JP3809670B2 - Grinding machine and control method thereof - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a grinding machine and a grinding machine control method, and more particularly to a grinding machine and grinding method suitable for a workpiece or the like that cannot accurately measure the dimension of a machined part during machining.
[0002]
[Prior art]
A grinding machine is a machine tool that contacts a workpiece with a rotating grindstone and moves the grindstone or workpiece by a predetermined amount in both the vertical and horizontal directions to machine the workpiece into a desired shape.
And in order to improve the grinding accuracy, measure the dimension of the processed part of the workpiece during the machining, especially near the completion of grinding, and adjust the fine grinding amount at the final stage so that the grinding amount does not become excessive. A method of setting is known (see Japanese Patent Application Laid-Open No. 57-194875).
[0003]
In other devices, the difference between the planned grinding amount and the actual grinding amount of the work piece is measured in the middle of grinding, and the grinding wheel feed speed is changed in the direction to cancel the difference. There has been proposed a method of controlling so as to be (see Japanese Patent Application Laid-Open No. 57-1948876).
[0004]
However, depending on the shape and size of the machined part, it may be difficult to measure the dimension of the machined part by bringing a measuring device into contact with or close to the workpiece during machining, so-called in-process measurement. The above method cannot be used. In addition, when the grindstone is pulled away from the workpiece during measurement and the dimensions are measured, there is a problem that such movement causes a new error.
[0005]
In order to deal with such problems, post-process measurement, that is, a method of inspecting a finished dimension after processing and setting subsequent grinding conditions based on the data is widely used.
For example, measure the processed part dimension of the workpiece before processing, use the difference from the desired dimension after processing as the target grinding amount of the grinding wheel, and set grinding conditions such as the grinding time of the grinding wheel so as to achieve the above grinding amount To do. In this method, since the dimensions before processing are measured, there is an advantage that the dimensions of the processed portion after processing can be made substantially the same even if the processing portion dimensions of the workpiece before processing vary.
[0006]
In addition, when machining the same workpiece many times, the transition of the actual grinding value with respect to the command value of the grinding amount, that is, the transition of the grinding characteristic with respect to the grinding number is pooled as past data, and the grinding conditions corresponding to the grinding number are pooled. There is also a way to change the settings. This is intended to cope with changes in grinding characteristics of the grindstone that change depending on the number of grinding.
[0007]
[Problems to be solved]
However, the conventional apparatus in the post process measurement has the following problems.
In the first method, where the processed part dimension of the workpiece is measured before machining and the difference from the desired dimension after machining is simply set as the target grinding amount of the grindstone, Although it is possible to cope with it, it is not possible to cope with changes in characteristics such as wear of the grinding wheel and wear.
[0008]
On the other hand, the method of pooling the changes in grinding characteristics corresponding to the number of grinding as data and changing the setting of the grinding conditions corresponding to the number of grinding based on this past data is the change of each grinding wheel. That is, it is impossible to cope with the change or individuality of individual characteristics of the grindstone.
The present invention has been made in view of such conventional problems, and can cope with variations in dimensions of a workpiece before processing, individual variations in characteristics of a grindstone, and changes over time. It is an object of the present invention to provide a highly accurate grinding machine and a grinding machine control method.
[0009]
[Means for solving problems]
A grinding machine according to a first aspect of the present invention includes a first main shaft that holds and rotates a workpiece, a second main shaft that holds and rotates a grindstone that grinds the workpiece, and the grindstone is close to the workpiece. Alternatively, the feed means for moving the first spindle or the second spindle so as to be separated, the detection means for measuring the dimension of the workpiece part before and after grinding, and the detection signal of the detection means are received by the feed means. On the other hand, the grinding machine has control means for instructing a feed operation amount O.
[0010]
The control means includes a storage means for recording a target value M of a processed part of the workpiece and a dimension before and after grinding of the processed part, and a pre-processing related to m recent workpieces stored in the recording means. position data D ₁ is the size of the working portion of _{the, D 2, D 3 ··· D} m and the dimension of the working portion of the processed position data _{d 1, d 2, d 3} ··· d m and the target And a calculation means for calculating the feed operation amount O based on the value M.
[0011]
Then, the calculation means calculates the target grinding amount S _i represented by M−D _i (i = 1, 2,... M) for each of the m workpieces and D _i −d _i (i = 1, 2,... M) is calculated as a difference value E _i (= M + d _i −2D _i ) from the actual grinding amount s _i, and an average value E _a of m difference values E _i is calculated. A correction amount is calculated on the basis of this, and the feed operation amount O is calculated by correcting the feed operation amount derived from an equation including the function f (S) using the next or subsequent target grinding amount S. That is, based on the recent tendency of the difference value Ei (error or correction) between the target grinding amount S _i and the actual grinding amount s _i , the control operation or target grinding amount so far is corrected. Such correction calculation may be performed every time before machining, but since the change in the characteristics of the machine gradually changes, it may be performed at an appropriate interval.
