TWI600494B - Variable speed grinding method for making mills - Google Patents

Description

Variable speed grinding method for tools

This creation is about a variable speed grinding method for a tool, especially for adjusting the grinding wheel speed during the grinding to make a correction, thereby completing a more precise blade lead curve.

As shown in Fig. 1, it is known that the grinding of the cutter 20 is performed by grinding the grinding wheel 10 of the grinder to remove unnecessary portions of the cutter 20. The shape, size and angle of the grinding wheel 10 are accurate or not, and the machining precision and the machining speed are both direct. The impact is also growing in importance. The cutter 20 of the drawing, such as a milling cutter, has a general end face of 2 or 4 blades, and has different cutter performances of the number of cutting edges. The 2 blades are larger than the 4-blade cutting groove, so that there is good chip removal, but the 2 blades are cut off due to the cutting edge. The smaller the area, the lower the rigidity of the tool itself, the easier it is to bend in the case of heavy milling, and the poor milling surface, which also has an adverse effect on the machining accuracy. The 4-blade has poor cutting performance. Due to the large cross-sectional area of the tool, good rigidity can be obtained. Generally, the processed surface roughness can be obtained. The helix angle is an indispensable factor for reducing vibration during cutting and increasing cutting sharpness. Usually the tool 20 using a helix angle [theta] between about 15 and 60 designed to degrees θ =. End of the helix angle θ of about 15 degrees keyway cutter for machining lines, about 30 degrees helix angle θ general standard processing, about 45 degrees with a helical coil having both standard strong helix end mill, can be used The scope is wider.

In general, the tool 20 should form a correct lead curve 22 after grinding by the grinding wheel 10. However, there are many factors that affect the grinding of the tool 20, such as the rotational speed of the grinding wheel 10, the abrasive, the particle size, the hardness, and the like. When the grinding wheel 10 is grinding, the phenomenon of grain passivation, surface blockage and edge deformation of the abrasive will occur, which will affect the grinding efficiency and precision. If the cross-sectional shape of the ground tool 20 is enlarged and observed, it will be slightly elliptical, triangular or irregular. In the grinding process, a certain temperature rise occurs in the processing zone of the tool 20 and its adjacent area due to the heat of cutting, and the surface layer has a high temperature during the grinding process, and the surface layer of the tool 20 when the temperature reaches the critical point of the phase change. Metals undergo metallographic changes, strength and hardness are reduced, residual stresses are generated, and even microscopic cracks occur. This phenomenon is called grinding burns. Another important factor is that the axial deformation caused by the pressing force of the grinding wheel 10 during the grinding of the tool 20 causes a deviation of the lead curve 24 on the blade portion 21 of the tool 20 (as shown in Fig. 2). On the other hand, a deviation distance β is formed with the correct lead curve 22, which causes a defect in the accuracy of the cutting edge of the tool 20, which affects the processing quality of the cutting operation with the periphery of the tool 20 in the future.

The invention provides a variable speed grinding method for a tool, which is characterized in that different grinding wheel speeds produce different grinding lead curves when grinding by a tool, and the rotation speed of the grinding wheel is changed by adjusting a control point of the second Bezier curve. Controlling to generate different grinding lead curves, the steps comprising: generating an image file for the previously ground tool; selecting one of the tool outer diameters on the image file as the P0 point; For the effective cutting depth of the tool, one of the cutting edge points of the tool outer diameter is selected as the P2 point; on the image file, according to the cutting edge along the P0 point to the P2 point, a cutting point is selected as the P1 point to be ground. deviation distance correction control point; and defining a [alpha] in the blade portion to be polished of the blade length, P0 point and the point P2 are respectively located at two ends of blade length [alpha] of, and define a △ α to be polished trace edge length and defining a beta] being a cutting edge portion of the wide variation distance and define a △ β is the blade edge portion of the width of trace offset distances, and defines a d the tool edge diameter, and defines a C α to be polished of Micro blade The length coefficient, the value range of C α is between 0.005 and 0.01, and the definition of a C β is the micro-deviation distance coefficient of the blade width of the blade, and the value of C β ranges from 0.001 to 0.005; the rotation speed set to the P0 point is RPMA, set the rotation speed to P2 point to RPMC, and define a RPMB to rotate the P1 point, and define a t to indicate that the P1 point is in a unit to be polished edge length α , starting from the P0 point to the P2 point. For the location of the end point, 0 t 1, and the number of bits after the decimal point of t defines a micro-grinding aliquot of the unit to be polished edge length α ; according to the quadratic Bezier curve formula B(t)=(1-t) ² P0+2t(1- t)P1+t ² P2,0 t 1. Recalculate the blade grinding lead curve until B(t) approximates the correct edge grinding lead curve; when B(t) approximates the correct edge grinding lead curve, the position of the P1 point is measured by the measuring instrument. The amount, and the Δ α and Δ β which are ground to the point P1 here, wherein Δ α =d×C α , Δ β =d×C β ; the rotation speed to the P1 point RPMB is determined according to the value of Δ α or Δ β And the grinding wheel speed is based on the RPMA, RPMB, and RPMC value substituted into the variable grinding speed formula VAG(t)=(1-t) ² RPMA+2t(1-t)RPMB+t ² RPMC,0 t 1, that is, the P0 point in the formula B(t) of the second Bezier curve is correspondingly adjusted to the rotational speed RPMA of the P0 point, the P1 point corresponding to the rotational speed RPMB adjusted to the P1 point, and the P2 point correspondingly adjusted to the rotational speed RPMC of the P2 point, and The secondary Bezier curve formula is converted into a variable grinding speed formula VAG(t) for variability grinding to correct the lead curve of the deviation.

