JP2005007551A - Initial adjustment method of cutting depth - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To heighten the efficiency of machining by quickly completing the initial adjustment of cutting depth when a machining tool is replaced with a new one or corrected in finishing of the inner surface of a hole. <P>SOLUTION: When the machining tool such as a grinding wheel in the grinder is updated, since the machining resistance changes to cause a change in amount of flexibility of the machining tool and its shaft, there is the possibility that the deviation of the measurement value after machining from the target value continues for a long time. In his initial adjustment method of the depth of cut, after the tool is updated, a difference between the first measurement value after machining and the target value is calculated, and the difference value is taken as the result of flexibility of the machining tool in the first machining, and added to the depth of cut in the second machining to quickly make the measurement value after machining approximate the target value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a processing tool, for example, when a grinding wheel for grinding is replaced with a new one or when the outer diameter or the like is changed by adding dressing (shaping) or truing (shaping) to the processing tool. The present invention relates to an initial adjustment method of a cutting amount for adjusting an initial state in a processing method or a processing apparatus using the above.
[0002]
[Prior art]
For example, in a conventional internal grinding method in which the inner surface of a hole is polished and finished by a rotating grinding wheel, the dimension of the hole before machining is generally measured and required for the target dimension of the hole after machining. In addition to calculating the machining allowance, the cutting amount is calculated in consideration of the bending of the grinding wheel due to grinding resistance, and the grinding wheel is positioned so that the grinding wheel can be fed toward the workpiece by the calculated cutting amount. After that, perform the grinding process. Then, measure the hole size again after machining, and if there is a difference between the measured hole size and the target hole size, cut the grinding wheel into the workpiece again by that amount. Thus, the processing procedure usually performed is to bring the dimension measured after processing closer to the target dimension.
[0003]
When the grinding wheel has a large diameter and a thick shaft, and therefore the bending due to the grinding resistance is small, the grinding can be performed with high accuracy by a conventional processing method. However, if the hole diameter of the workpiece is small and the diameter of the grinding wheel is small accordingly, the grinding wheel and its shaft will bend due to grinding resistance, so the worn grinding wheel was replaced with a new one. When the grinding wheel is modified such as dressing or truing, the grinding resistance acting on the grinding wheel changes greatly, resulting in a change in the amount of deflection of the grinding wheel and its shaft, resulting in poor hole diameter machining accuracy. There was a problem of becoming.
[0004]
[Problems to be solved by the invention]
In view of the above-mentioned problems in the prior art, the present invention is used when a grinding wheel used for grinding is replaced, or when dressing or truing is corrected, that is, when the grinding wheel is "updated". A new tool for initial adjustment of the depth of cut that adjusts the depth of cut in response to changes in machining resistance when there is a change in machining resistance that generally affects the machining tool, such as changes in grinding resistance that occur. An object of the present invention is to solve the above-mentioned problems in the prior art by providing a simple method.
[0005]
[Means for Solving the Problems]
As a means for solving this problem, the present invention provides an initial adjustment method for a cutting amount described in claim 1 of the claims.
[0006]
According to the initial adjustment method of the depth of cut of the present invention, at least one machining step for machining the inner surface of the hole and two measurement steps for measuring the inner diameter of the hole of the workpiece before and after the machining are executed. When the machining tool is updated in the hole machining method, based on the first measurement step of measuring the inner diameter of the hole before machining the first workpiece, the target dimension, and the first measurement value A machining process for calculating a cutting amount of the machining tool, positioning the machining tool according to the cutting amount, and performing machining on the first workpiece, and processing the first workpiece A second measuring step for measuring the inner diameter of the hole, a first measuring step for measuring the inner diameter of the hole before processing the second workpiece, a target dimension and a first measurement. Calculate the cutting depth of the machining tool based on the value and target dimensions The value of the difference between the first workpiece and the second measured value is calculated, and the value of this difference is added to the previously calculated cutting amount to correct the cutting amount. A machining step that positions the machining tool according to the depth of cut and executes machining on the second workpiece, and the second time that measures the inner diameter of the hole in the machined second workpiece In the same way as for the second measurement workpiece and the second workpiece, the first measurement step, the machining step, and the second measurement step are sequentially executed for the third and subsequent workpieces. In the meantime, when it is continuously confirmed in a predetermined number of workpieces that the second measurement value is within the allowable range when viewed from the target dimension, the cutting amount at that time is maintained. The machining tool is positioned and the subsequent machining of the workpiece is continued.
