JP2005034963A - Grinding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding device capable of further improving the surface roughness of works. <P>SOLUTION: This grinding device 10 has a work rotational driving unit 20 for rotatingly driving a crankshaft 50 as a work W having a working surface 51, a grinding wheel rotational driving unit 30 for rotatingly driving a grinding wheel 31 having an abrasive grain surface 32, and an oscillation unit 40 for imparting oscillation in the axial direction of the work to at least one of the work and the grinding wheel. Grinding work is performed while relatively oscillating the working surface of the work and the abrasive grain surface of the grinding wheel. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a grinding apparatus for grinding a work surface of a workpiece with a grindstone.

  When grinding a workpiece having a processed surface, a grinding apparatus for grinding the processed surface with an abrasive surface of a grindstone is widely used (see, for example, Patent Documents 1 to 3).

  Generally, a grindstone in a grinding apparatus has a disk shape, and an abrasive grain surface is formed on a surface in a direction parallel to the rotation axis direction, that is, an outer peripheral surface. Then, the outer peripheral abrasive grain surface of the rotating grindstone is pressed against the processing surface of the rotating workpiece to grind the processing surface.

  There are two types of grinding methods: a plunge grinding method that presses the abrasive surface of the grindstone against the work surface of the workpiece, and a traverse grinding method that moves the workpiece in the axial direction as in the case of grinding a long workpiece. .

  In the plunge grinding method, in order to press the grindstone against the work, the uneven shape of the abrasive grain surface is transferred as it is onto the work surface of the work. For this reason, there is a problem in that it is difficult to improve the surface roughness because the grinding streaks remain on the work surface of the work in a direction orthogonal to the axial direction of the work.

On the other hand, the traverse grinding method can improve the surface roughness as compared with the plunge grinding method because the grindstone and the workpiece relatively move in the axial direction. However, since a screw lead-shaped grinding streak remains on the work surface of the workpiece, there is a limit to the improvement of the surface roughness.
Japanese Patent Laid-Open No. 10-44031 JP-A-6-246629 JP-A-5-42477

  The present invention has been made to solve the problems associated with the above-described conventional technology, and an object thereof is to provide a grinding apparatus capable of further improving the surface roughness.

  The object of the present invention is achieved by the following means.

The present invention comprises a workpiece rotation driving means for rotating a workpiece having a machining surface,
Grinding wheel rotation drive means for rotationally driving a grinding wheel having an abrasive surface;
Oscillation means for providing oscillation along the axial direction of the workpiece to at least one of the workpiece and the grindstone,
It is a grinding device that performs grinding while relatively oscillating the processing surface of the workpiece and the abrasive surface of the grindstone.

  The grinding device according to the present invention produces an effect that the surface roughness of the processed surface can be further improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a grinding apparatus 10 according to an embodiment of the present invention, FIG. 2 is a diagram showing a main part of the grinding apparatus 10, and FIG. 3 (A) is a grain size and average abrasive grains of a grindstone 31. A chart showing an example of the interval L, FIG. 3 (B) is a diagram for explaining the average abrasive grain interval L of the grindstone 31, and FIG. 3 (C) is a conceptual diagram showing grinding processing in the present embodiment, FIG. (D) is a conceptual diagram which shows the grinding process by the plunge grinding method which concerns on a proportional. FIG. 4 is a diagram illustrating an example of the crankshaft 50 as the workpiece W to be ground. For convenience of explanation, the axial direction of the crankshaft 50 (left-right direction in FIG. 1) is defined as the X direction, and the horizontal direction orthogonal to the X direction (direction orthogonal to the paper surface in FIG. 1) is defined as the Y direction. The vertical direction (vertical direction in FIG. 1) perpendicular to the X direction is defined as the Z direction.

  The grinding apparatus 10 of this embodiment will be outlined with reference to FIGS. 1 and 2. A work rotation drive unit 20 (corresponding to the work rotation drive means 20) that rotationally drives a work W having a machining surface 51, an abrasive Oscillation along the axial direction of the workpiece W is imparted to at least one of the workpiece W and the grinding wheel 31 and a grinding wheel rotation drive unit 30 (corresponding to the grinding wheel rotation driving means 30) that rotationally drives the grinding wheel 31 having the grain surface 32. And an oscillation unit 40 (corresponding to the oscillation means 40). Then, the grinding process is performed while relatively oscillating the machining surface 51 of the workpiece W and the abrasive grain surface 32 of the grindstone 31.