The invention has the characteristics of the variable speed grinding method of the cutter, that is, the difference value of the deviation lead curve is obtained by using the Bezier curve, and the deviation of the lead curve is corrected by moving the P1 point, and the system utilizes two. The principle of the sub-Bezie curve is changed to the variation rule of the rotation speed of the grinding wheel. Different grinding wheel rotation speeds produce different grinding lead curves when the tool is ground. Adjustment via variation value △ α and △ β quadratic Bézier curve P1 is the change of the grinding wheel speed to do quadratic Bézier curve based on the values generated, to correct the deviation of the lead curve, this method is primarily changes in grinding Adjust the grinding wheel speed to make corrections and complete a more accurate lead curve.

10‧‧‧ Grinding wheel

20‧‧‧Tools

21‧‧‧Knife

22‧‧‧correct lead curve

23‧‧‧ Approximate correct lead curve

24‧‧‧ Deviation lead curve

X _W , Y _W , Z _W ‧‧‧ indicate the three axial directions of the grinding wheel in space

X _t , Y _t , Z _t ‧‧‧ respectively represent the three axial directions of the milling cutter in space

D‧‧‧ is the tool radius

P0 point ‧‧‧ is the sharp point of the blade

P1 point ‧‧‧ is the control point

P2 point ‧‧‧ is the blade point

T‧‧‧ indicates that P1 is in the unit to be polished edge length α , from the point where P0 is the origin to the position where P2 is the end point, 0 t 1

α ‧‧‧ is the length of the blade to be ground

△ α ‧‧‧ is the minimum blade length to be ground (△ α =d×C α )

C α ‧‧‧ is the minimum blade length coefficient to be ground, and the value of C α ranges from 0.005 to 0.01

β ‧‧‧ is the deviation distance of the blade width of the blade

△ β ‧‧‧ is the slight deviation distance of the blade width of the blade (△ β = d × C β )

C β ‧‧‧ is the micro-deviation distance coefficient of the blade width of the blade, and the value of C β ranges from 0.001 to 0.005

The speed of the RPMA‧‧‧ grinding wheel at the point P0 of the cutting edge

The speed of the RPMB‧‧‧ grinding wheel at the control point P1

The speed of the RPMC‧‧‧ grinding wheel at the cutting point P2

Figure 1 Schematic diagram of the grinding wheel grinding tool.

Figure 2 shows a schematic diagram of the lead curve for the outer diameter deviation after the tool has been ground.

Figure 3 shows that a unit blade length α, a blade cusp point P0, a blade point P2 are defined on the image file of the ground tool sample, and that a control point P1 is defined on the lead curve of the deviation, And a schematic diagram of the deviation distance β of the blade width at the blade portion.

Figure 4 shows a schematic diagram of the approximately correct lead profile after the tool has been ground by the method of the present invention.

Fig. 5 is a view showing the variation of the blade width at the blade length of each portion when the grinding wheel rotational speed value and the grinding wheel are fixed rotational speed values in accordance with the method of the present invention.

All of the following drawings are merely illustrative of the basic teachings of the present invention, and the extension of the number, position, relationship, and size of the components constituting the preferred embodiments will be explained in the drawings. Post-guided changes are implemented in industry skills. In addition, after reading and understanding the guidance of the present invention, it is also an industry skill to change the size ratios of the number of divisions, the amount of deviation, the number of rotations, and the like.