[0007]
In this way, the dimension as the previous machining result is measured, the difference between the measured value reflecting the change in machining resistance acting on the machining tool and the target value is immediately calculated, and the difference value is automatically calculated. Therefore, the measured value after machining approaches the target value quickly. When the number of measured values after processing within the allowable range when viewed from the target value reaches a predetermined number, the cutting amount at that time is maintained as appropriate. Accordingly, since an appropriate cutting amount can be obtained quickly, the number of workpieces that are wasted during that time is reduced, the cost is reduced, and the machining efficiency is also increased.
[0008]
When the initial adjustment method of the cutting depth according to the present invention is expressed numerically, the target dimension of the hole to be processed is A, the scraping amount necessary to reach the target dimension A is G, and the preceding workpiece is processed after processing. The inner diameter of the measured hole is B, the difference between the value A and the value B is D, the deflection amount per unit load of the machining tool calculated from the accumulated machining data, that is, the deflection rate is a, and the sharpness of the machining tool is also calculated. When the correction value determined according to the shaving amount per unit time shown is b, and the correction value (positive or negative) of the cutting amount added manually when the cutting amount is determined by automatic control is c, the second and later The cutting amount H of the machining tool in machining the workpiece is calculated by the following mathematical formula, and the machining tool is positioned.
H = a × (G−c) + (b + D)
[0009]
Specifically, the initial adjustment method of the cutting depth according to the present invention is a grinding wheel in which the machining tool rotates around its own central axis, and the workpiece also rotates around its own central axis. It can be most preferably carried out in the grinding machine supported by the machine.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In this embodiment, since the present invention is applied to a grinding machine that grinds the inner surface of a small-diameter hole by a grinding wheel, a hole in a workpiece that is rotated separately from the grinding wheel that rotates itself. A method of performing initial adjustment of the cutting amount of the grinding wheel in the grinding machine for grinding the inner surface of the grinding wheel will be described in detail. However, it goes without saying that the present invention can be applied not only to a grinding machine but also to a processing device (machine tool) other than a grinding machine, such as a lathe, a drilling machine, or the like. In a processing apparatus other than a grinding machine, bending of a cutting tool, a drill or the like becomes a problem as a processing tool to replace a grinding wheel.
[0011]
In a grinding machine, when the grinding wheel used for grinding is replaced with a new one, or when the grinding wheel is "updated" by making modifications such as dressing (sharpening) or truing (shaping), the grinding wheel When the diameter of the grinding wheel is small, the grinding resistance changes due to a change in grinding resistance. Therefore, when the cutting depth is initially set by the conventional method, the machining accuracy and machining efficiency of the product are lowered. According to the present invention, when such a grinding wheel is renewed, the initial adjustment of the cutting depth is performed specifically according to the following procedure.
[0012]
FIG. 1 conceptually illustrates the configuration of a grinding machine 1 as a target for carrying out the initial adjustment method for the cutting depth according to the present invention. The grinding machine 1 is provided with a robot 2. The robot 2 includes arms 3 and 4 as link mechanisms. Further, a belt-like conveyor 5 is attached to the grinding machine 1. The conveyor 5 includes a number of pallets 6, and one workpiece can be placed on each pallet 6. Since the conveyor 5 moves in the direction of the arrow F, the pallet 6 sequentially passes through the movable range of the arm 4 of the robot 2. In addition, the mechanical structure of the grinding machine 1 may be the same as a grinding machine conventionally used. A feature of the present invention resides in a method of adjusting the position of the grinding wheel which is a processing tool after updating by controlling the operation of the grinding machine 1.
[0013]
The grinding machine 1 of the illustrated embodiment can grind a workpiece twice in succession. However, the number of grinding processes required in the present invention is at least one. In the illustrated embodiment, first, workpieces having small-diameter holes are picked up one by one from the pallet 6 just below by the arm 4 of the robot 2 and put into the first station 7 which is the starting point of the machining process. Is done. The workpiece moves from the first station 7 to the second station 8 on a transfer means such as a rotary table 9 that rotates intermittently in the direction of the arrow R, and stops at each station for a predetermined short time.
[0014]
In the second station 8, the first measurement is performed on the workpiece. The means for measurement is shown enlarged in FIG. The workpiece 10 as a raw material has a bottomed cylindrical shape as a whole, and a small-diameter hole 11 is formed at the bottom. The grinder 1 is used to precisely finish the cylindrical inner surface of the hole 11. In the measurement process as shown in FIG. 2 applied to the second station 8, the reference pin 12 having a slightly smaller surface shape is prepared according to the inner surface shape including the hole 11 of the workpiece 10. Yes. The reference pin 12 is inserted into the workpiece 10 by the operation of a means such as an air cylinder (not shown) when the workpiece 10 comes to the position of the second station 8 and stops.
