JP2013071204A - Rigidity measuring method and grinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rigidity measuring method capable of measuring the accurate deflection of the grinding portion of a workpiece during grinding to measure accurate grinding position rigidity using the measuring result and grinding resistance, and to provide a grinder.SOLUTION: A starting position diameter D, which is a diameter including a measuring starting position A being the position of the face of a processing part positioned at a place at an angle smaller than 180° in the rotation direction of a grinding acting position, is measured. When the measuring starting position A reaches a position facing the grinding acting position in relation to a rotation axis center O of the workpiece W, a surface distance L which is a distance of a straight line connecting rotation center at both axis ends of the workpiece to the measuring starting position A, and a normal grinding resistance force R acting at this time are simultaneously measured. After measuring the starting position diameter D, a finishing position diameter D, which is the diameter including the measuring starting position A when the workpiece W has rotated by 180° is measured. The grinding position rigidity k which is rigidity at the grinding acting position of the workpiece W is calculated by using an equation: k=R/(L-(D+D)/4).

Description

  The present invention relates to a rigidity measuring method and a grinding machine for measuring the rigidity of a workpiece during grinding.

In the grinding machine, in order to grind the workpiece with high accuracy and high efficiency, the cutting speed and the cutting amount of the grinding wheel are controlled in consideration of the deflection amount due to the grinding resistance of the workpiece. . In order to predict the amount of deflection, it is only necessary to measure the rigidity and grinding resistance of the grinding part of the workpiece. The grinding resistance can be easily measured during grinding by measuring the current of the feed motor and providing a load sensor.
On the other hand, regarding the measurement of rigidity, in a grinder equipped with an AE sensor that determines whether or not grinding is performed, the grinding resistance at the time of grinding at a predetermined grinding wheel cutting position is measured, and the grinding wheel is not ground from this position. Assuming that the amount of retreat is the deflection of the workpiece at this time, the rigidity is obtained by calculation using the previous grinding resistance and this deflection (for example, see Patent Document 1).

JP 2008-93787 A

  In the prior art, it is necessary to retract the grindstone during grinding in measuring the deflection, and the grinding time becomes long. Further, since grinding is continued even during retreat, an error corresponding to a decrease in radius due to the grinding is added to the deflection.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a grinding machine capable of measuring an accurate deflection of a grinding portion during grinding and measuring an accurate rigidity by using this and a grinding resistance. .

In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that the grinding part is ground while using a grinding machine for rotating and supporting a cylindrical workpiece and cutting a grinding wheel into the workpiece. In the rigidity measurement method for measuring the rigidity of the machined part,
A start diameter measuring step of measuring a start position diameter D ₀ which is a diameter including a measurement start position which is a position of a surface of the processed portion located less than 180 degrees in the rotation direction from the grinding action position;
When the measurement start position reaches a position opposite to the grinding action position with reference to the rotation axis of the workpiece, a distance of a straight line connecting the rotation centers at both shaft end portions of the workpiece with respect to the measurement start position. A distance / resistance measuring step for simultaneously measuring a certain surface distance L and a normal grinding resistance R acting at this time;
An end diameter measuring step of measuring the end point diameter D ₂ is the diameter that includes a measurement start position when the workpiece from the measurement the starting position the diameter D ₀ is rotated 180 degrees,
A rigidity calculating step of calculating a grinding position rigidity k, which is a rigidity at the grinding action position of the workpiece, using an equation k = R / (L− (D ₀ + D ₂ ) / 4).