  The workpiece W in the present embodiment includes a protruding portion that protrudes radially outward at at least one end portion along the axial direction of the processed surface 51. As this type of workpiece W, a crankshaft 50 can be cited as shown in FIG. 4, and the outer peripheral surfaces of the journal portion 52 and the pin portion 53 of the crankshaft 50 become a processing surface 51 on which grinding is performed. Further, the flange portion 54 protruding outward in the radial direction corresponds to the protruding portion.

  Hereinafter, the grinding device 10 will be described in detail.

  Referring to FIG. 1, the work rotation drive unit 20 includes a headstock 22 that rotatably supports a main shaft 21, a chuck 23 that is connected to the tip of the main shaft 21 and grips one end of a crankshaft 50, and a main shaft 21. It has a spindle motor M1 connected via a belt 24, and a tailstock 26 having a center 25 that supports the other end of the crankshaft 50. The crankshaft 50 is driven to rotate by transmitting the rotational movement of the main shaft motor M <b> 1 via the belt 24 and the main shaft 21. Each of the head stock 22 and the tail stock 26 is provided on tables 27 and 28 that are slidable along the Y direction. The tables 27 and 28 are arranged on a table 29 that is slidable along the X direction. ing. In order to set the crankshaft 50 between the head stock 22 and the tailstock 26, or to move the crankshaft 50 to the machining position, the tables 27, 28, 29 are moved.

  Referring to FIG. 2, the grindstone 31 has a disk shape, and an abrasive grain surface 32 is formed on the outer peripheral surface. Examples of the abrasive grains include aluminum oxide, silicon carbide, diamond, and the like. The particle size of the abrasive grains is appropriately selected according to the surface properties (surface roughness) required for the processed surface 51. For example, as shown in FIG. 3A, a grindstone 31 having a particle size # 140 (average particle size 107 μm) to a particle size # 60 (average particle size 252 μm) is used. Note that FIG. 3A is merely an example of the grindstone 31 used, and does not limit the grindstone 31 used in the present invention.

  The grindstone 31 differs in the average abrasive grain interval L (see FIG. 3B) of the abrasive grains 33 depending on the grain size and the degree of abrasive grain concentration. In the grindstone 31 in the range shown in FIG. 3 (A), the average abrasive grain interval L is 107 μm (grain size # 140 (average grain size 107 μm), when the abrasive grain concentration is 200) to 1008 μm (grain size # 60 (average). Particle diameter 252 μm) and the abrasive concentration is 50). “When the abrasive grain concentration is 200” means that the abrasive grains 33 are put in the maximum and the abrasive grains 33 are adhered to each other. The actual grindstone 31 has an abrasive grain ratio of 50%. Many of them have an abrasive concentration of about 100. In addition, the average abrasive grain interval L is a calculated value, and the actual abrasive grain interval L varies somewhat.

  Referring to FIG. 2, the grindstone rotation drive unit 30 includes a spindle 35 connected on a rotation shaft 34 of the grindstone 31, and a grindstone motor M <b> 2 that rotates the spindle 35. The spindle 35 is disposed in parallel with the axis O of the crankshaft 50. The grindstone rotation drive unit 30 is disposed on a grindstone table (not shown) that is slidable along the X and Y directions, and the position of the spindle can be adjusted along the Z direction. The position of the grindstone 31 is adjusted by adjusting and moving the grindstone table in the X and Y directions and adjusting the position of the spindle in the Z direction.