[0015]
Each workpiece 10 is fixedly supported by a clamping means (not shown) at a predetermined position on the upper surface of the turntable 9. An opening 13 is formed in a portion of the peripheral portion of the turntable 9 that supports the workpiece 10. When the turntable 9 rotates and the opening 13 comes to the position of the second station 8 and temporarily stops, the opening 13 is connected to a fixed air passage (not shown). Thereby, compressed air pressurized to a predetermined pressure by a compressor (not shown) is supplied into the opening 13 as indicated by an arrow P.
[0016]
While the compressed air flows through the gap between the inner surface of the hole 11 of the workpiece 10 and the surface of the reference pin 12 facing it, the compressed air receives a squeezing action according to the size of the gap and the roughness of the surface. Causes pressure loss. Accordingly, the size of the gap 11 can be detected by measuring the pressure difference before and after the gap as in the case of a normal air micrometer, and the dimension of the hole 11 can be calculated from the value. A pressure difference detected by a differential pressure sensor (not shown) or the like is input to a control means such as an electronic control device (not shown) built in the operation panel 14 or 15 to be processed.
[0017]
The first workpiece 10 that has received the first dimension measurement at the second station 8 moves to the third station 16 again by the rotation of the rotary table 9 and temporarily stops at that position. In the third station 16, the first workpiece 10 is subjected to the first grinding by means as shown in an enlarged view in FIG. The grinding wheel 18 is initially in a neutral position as shown in FIG. 3, but quickly moves to a position (see FIG. 4) in contact with the inner surface of the hole 11 of the workpiece 10 according to the first measurement result. . This movement is called air cut. Substantially grinding starts when the grinding wheel 18 moves to a position where it comes into contact with the hole 11.
[0018]
Although the grinding mechanism is not shown in detail in FIGS. 3 and 4, the workpiece 10 is rotationally driven as indicated by an arrow D around the vertical axis 17 on the rotating table 9 that is stopped. Is done. The grinding wheel 18 having a radius r inserted into the hole 11 of the workpiece 10 is pushed toward the inner surface of the hole 11 after moving by the air cut amount E in the cutting direction indicated by the arrow C. Further, the grinding wheel 18 itself is also driven to rotate as indicated by an arrow S. 3 and 4, the scraping amount of the workpiece 10 is indicated by the reference symbol G. The actual scraping amount G is generally a small amount, but is exaggeratedly drawn in FIGS. 3 and 4.
[0019]
One of the objects of the present invention is, for example, in the grinding machine 1, when the grinding wheel 18 is replaced with a new one, when dressing is performed to restore the sharpness of the grinding wheel 18, or the shape of the grinding wheel 18 is changed. When a so-called “renewing of the grinding wheel” is performed, such as when truing is performed to correct, as a transient phenomenon, the inner diameter of the hole 11 does not match the target dimension A and must be discarded. The object is to reduce the cost by reducing the number of workpieces 10 that cannot be obtained as much as possible. Another object is to increase the production efficiency by giving the grinding wheel 18 renewed as described above as soon as possible with the optimum cutting amount H in consideration of the bending thereof.
[0020]
The initial adjustment method of the cutting amount according to the present invention is how to set the cutting amount in the immediately subsequent machining when a machining tool such as a grinding wheel is updated, that is, a support portion (not shown) of the grinding wheel 18. This is related to the problem of how far to move in positioning in the cutting direction C. In the present invention, the depth of cut is generally indicated as H, and the target dimension, that is, the target value of the inner diameter (radius) of the hole 11 to be reached by grinding is required to reach A and the target value A. Machining amount calculated empirically from past machining data, G is the amount of cut, B is the inner diameter of the hole 11 measured after machining in the workpiece 10 previously machined, D is the difference between value A and value B The bending rate of the tool is a, the correction value of the cutting amount according to the sharpness of the machining tool that can be determined by the amount of cutting per unit time is b, and the correction value of the cutting amount added manually in the case of automatic control is also c. Sometimes, considering the deflection of the grinding wheel 18 and its shaft 19 to achieve the target dimension A,
H = a × (G−c) + (b + D)
The cutting amount H calculated by the following mathematical formula is given.
[0021]
As is clear from FIG. 3, the following relations exist between the above-mentioned numerical values A, r, E, and G.
