension is equal to or greater than a second predetermined value, the workpiece 100 is determined to be non-conforming. This makes it possible to exclude workpieces 100 with significantly large deviations in the surface dimension from being processed in advance.

[0033] Furthermore, before grinding with the grindstone, i.e., before time t1 when surface grinding begins, the workpiece 100 is rotated while the dimension measuring devices 130 and 140 detect any variation in the surface dimension, and the greater the variation in the surface dimension, the slower the cutting speed of the grindstone is. If the surface dimension of the workpiece 100 varies significantly, a fast cutting speed will result in greater damage to the grindstone. Therefore, by reducing the cutting speed of the grindstone 120 as the surface dimension varies, as in the above configuration, it is possible to effectively prevent wear and damage to the grindstone 120 during the subsequent grinding process.

[0034] Furthermore, as described above, in the surface grinding method of this embodiment, once surface grinding is completed (time t2), main grinding, which has a faster cutting speed than the surface grinding, is performed (time t2-t3), and then finish grinding, which has a slower cutting speed than the main grinding, is performed (time t3-t4). Preferably, after finish grinding (time t3-t4), the dimension measurement devices 130-140 detect any deviation in the surface dimensions, and if the deviation in the surface dimensions is greater than or equal to a third predetermined value, the product is deemed to be non-conforming. This allows products that do not meet the desired specifications after finish grinding to be rejected.

[0035] That is, when detecting grinding resistance (power) as in Patent Document 1, only fluctuations during grinding can be observed, but when acquiring dimensions as in this invention, the surface condition before and after grinding can also be known. This makes it possible to exclude non-conforming products before and after grinding, and to change the cutting speed depending on dimensional fluctuations, thereby further improving manufacturing efficiency.

[0036] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention. [Industrial Applicability]

[0037] The present invention can be used as a surface grinding method for grinding the surface of a cylindrical workpiece. [Explanation of symbols]

[0038] 100... workpiece, 100a... surface, 100b... surface, 120... grinding wheel, 130... dimension measuring device, 132... probe, 140... dimension measuring device, 142... probe

Claims

1. A surface grinding method for grinding a surface of a cylindrical workpiece, comprising: Before grinding with a grinding wheel, a probe of a dimension measuring device is brought into contact with a surface of the workpiece while rotating the workpiece to detect dimensional deviation of the surface; According to the dimensional fluctuation of the surface, the larger the fluctuation, the smaller the cutting speed of the grindstone; While grinding the surface of the workpiece with the grindstone, a probe of the dimension measuring device is brought into contact with the surface being ground to detect dimensional deviation of the surface; A surface grinding method characterized in that it is determined that surface grinding is complete when dimensional deviation of the surface during grinding of the workpiece falls within a first predetermined value.

2. The probe of the dimension measuring device is in contact with the surface of the cylindrical workpiece at two axially symmetrical positions of the workpiece, 2. The surface grinding method according to claim 1, wherein the displacements at the two locations are added together to detect dimensional deviation of the surface.

3. Before grinding with the grindstone, the workpiece is rotated while detecting dimensional deviation of the surface with the dimension measuring device; 3. The surface grinding method according to claim 1, wherein the product is judged to be unsuitable if the deviation in the surface dimension is equal to or greater than a second predetermined value.

4. Once the surface grinding is complete, Main grinding is performed at a cutting speed greater than that of the surface grinding, After performing finish grinding at a cutting speed slower than that of the main grinding, the dimensional deviation of the surface is detected by the dimension measuring device; 4. The surface grinding method according to claim 1, wherein the product is determined to be non-conforming when the dimensional deviation of the surface is equal to or greater than a third predetermined value.

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