A feature of the invention according to claim 2 is a grinding machine for rotating and supporting a cylindrical workpiece and grinding a processing portion by a grinding wheel.
A workpiece diameter measuring device for measuring the outer diameter of the processed part;
A position measuring device for measuring the position of the surface of the processed part in the cutting direction of the grinding wheel;
A normal resistance measuring device for measuring normal resistance during grinding;
A start position diameter D ₀ which is a diameter including a measurement start position of the machining portion located less than 180 degrees in the rotation direction from the grinding action position measured by the workpiece diameter measuring device;
When the measurement start position reaches a position facing the grinding action position with reference to the rotation axis of the workpiece, the surface position of the measurement start position measured by the position measuring device and the shaft end of the workpiece A surface distance L which is the distance of the rotational support center position, and a normal grinding resistance R acting at this time, which is simultaneously measured by the normal resistance measuring device,
And end diameter D ₂ workpiece after measuring the starting position the diameter D ₀ of measurement is a diameter including a measurement start position when rotated 180 degrees by the workpiece diameter measuring device,
It is to a control device for calculating a grinding position stiffness k of the workpiece using the formula _{k = R / (L- (D} 0 + D 2) / 4).

According to the first aspect of the present invention, using the start position diameter D ₀ and the end position diameter D ₂ measured during grinding, the surface distance L, and the normal grinding resistance force R acting at this time, By calculating the rigidity k, the rigidity of the processed part can be measured in a short time during grinding.

According to the second aspect of the present invention, the processed portion is measured by using the start position diameter D ₀ and the end position diameter D ₂ measured during grinding, the surface distance L, and the normal grinding resistance R acting at this time. By calculating the rigidity k, it is possible to realize a grinding machine capable of measuring the rigidity of the processed part in a short time during grinding.

It is the schematic which shows the whole structure of the grinding machine of this embodiment. It is a B arrow line view of FIG. It is a conceptual diagram which shows the measuring method of this embodiment. It is a flowchart which shows the rigidity measurement process of this embodiment. It is a figure which shows the rigidity measurement process of this embodiment.

Hereinafter, an embodiment of the present invention will be described based on examples of a cylindrical grinding machine with reference to FIGS.
As shown in FIG. 1, the cylindrical grinding machine 1 includes a bed 2, supported on the bed 2 so as to be reciprocable in the X-axis direction and driven by a feed motor 9, and a Z-axis orthogonal to the X-axis. A table 4 capable of reciprocating in the direction is provided. The grinding wheel base 3 rotatably supports the grinding wheel 7, and the grinding wheel 7 is rotationally driven by a grinding wheel shaft rotating motor (not shown). On the table 4, a spindle 5 provided with a phase detector 10 that grips one end of the workpiece W and rotatably supports it and is rotationally driven by a spindle motor (not shown) to detect the rotational phase of the spindle; A tailstock 6 that rotatably supports the other end of the workpiece W is provided. The workpiece W is supported by the main shaft 5 and the tailstock 6 and is rotationally driven during grinding. A measuring device 8 for measuring the processed part of the workpiece W is installed on the table.
As shown in FIG. 2, the measuring device 8 is disposed so as to face the workpiece diameter measuring device main body 831 held by the base 81 fixed to the table and the workpiece diameter measuring device main body 831 at 180 degrees. A workpiece diameter measuring device 83 composed of contacts 832a and 832b and a bracket 82 held on the base 81 are fixed to a bracket 82 to measure the surface position of the workpiece W opposed to the grinding action position by 180 degrees. A capacitance type surface position measuring device 85 is provided. The contacts 832a and 832b and the surface position measuring device 85 are arranged at the same position in the axial direction of the workpiece W and with a phase difference of Φ in the rotation direction, and can measure the same portion of the processing portion.

  The grinding machine 1 includes a control device 30. As a functional configuration of the control device 30, an X-axis control unit 31 that controls the feed of the grindstone table 3, a Z-axis control unit 32 that controls the feed of the table 4, a spindle 5 includes a spindle control unit 33 that controls the rotation of 5, a measurement device control unit 34 that controls the measurement device 8, a calculation unit 35 that incorporates a recording unit 351 and calculates rigidity. As a function of the X-axis control unit 31, a normal grinding resistance measurement unit 311 that measures a normal grinding resistance force acting on the grinding wheel 7 during grinding from a current value of the feed motor 9 is provided.