A = r + E + G
[0022]
In this case, since there is no measurement value B for the first workpiece 10 because there is no precedent for machining with a new machining tool, the measured value is limited to the first machining. Instead of B, the target dimension A is used. Therefore, in the first processing,
D = A−B = A−A = 0
And the above formula is
H = a × (G−c) + b
It becomes.
[0023]
When the first workpiece 10 is ground at the third station 16 on the grinding machine 1, the control circuit built in the operation panel 14 or 15 sets the cutting amount H calculated in this way. Accordingly, the support portion of the grinding wheel 18 is positioned and processing is performed. Since the bending of the grinding wheel 18 and its shaft 19 is taken into consideration, normally, H> G as shown in FIG. In this way, the rotating grinding wheel 18 grinds the inner surface of the hole 11 of the workpiece 10 that is still rotating.
[0024]
As a result, the inner diameter B of the hole 11 of the first workpiece 10 obtained is executed at the fourth station 20 after rotating the rotary table 9 to move the workpiece 10 to the fourth station 20. It is measured by the second measurement process. The second measurement step may be performed by a method similar to the air micrometer using the reference pin 12 and compressed air, or the other method may be used, as in the first measurement step shown in FIG. May be.
[0025]
When at least the second measurement at the fourth station 20 is completed, the measurement value B is obtained, so that D is calculated as the difference value of AB. The greater the difference value D, the greater the deflection of the grinding wheel 18 and the shaft 19, indicating that the grinding wheel 18 has largely escaped during processing. When all the data necessary for the present invention is obtained in this way, the above-described calculation formula H = a × (G−c) + (b + D)
By substituting the difference value D into, the value of the cutting depth H unique to the present invention is calculated.
[0026]
By setting this value retrospectively as the cutting depth H of the grinding process at the third station 16, the cutting depth H is increased by the amount that could not be processed due to the grinding wheel 18 and its shaft 19 being bent. A more appropriate cutting amount can be given to the workpiece 10. Therefore, even if the grinding wheel 18 and the shaft 19 have a problem of bending due to grinding resistance, the inner diameter of the hole 11 after processing the second workpiece 10 measured at the fourth station 20 approaches the target dimension A. Go. Further, the difference value D due to the measured value B for the second workpiece 10 at the fourth station 20 is substituted into the above-described calculation formula, and the depth of cut in the grinding of the third and subsequent workpieces 10 is calculated. Needless to say, H is further corrected. When it cuts too much, the cutting amount H is reduced. In this way, the inner diameter of the hole 11 measured after processing approaches the target dimension A as much as possible.
[0027]
In the embodiment shown in FIG. 1, since the fifth station 21 is provided, the workpiece 10 that has not reached the target dimension A as in the first workpiece 10 proceeds to the fifth station 21, and the above-described processing is performed. The inner diameter of the hole 11 is brought close to another target dimension A set for this stage by the second grinding process that gives the cutting depth H calculated by the same calculation formula as in the case. Thus, when performing a multi-step grinding process, the improvement of the precision according to it can be anticipated. Thereafter, the workpiece 10 passes through the third measuring step and the dimension after processing is measured, but this step is omitted in FIG.
[0028]
The initial adjustment method of the cutting depth according to the present invention can be carried out if there is at least one processing step and measurement steps before and after that. The feature is that the difference D between the target dimension A and the measured value B after machining is considered to be due to the bending of the machining tool and is added as a correction value for the cutting depth H. Needless to say, the difference value D may be a negative value. As a result, the optimum depth of cut H that achieves the target dimension A can be reached during the machining of a small number of workpieces 10, so that the number of workpieces 10 that are wasted can be reduced.
[0029]
In the illustrated embodiment, the workpiece 10 that has been ground is moved to the sixth station 22 by the rotation of the rotary table 9, so that the arm 4 of the robot 2 takes out the workpiece 10 from the rotary table 9. , Move to the pallet 6, but after the second grinding process at the fifth station 21, any number of subsequent measuring steps and grinding as necessary, such as the third and fourth times It goes without saying that a processing step can be provided. In the subsequent measurement process and the grinding process, for example, the rotary table 9 may be enlarged and the third and fourth measurement processes and the grinding process may be continuously performed. The workpiece 10 is moved through the first station 7 to the second station 8 and the third station 16 again by rotating the rotary table 9 without discharging 10, thereby repeating the subsequent measurement process and grinding process. May be performed.