[0012]
The grinding machine of the present invention measures position data, which is a processing dimension before processing the workpiece next time or next time, and uses a target grinding amount S for the next time or the next time calculated based on the position data. Since the feed operation amount O derived from the equation including f (S) is set, the finished dimension does not fluctuate even if the pre-working dimension of the workpiece varies.
The error (correction) of recent devices obtained by previous measurements of grinding the next time or next time, i.e., because to be reflected in the subsequent grinding control operation by detecting the trend of the average value E _a difference value E _i , It can always be close to the target machining value with high accuracy. That is, highly accurate operating characteristics can be maintained by reflecting changes in characteristics over time such as wear of the grinding wheel.
[0013]
As described above, according to the present invention, it is possible to provide a highly accurate grinding machine that can cope with the dimensional variation of the workpiece before processing, the change with time of the characteristics of the grindstone, and the individual variation. I can do it.
In the above, the number m of the data for which the error or the average value E _a of the correction E _i is taken is suitably 5 to 15 as described in claims 2 and 4 . If the number m of data is too large, old data (characteristics) will be reflected in the next control, so the number m of data is suitably 15 or less. In addition, if the number of data m is too small, the influence is reflected in the case where a special factor having no reproducibility occurs, so that the number of data m is appropriately 5 or more.
[0014]
The invention described in claim 3 is a grinding machine control method based on a control mode similar to that of the grinding machine. That is, according to the present invention, the position data D ₁ , D ₂ , D ₃ ... D _m which are dimensions of the machined part before machining on the recent m workpieces and the machined part dimensions after machining. Based on the position data d ₁ , d ₂ , d ₃ ... _Dm and the target value M, M−D _i (i = 1, 2,... M) for each of the m workpieces. A difference value E _i (= M + d _i −2D _i ) between the target grinding amount S _i expressed by the following equation and the actual grinding amount s _i expressed by D _i −d _i (i = 1, 2,... M _). ), A correction amount is calculated based on the average value E _a of the m difference values E _i , and a feed operation derived from an equation including a function f (S) using the target grinding amount S at or after the next time Correct the amount . As a result, the same effect as that of the invention of claim 1 can be obtained.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
In this example, as shown in FIG. 1, a first main shaft 11 that holds and rotates a workpiece 81, a second main shaft 15 that holds and rotates a grindstone 16 that grinds the workpiece 81, and a grindstone 16 The feed means 21 and 22 for moving the first main shaft 11 and the second main shaft 15 so as to be close to or away from the workpiece 81, and the dimensions of the processing parts 811 and 812 of the workpiece 81 before and after processing. Sending operation amount O is commanded to detection means 31 and 32 for measuring, and drive circuits 212 and 222 of motors 211 and 221 for receiving detection signals x1 and x2 of the detection means 31 and 32 and driving the sending means 21 and 22. It is a grinding machine 1 having a control means 40 to perform.
[0016]
As shown in FIG. 2, the control means 40 includes a storage means 41 that records a target value M of the dimension of the processed part of the workpiece 81 and a dimension of the processed part before and after grinding , and a recent value stored in the recording means 41. the m position data is the size of the processing unit before processing relating workpiece D _1, D _2, D ₃ position data d ₁ of the · · · D _m and after _{processing, d 2, d 3 ··· d} m And calculating means 42 for calculating the feed operation amount O based on the target value M, and a command section 43 for instructing the feed operation amount O to the drive circuits 212 and 222 based on the calculation result of the calculation means 42 ; the it has.
[0017]
The computing means 42 is represented by a target grinding amount S _i represented by M−D _i (i = 1, 2,... M) and D _i −d _i (i = 1, 2,... M). The difference value E _i (= M + di−2Di) from the actual grinding amount s _i calculated is calculated, and m difference values E expressed by (Σ _{i = 1,2, .. m} E _i ) / m calculating a manipulated variable O feed by correcting the feed amount of correction derived by the formula comprising _i of the average value E next calculates the correction amount based on _a or the next time the target grinding amount function with S f (S) To do.
The following is a supplementary explanation for each.
[0018]
As shown in FIG. 1, the grinding part for processing the workpiece 81 in the grinding machine 1 includes a grindstone 16, a second spindle 15 for rotating the grindstone 16, and a first spindle 11 for holding and rotating the workpiece 81. And feed means 21 and 22 for moving the first main shaft 11 and the second main shaft 15.
The detection means includes a first detection means 31 for measuring the dimension of the processed part 811 before grinding the workpiece 81, and a second detection means 32 for measuring the dimension of the processed part 812 after grinding by the grindstone 16. Consists of. The first and second detection means may be the same. In the figure, reference numeral 89 denotes an input means for inputting the target value M and the like.
[0019]
As shown in FIG. 2, the storage means 41 of the control means 40 records a target value memory 411 for recording the target value M and position data D _i (i = 1, 2,... M) before processing. The first measurement value memory 412 and the second measurement memory 413 in which the post-processing position data d _i (i = 1, 2,... M) are recorded.
Based on the target value M and the position data D _i before machining, the calculation means 42 uses M−D _i (i = 1, 2,... M) for each of the m workpieces. A first calculation unit 421 that calculates a target grinding amount S _i represented is included , and the result is sequentially stored in the target grinding amount memory 422.