The measurement of the grinding position rigidity will be described with reference to FIG. 3 showing a cross section perpendicular to the axis of the workpiece W at the machining position.
In FIG. 3, a position at a machining position of a line connecting the rotation center of the spindle 5 and the center center of the tailstock 6 which is the rotation reference of the workpiece W is defined as a point P. When normal grinding resistance acts on the workpiece W, the rotation center of the processed portion is a point O that is moved from the point P by deflection. Assuming that the distance between the surface A of the processing part located in the opposite direction of the grinding action part on the straight line connecting the point P and the point O and the point P is L, and the radius from the point O to the surface A of the processing part is r ₁ The distance (deflection amount) t ₁ between the point P and the point O is expressed as t ₁ = L−r ₁ . If the grinding resistance in the normal direction acting on the workpiece at this time is R ₁ , the rigidity k at the grinding position of the workpiece can be calculated by k = R ₁ / t ₁ = R ₁ / (L−r ₁ ).

Here, assuming that the diameter including the current grinding operation position and the surface A is D ₂ and the diameter including the surface A before one rotation is D ₀ , D ₀ = r ₁ + r ₀ , D ₂ = r ₁ + r ₂ Become. In the steady grinding state in which the grinding removal speed is constant, the reduction speed of the workpiece diameter is constant, and the grinding of the surface A is performed before ½ rotation, so r ₁ is an intermediate between r ₀ and r ₂ . Because of the size, r ₁ = (r ₀ + r ₂ ) / 2. From the above formula, r ₁ = (D ₀ −r ₁ + D ₂ −r ₁ ) / 2 holds, and from this, r ₁ = (D ₀ + D ₂ ) / 4. The measurement of D ₀ is performed when the surface A is at the position of the contactor 832b at the past time point when the workpiece W is rotated back by the angle Φ from the position shown in FIG. Measurements of D ₂ is the workpiece W from the position shown in FIG. 3 at the time of after rotating by an angle (180-Φ), the surface A is measured when in the position of the contact 832a.
From the above, the rigidity k can be calculated by k = R ₁ / t ₁ = R ₁ / (L−r ₁ ) = R ₁ / (L− (D ₀ + D ₂ ) / 4).

The distance L between the point P and the surface A of the processed part is L = u−, where u is the distance between the point P and the surface position measuring device 85 and s ₁ is the distance between the surface A of the processed part and the surface position measuring device 85. s ₁ and u is a constant value determined by the arrangement of the measuring device 8, the main shaft 5, and the tailstock 6.
From the above, the rigidity k is R ₁ measured by the normal grinding resistance measuring unit 311, s ₁ measured by the surface position measuring device 85, D ₀ and D ₂ measured by the workpiece diameter measuring device 83, and the equation k = R _{1 / (u-s 1 - (} D 0 + D 2) / 4) can be calculated using.

The process of measuring the rigidity during grinding in the grinding machine 1 will be described with reference to the flowchart of FIG. 4 and FIG.
First, the point P, which is the position at the machining position of the line connecting the rotation center of the spindle 5 and the center center of the tailstock 6 and the distance u between the surface position measuring device 85 is recorded in the recording unit 351 (S1). In the steady grinding state, D ₀ is measured by the workpiece diameter measuring device 83 and recorded in the recording unit 351. As shown in FIG. 5A, the position of the surface A of the workpiece that the contact 832b contacts at the time of measurement is set as the measurement start position (S2). The main axis is rotated by Φ degrees until the surface A reaches the position of the surface position measuring device 85 (S3). As shown in FIG. 5B, the distance s ₁ between the surface A and the surface position measuring device 85 is measured by the surface position measuring device 85, and simultaneously the normal grinding resistance R ₁ is measured by the normal resistance measuring unit 311. Recording is performed in the recording unit 351 (S4). The main shaft is rotated by (180−Φ) degrees until the surface A reaches the position of the contact 832a (S5). As shown in FIG. 5 (c), the workpiece diameter _{D 2} of the position where the surface A is in contact with the contact 832a is measured and recorded in the recording unit 351 (S6). The workpiece rigidity k is calculated by the calculation unit 35 using the formula k = R ₁ / (us−s ₁ − (D ₀ + D ₂ ) / 4).