In the different drawings, the same reference numerals are used to designate the same or similar elements. In addition, please understand that the texts such as "front", "back", "end", "side", and the like are only convenient for the viewer to refer to the figure. The constructions are only used to help describe the invention.

According to the schematic display, the present invention proposes a variable-speed grinding method for a tool, which uses different tool rotation speeds to produce different characteristics of the grinding lead curve when the tool is ground, and adjusts the control point of the second Bezier curve. A variation control of the rotational speed of the grinding wheel is generated to produce different grinding lead curves. In order to describe the machining position of the tool 20 in detail for the method of the present invention, a P0 point is defined as one of the cutting edge points of the cutting edge portion 21 of the tool 20, and a P2 point is defined as one of the blade portions 21 of the tool 20. The blade point, and a point P1, are defined as at least one blade point selected along the blade portion 21 from point P0 to point P2 as a control point (as shown in Fig. 3).

Of the present invention the tool is variable speed polishing method, defined a [alpha] on the blade portion 21 to be polished of the blade length, P0 point and the point P2 are respectively located at two ends of blade length [alpha] of, and define a △ α to be polished trace blade length, and definition of a beta] being a cutting edge portion of the wide variation distance and define a △ β is the blade edge portion of the width of trace offset distances, and defines a d the tool edge diameter, and defines a C α is The micro-blade length coefficient to be polished, C α ranges from 0.005 to 0.01, and defines a C β as the micro-deviation distance coefficient of the blade width of the blade, and the value of C β ranges from 0.001 to 0.005.

Since the deviation distance β of the blade width 21 is very fine (generally between 0.001 mm and 0.5 mm), in order to facilitate the description of the method of the present invention, at least one P1 point is taken as an illustrative example in FIG. 3, and the P1 point located in the middle of the edge length α to be polished, and thus the present invention the method comprises the step of, prior to the milling tool 20 generates an image file, may be JPEG, BMP, or other known image file format of the access to the image After the file reading program opens the image file, one of the outer diameters of the tool 20 can be selected as the P0 point on the outer diameter of the tool 20, and then the outer diameter of the tool 20 is selected according to the depth of the effective tool 20 on the image file. One of the cutting edge portions 21 has a cutting point of P2, and on the image file, a cutting point is selected as the control point of the deviation distance to be grounded according to the cutting edge portion 21 along the P0 point to the P2 point. And set the rotation speed to P0 point to RPMA, set the rotation speed to P2 point to RPMC, and define a RPMB to rotate the P1 point, and define a t to indicate that the P1 point is in a unit to be polished edge length α , The P0 point is the origin from the origin to the position where the P2 point is the end point, 0 t 1, and the number of bits after the decimal point of t defines a micro-grinding aliquot of the unit length α to be polished.

According to the quadratic Bezier curve formula: B(t)=(1-t) ² P0+2t(1-t)P1+t ² P2,0 t 1. Recalculate the lead curve 24 of the deviation after the blade is ground until B(t) approximates that the blade is ground to the correct lead curve 23. In the quadratic Bezier curve formula B(t) used in the method of the present invention, t is a position in which the P1 point is in a unit to be polished edge length α , from the point where the P0 point is the origin to the point where the P2 point is the end point. The t/ α system shown in the figure indicates the length of the P1 point from the P0 point in 1 unit α . For example, if t=0.5, it means that the P1 point is located at 0.5 unit to be polished edge length α from the point P0. That is, the position of the edge of the edge to be polished α , and a number of digits after the decimal point of t, which means that the division is 10 equal parts in the unit length α to be polished. For example, if t=0.05, it means that the P1 point is located at 0.05 unit to be polished edge length α from the point P0, and there are two digits after the decimal point of t, which means that it is divided into 100 in a unit to be polished edge length α . Minute.

And, when B (t) approximates the correct blade grinding lead curve i.e. measuring instrument for detecting the amount of change in the position of point P1 22 and set by the mill ground to a computer program obtains the point P1 where △ α And Δ β , where Δ α = d × C α , Δ β = d × C β . For example, the tool edge diameter d=12mm, C α is taken as 0.008, C β is taken as 0.003, and Δ α =d×C α =12×0.008=0.096(mm) is obtained, and Δβ =d×C β =12×0.003 is obtained. = 0.036 (mm). In the method of the invention, the value of C α ranges from 0.005 to 0.01, and the value of C β ranges from 0.001 to 0.005. The principle of the coefficient is based on the size of the tool edge d to be ground, and is set in the computer program. The larger the cutting edge diameter d is, the larger the values of C α and C β are taken in the numerical range. Conversely, the smaller the cutting edge diameter d is, the larger the values of C α and C β are taken in the numerical range.