[0030]
As described above, by executing at least one grinding process and two measurement processes before and after the grinding process, the measurement value B of the hole 11 of the workpiece 10 in the measurement process after the processing is the target dimension A. When it is confirmed that a predetermined number of workpieces are continuously within the predetermined permissible range, the initial adjustment of the cutting amount H is finished, and the cutting amount H at that time is a constant value at the station. And the subsequent processing of the workpiece 10 is continued. Needless to say, since the target dimension A and the cutting depth H are different for each station, the cutting depth H is not set to the same value in all processing steps.
[0031]
FIG. 5 is a schematic diagram illustrating the initial adjustment method of the cutting amount according to the present invention as described above. First, in the control device built in the operation panel 14 or 15 of the grinding machine 1, numerical values a, b, c are read or calculated from a plurality of (n) past processing data accumulated. By executing the first measurement process on the workpiece 10 in the grinding machine 1 and obtaining the measurement value, the air cut amount E is determined and the grinding wheel 18 is moved quickly to the inner surface of the hole 11. Make contact. Then, the dimension A as a target that the measurement value should reach is set, and the grinding amount G required to reach it is calculated, and then grinding is started. Next, the measurement value B is obtained in the second measurement step after the grinding process is executed. Thereby, a difference value D between A and B is calculated. The difference value D indicates the amount of bending of the grinding wheel 18 and the shaft 19. From these values, the calculation formula H = a × (G−c) + (b + D)
The cutting amount H is calculated by the above and fed back to the machining process.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram illustrating a grinding machine as an object to which an initial cutting amount adjustment method of the present invention is applied.
FIG. 2 is a cross-sectional view for explaining a measurement process.
FIG. 3 is a cross-sectional view for explaining a dimensional relationship.
FIG. 4 is a cross-sectional view for explaining a processing step.
FIG. 5 is a block diagram schematically illustrating an initial adjustment method of a cutting amount according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Grinding machine 2 ... Robot 5 ... Conveyor 9 ... Turning table 10 ... Workpiece 11 ... Hole 12 ... Reference pins 14, 15 ... Operation panel 18 ... Grinding wheel 19 ... Shaft

Claims (3)

At least a first measuring step for measuring the inner diameter of the hole in the workpiece before processing, and a processing step for processing the inner surface of the hole so that the measured inner diameter of the hole in the workpiece matches the target dimension; In the hole machining method for sequentially executing the second measurement step of measuring the inner diameter of the hole of the workpiece after machining,
When the machining tool used in the machining process is updated,
A first measuring step of measuring the inner diameter of the hole before processing the first workpiece;
A machining step of calculating a cutting amount of the machining tool based on the target dimension and the first measurement value, positioning the machining tool according to the cutting amount, and executing machining on the first workpiece; ,
A second measuring step of measuring the inner diameter of the hole for the processed first workpiece;
A first measurement step of measuring the inner diameter of the hole before processing the second workpiece;
The cutting depth of the machining tool is calculated based on the target dimension and the first measurement value, and the difference value between the target dimension and the second measurement value of the first workpiece is calculated. Machining that corrects the depth of cut by adding the difference value to the previously calculated depth of cut, positions the machining tool according to the corrected depth of cut, and executes machining on the second workpiece Process,
A second measuring step for measuring the inner diameter of the hole for the processed second workpiece;
As in the case of the second workpiece, the first measurement process, the machining process, and the second measurement process are sequentially performed for the third and subsequent workpieces. When it is confirmed in a predetermined number of workpieces that the measured value of the second time is within the allowable range from the target dimension, the machining tool is positioned so as to maintain the cutting depth at that time. Then, the initial adjustment method of the cutting depth characterized by continuing the subsequent processing of the workpiece. In claim 1, the target dimension is A, the scraping amount required to reach the target dimension A is G, the inner diameter of the hole measured after machining in the preceding workpiece is B, and the difference between the value A and the value B D, the deflection amount per unit load of the machining tool calculated from the accumulated machining data, that is, the deflection rate is a, and b is a correction value determined according to the amount of machining per unit time, which also indicates the sharpness of the machining tool, When the cutting amount is manually determined when the cutting amount is determined by automatic control, the cutting amount H of the machining tool in the machining of the second and subsequent workpieces is calculated by the following equation, where c is the correction value of the cutting amount manually added. A method for initial adjustment of a cutting amount, characterized by positioning a processing tool.
H = a × (G−c) + (b + D) 3. The grinding tool according to claim 1, wherein the machining tool is a grinding wheel that rotates about its own central axis, and the workpiece is also supported so as to rotate about its own central axis. The initial adjustment method of the cutting depth.

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