  As described above, when the rigidity measuring method of the present invention is used, the rigidity at the grinding position of the workpiece can be measured during grinding, and the grinding amount, the grinding feed speed, and the like can be set using the rigidity value. Since there is no need for special rigidity measurement time, the grinding time can be shortened.

In the above example, the current value of the grindstone feed motor 9 is detected and the normal grinding resistance is measured. However, a load measuring sensor may be installed on the spindle stock 5 and the tailstock 6 for measurement.
Although the non-contact type surface position measuring device 85 is used, a contact type measuring machine such as a differential transformer type may be used.
Although the rigidity measurement was performed during steady grinding where the grinding removal speed is constant, the rigidity may be measured with the grinding wheel cutting speed constant. Furthermore, even if the cutting speed of the grinding wheel fluctuates, if the fluctuation range is small, rigidity measurement may be performed.

W: Workpiece 3: Whetstone base 4: Table 5: Spindle 6: Tailstock 7: Grinding wheel 8: Measuring device 9: Whetstone feed motor 30: Control device 35: Calculation unit 85: Surface position measuring device 832a, 832b : Contact

Claims (2)

In a rigidity measurement method for measuring the rigidity of the processed part while grinding the processed part using a grinding machine that rotates and supports a cylindrical workpiece and cuts the grinding wheel into the workpiece,
A start diameter measuring step of measuring a start position diameter D ₀ which is a diameter including a measurement start position which is a position of a surface of the processed portion located less than 180 degrees in the rotation direction from the grinding action position;
When the measurement start position reaches a position opposite to the grinding action position with reference to the rotation axis of the workpiece, a distance of a straight line connecting the rotation centers at both shaft end portions of the workpiece with respect to the measurement start position. A distance / resistance measuring step for simultaneously measuring a certain surface distance L and a normal grinding resistance R acting at this time;
An end diameter measuring step of measuring the end point diameter D ₂ is the diameter that includes a measurement start position when the workpiece from the measurement the starting position the diameter D ₀ is rotated 180 degrees,
A stiffness measurement method comprising a stiffness calculation step of calculating a grinding position stiffness k, which is a stiffness at a grinding action position of the workpiece, using an equation k = R / (L− (D ₀ + D ₂ ) / 4). In a grinding machine that rotationally supports a cylindrical workpiece and grinds a processing part with a grinding wheel,
A workpiece diameter measuring device for measuring the outer diameter of the processed part;
A position measuring device for measuring the position of the surface of the processed part in the cutting direction of the grinding wheel;
A normal resistance measuring device for measuring normal resistance during grinding;
A start position diameter D ₀ which is a diameter including a measurement start position of the machining portion located less than 180 degrees in the rotation direction from the grinding action position measured by the workpiece diameter measuring device;
When the measurement start position reaches a position facing the grinding action position with reference to the rotation axis of the workpiece, the surface position of the measurement start position measured by the position measuring device and the shaft end of the workpiece A surface distance L which is the distance of the rotational support center position, and a normal grinding resistance R acting at this time, which is simultaneously measured by the normal resistance measuring device,
And end diameter D ₂ workpiece after measuring the starting position the diameter D ₀ of measurement is a diameter including a measurement start position when rotated 180 degrees by the workpiece diameter measuring device,
A grinding machine provided with a control device for calculating a grinding position rigidity k of a workpiece using an expression k = R / (L− (D ₀ + D ₂ ) / 4).

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