[0020]
The arithmetic unit 42 includes a second arithmetic unit 423 for calculating the position data d _i after processing the position data D _i before processing, the actual amount of grinding _{s i (= D i -d i} ), This value is sequentially stored in the actual grinding amount memory 424.
Then, in the third calculation unit 426 provided in the correction value calculation unit 423, the feed operation amount for the motor drive circuit 212 is calculated from the latest m pieces of data stored in the target grinding amount memory 422 and the actual grinding amount memory 424. The future correction amount α of O is calculated by the following equation. Then, the correction amount α is recorded in the correction memory 427.
[0021]
α = k × {Σ _{i = 1,2, .. m} (S _i −s _i ) / m} (2)
If the previous correction amount α ₀ is already included in addition to the function f (S) in the feed operation amount O up to the previous time, which is the basis of the above data, the correction amount α for the next and subsequent times is , Modify as follows.
α = k × {Σ _{i = 1,2, .. m} (S _i −s _i ) / m} + α ₀ (2 ′)
[0022]
Then, the operation amount calculation unit 428 calculates the feed operation amount O corrected by the following equation with respect to f (S) calculated based on the next or subsequent target grinding amount S.
O = f (S) + α (3)
The command unit 43 commands the feed operation amount O to the drive circuit 222 of the grindstone feed motor 221. In addition, a feed operation amount O corresponding to the grinding width of the machining portions 881 and 882 is commanded to the feed motor 222 of the workpiece 81.
[0023]
As described above, according to the grinding machine 1 of this example, the dimension of the workpiece 81 before processing is measured, the next target grinding amount S is set based on the measured value, and this target grinding amount S is used. Since the feed operation amount O derived from the equation including the function f (s) is set, the variation in the dimension before processing does not affect the finished dimension. Further, by correcting the feed operation amount O based on the average value E _a described above, it is possible to cope with variations in dimensions after processing due to changes in characteristics of the grindstone 16 over time and individual variations of the grindstone 16 one by one. it can be.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a grinding machine according to an embodiment.
FIG. 2 is a diagram illustrating connection of a control unit and a signal flow of a grinding machine according to an embodiment.
[Explanation of symbols]
1. . . Grinder,
11. . . First spindle,
15. . . Second spindle,
16. . . Whetstone,
21,22. . . Feeding means,
31, 32. . . Detection means,
40. . . Control means,
81. . . Work piece,
811 812. . . process section,

Claims (4)

A first main shaft for holding and rotating the workpiece; a second main shaft for holding and rotating a grinding wheel for grinding the workpiece; and (2) Feeding means for moving the spindle, detecting means for measuring the dimensions of the workpiece part before and after grinding, and control means for instructing the feed operation amount O to the feeding means in response to a detection signal of the detecting means A grinding machine having
The control means includes a storage means for recording a target value M of a processed part after grinding of the work piece and a dimension before and after grinding of the processed part, and the latest m pieces of work pieces stored in the recording means. position data D ₁ is the size of the processing unit before processing _{relating, D 2, D 3 ··· D} m and the dimension of the working portion of the processed position data _{d 1, d 2, d 3} ··· d m And calculating means for calculating the feed operation amount O based on the target value M,
The arithmetic means calculates the target grinding amount S _i represented by M−D _i (i = 1, 2,... M) and D _i −d _i (i = 1) for each of the m workpieces. , 2, ... m) is calculated as a difference value E _i (= M + d _i -2D _i ) from the actual grinding amount s _i, and based on the average value E _a of the m difference values E _i. A grinding machine characterized in that the feed operation amount O is calculated by correcting a feed operation amount derived by an expression including a function f (S) using a target grinding amount S for the next time or after the next time after calculating a correction amount. . In claim 1, the number m of data for determining the average value E _a is grinding machine, characterized in that from 5 and 15. A first main shaft for holding and rotating the workpiece; a second main shaft for holding and rotating a grinding wheel for grinding the workpiece; and A control method of a grinding machine comprising a feed means for moving two spindles,
The target value M of the dimension of the processed part after grinding of the workpiece and the dimension before and after grinding of the processed part are recorded, and the position data which is the dimension of the processed part before processing related to the latest m workpieces stored. on the basis of the _{D 1, D 2, D 3} ··· D m and the position data d ₁ is the size of the processing portion after _{machining, d 2, d 3 ··· d} m and the target value M, the m For each of the workpieces, the target grinding amount S _i represented by M−D _i (i = 1, 2,... M) and D _i −d _i (i = 1, 2,... M). ) To calculate the difference value E _i (= M + d _i −2D _i ) from the actual grinding amount s _i, and calculate the correction amount based on the average value E _a of the m difference values E _i. A grinding machine control method, comprising: correcting a feed operation amount derived from an expression including a function f (S) using a target grinding amount S from the next time onward. In claim 3, the number m of data for determining the average value E _a, the control method of the grinding machine, characterized in that from 5 and 15.

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