The method of the present invention, the speed variation is obtained of the position of the point P1, may be milled to the point P1 is calculated in accordance with the rotational speed RPMB △ α or △ β values are summarized below, and a selection from the following four equations selected as RPMB = K × RPMA (1-△ α / α ) or RPMB = K × RPMA (1-△ β / β ), or RPMB = K × RPMC (1-△ α / α ), or RPMB = K × RPMC (1 Δ β / β ), where K is the correction factor, and the range of values of the correction factor K can be defined as 0.7 to 0.9 depending on the difference in the blade diameter or material properties of the tool to be ground. In the above four calculation formulas, the first two refer to the rotation speed of P0 point, the latter two refer to the rotation speed of P2 point, the first and the third refer to the tangential position variation of P1 point to P0 point and P2 point, the second and fourth reference The unevenness of the blade grinding lead curve.

The method of the present invention, or according △ α △ β value calculation formula to four grinding point P1 of the rotation speed RPMB choose a determined speed of RPMB point P1, therefore, the wheel speed variation according to RPMA, RPMB, and substitutes the value RPMC Formula for rotational speed of grinding: VAG(t)=(1-t) ² RPMA+2t(1-t)RPMB+t ² RPMC,0 t 1, to do the variability grinding to correct the lead curve of the deviation. After the tool 20 is ground by the method of the present invention, an approximately correct lead curve 23 as shown in Fig. 4 can be exhibited.

In the method of the invention, the rotational speed formula VAG(t) of the variable grinding is converted into the variation law of the grinding wheel rotation speed according to the principle of the second Bezier curve, that is, the P0 point in the formula B(t) of the second Bezier curve is adjusted to P0. The rotational speeds of the points RPMA and P1 are adjusted to the rotational speed RPMB of the P1 point, and the P2 point is adjusted to the rotational speed RPMC of the P2 point, and the secondary Bezier curve formula is converted into the rotational grinding formula VAG(t) of the variable grinding, that is, VAG(t)=(1-t) ² RPMA+2t(1-t)RPMB+t ² RPMC,0 t 1. If the selected P2 point does not have the deviation of the grinding lead curve, that is, the selected P2 point does not have the deviation of the lead curve, then the point rotation speed of the RPMC can be equivalent to the rotation speed to the P0 point is RPMA, otherwise, If the selected P2 point already has a deviation of the grinding lead curve, the point rotation speed of the RPMC can be set to be different from the grinding speed to the P0 point as RPMA to generate a partial correction of the grinding lead curve.

According to the invention, the variable speed grinding method of the tool is tested in practice, that is, the difference between the variable speed of the method of the invention and the general fixed speed grinding can be understood (as shown in FIG. 5), and the comparison of the test is performed by using a tool. The shank diameter is 12 mm, the blade length is 55 mm, the number of blades is 3, and the helix angle is 45 degrees. Through the variable speed grinding method of the method of the present invention, the blade width variation value after grinding at a blade length of 20 mm is -27%, and the blade width variation value of the fixed rotation speed at 20 mm is +60%, and after grinding at a blade length of 30 mm. The blade width variation value is +3%, which is better than the fixed speed rotation blade blade width variation value of +113% at 30 mm, and the blade width variation value at the blade length of 40 mm is +3%, which is better than the fixed rotation speed of 40 mm. The blade width variation value is +58%, and the blade width variation value at the blade length of 50 mm is +0%, which is better than the blade width variation value of +58% at the fixed rotation speed of 40 mm.

The invention provides a VSG (Variable Speed Grinding) method for obtaining a difference value of a deviation lead curve by using a Bezier curve, and correcting by moving the P1 point. The deviation of the lead curve and the change of the rotation speed of the grinding wheel by the principle of the second Bezier curve produce different grinding lead curves for different grinding wheel rotation speeds during tool grinding. And the amounts of adjustment via variation of P1 quadratic Bézier curve △ α and △ β, so that the grinding wheel speed to do based on the fluctuating value of the secondary Bézier curve generated, to correct the deviation of the lead curve, this method is primarily grinding Timely adjust the wheel speed to make corrections and complete a more accurate lead curve.

The invention disclosed in the specification is intended to be illustrative, and not restrict The scope of the present invention is covered by the attached patent application. All changes to the meaning and scope of the claims are intended to be included within the scope of the invention.

20 tool 21 blade section 22 correct lead curve 23 approximate correct lead curve 24 deviation of the lead curve P0 point is the blade tip point P1 point is the control point P2 point is the blade point t indicates P1 point in a unit to be polished edge In the length α, from the point where the P0 point is the origin to the position where the point P2 is the end point, 0 ≤ t ≤ 1 α is the length of the blade to be ground △ α is the edge length of the blade to be polished β is the edge of the blade The wide deviation distance Δβ is the slight deviation distance of the blade width of the blade

Claims (6)

A variable-speed grinding method for a tool, wherein when the tool is ground, different grinding wheel speeds produce different characteristics of the grinding lead curve, and by adjusting the control point of the secondary Bezi curve, the variation control of the grinding wheel speed is generated, Producing different grinding lead curves, the steps comprising: generating an image file for the previously ground tool; selecting one of the tool outer diameters on the image file as the P0 point; and cutting the effective tool according to the image file Deep, select one of the cutting edge points of the tool outer diameter as the P2 point; on the image file, according to the cutting edge along the P0 point to the P2 point, select a cutting point as the P1 point as the deviation distance correction to be ground. a control point; and defining an α on the blade portion as the blade length to be polished, P0 point and P2 point respectively at the two ends of the blade length α, and defining a Δα as the minimum blade length to be polished, and defining A β is the deviation distance of the blade width of the blade portion, and defines a Δβ as a small deviation distance of the blade width of the blade portion, and defines a d as the tool edge diameter, and defines a Cα as a micro blade length coefficient to be polished. , C The value range is from 0.005 to 0.01, and a Cβ is defined as the micro-deviation distance coefficient of the blade width of the blade. The value of Cβ ranges from 0.001 to 0.005. The rotation speed set to P0 is RPMA, and the grinding is set to P2. The rotational speed is RPMC, and a RPMB is defined as the rotational speed of the grinding P1 point, and a t is defined to indicate that the P1 point is in a unit to be ground edge length α, and the position from the origin of the P0 point to the end point of the P2 point is 0 ≤ t ≤ 1, and the number of bits after the decimal point of t defines a micro-grinding aliquot of the unit to be polished edge length α; according to the quadratic Bezier curve formula B(t) = (1 - t) ² P0 + 2t(1-t) P1 + t ² P2,0 ≤ t ≤ 1, recalculate the blade grinding lead curve until B(t) approximates the correct edge grinding lead curve; when B(t) approximates the correct cutting edge When grinding the lead curve, the amount of change of the position of the P1 point is measured by the measuring instrument, and Δα and Δβ which are ground to the point P1 here are obtained, wherein Δα=d × Cα, Δβ= d × Cβ; The value of Δα or Δβ determines the rotational speed RPMB ground to the point P1, and the rotational speed of the grinding wheel is substituted into the variable grinding according to the RPMA, RPMB, and RPMC values. Speed formula VAG (t) = (1 - t) 2 RPMA + 2t (1 - t) RPMB + t 2 RPMC, 0 ≤ t ≤ 1, the polishing properties do change, to correct the deviation of the lead curve. The variable speed grinding method for the tool according to the first aspect of the patent application, wherein the method of calculating the grinding speed to the P1 point rotation speed RPMB according to the aforementioned Δα value is RPMB = K × RPMA (1 - Δα / α), wherein K is the correction factor, and the range of K is defined as 0.7 to 0.9. The variable speed grinding method for the tool according to the first aspect of the patent application, wherein the method of calculating the grinding speed to the P1 point rotation speed RPMB according to the aforementioned Δβ value is RPMB = K × RPMA (1 - Δβ / β), wherein K is the correction factor, and the range of K is defined as 0.7 to 0.9. The variable speed grinding method for the tool according to the first aspect of the patent application, wherein the method of calculating the grinding speed to the P1 point rotation speed RPMB according to the aforementioned Δα value is RPMB = K × RPMC (1 - Δα / α), wherein K is the correction factor, and the range of K is defined as 0.7 to 0.9. The variable speed grinding method for the tool according to the first aspect of the patent application, wherein the method of calculating the grinding speed to the P1 point rotation speed RPMB according to the aforementioned Δβ value is RPMB = K × RPMC (1 - Δβ / β), wherein K is the correction factor, and the range of K is defined as 0.7 to 0.9. The variable speed grinding method for the tool according to the first aspect of the patent application, wherein setting the rotation speed to the P2 point to RPMC is equivalent to the rotation speed to the P0 point is RPMA.