  Referring to FIG. 1, the oscillation unit 40 includes an eccentric rotator 41 that abuts the end surface of the table 29, and an oscillation motor M <b> 3 that rotationally drives the eccentric rotator 41. The oscillation unit 40 includes elastic means 42 such as a spring that biases the elastic force that presses the table 29 toward the eccentric rotator 41 so that the end surface of the table 29 and the eccentric rotator 41 are always in contact with each other. Is provided. The oscillation amplitude is determined based on the amount of eccentricity of the eccentric rotating body 41 with respect to the axis of the oscillation motor M3. For example, when the amount of eccentricity is set to about 0.5 mm, the amplitude of oscillation is about 1 mm, and when the amount of eccentricity is set to about 1 mm, the amplitude of oscillation is about 2 mm. The amount of eccentricity of the eccentric rotating body 41 can be adjusted by a known means such as changing the number of inserted adjustment plates (not shown).

  It is preferable that the oscillation width, that is, the amplitude provided by the oscillation unit 40 is equal to or greater than the average abrasive grain interval L of the grindstone 31 to be used. If the width of the oscillation is set to be equal to or greater than the average abrasive interval L of the grindstone 31, the convex portion 55 (FIG. 3) that remains on the processed surface 51 when the uneven shape of the abrasive surface 32 is transferred to the processed surface 51. This is because (see (D)) can be removed by the relative movement of the individual abrasive grains 33. In the grindstone 31 in the range shown in FIG. 3 (A), even if there is some variation in the actual average grain interval L, if the oscillation width is set to 1 mm (1000 μm) or more, individual Due to the relative movement of the abrasive grains 33, it is possible to remove the convex portions 55 that will remain on the processed surface 51.

  Furthermore, the number of cycles per unit time of the oscillation given by the oscillation unit 40, that is, the oscillation speed depends on the workpiece shape, the basic grinding conditions (workpiece rotation speed and wheel rotation speed), the required surface roughness, etc. Since it is determined, it is not uniquely determined, but it is realistic to select between 100 to 900 cycles / minute, and a sufficient effect can be obtained within this range.

  The controller 60 controls the operation of each motor M1, M2, M3. By changing the rotational speed of the spindle motor M1, the workpiece rotational speed Vw is set to a desired speed, and by changing the rotational speed of the grinding wheel motor M2, the grinding wheel rotational speed Vg is set to a desired speed. By changing the rotation speed of the motor M3, the oscillation speed Vo is set to a desired speed. The controller 60 also controls the operation of a motor group (not shown) for moving the positions of the grindstone table, the tables 27, 28, 29 and the spindle 35.

  Next, the operation of this embodiment will be described.

  First, the crankshaft 50 is supported between the headstock 22 and the tailstock 26. The grindstone rotation drive unit 30 is moved so that the abrasive grain surface 32 contacts the processed surface 51 of the journal portion 52 or the pin portion 53.

  While the oscillation motor M3 of the oscillation unit 40 gives the crankshaft 50 oscillation in the axial direction, the spindle motor M1 of the work rotation drive unit 20 rotates the crankshaft 50 about the axis, thereby rotating the grindstone rotation drive unit. The grindstone 31 is rotated by 30 grindstone motor M2.

  The amplitude of the oscillation to be applied is set to be larger than the average abrasive grain interval L of the grindstone 31, for example, 1 mm (1000 μm). The oscillation speed Vo is set to 100 to 900 cycles / minute.

  Then, when the rotating grindstone 31 is pressed against the crankshaft 50 that is rotated and given oscillation, the processing surface 51 and the abrasive surface 32 are relatively oscillated while the processing surface 51 is caused by the abrasive surface 32. Grinded.

  When the grinding process for the plurality of journal portions 52 or pin portions 53 included in the crankshaft 50 is completed, the grindstone rotation drive unit 30 is moved backward so that the crankshaft 50 can be taken out. If another crankshaft 50 is set after taking out the crankshaft 50, the same grinding process can be started.

  As shown in FIG. 3 (D), when the grinding is performed by the plunge grinding method, the uneven shape of the abrasive grain surface is directly transferred to the processed surface 56 of the workpiece W, and the convex portion 55 is formed on the processed surface 56. Will remain. For this reason, grinding streaks remain on the machining surface 56 in a direction perpendicular to the axial direction of the workpiece W, and it is difficult to improve the surface roughness. In order to increase the surface roughness, it is conceivable to use abrasive grains having a small average particle diameter. However, in this case, clogging of the grindstone is likely to occur, and there is a possibility that sharpness is reduced and grinding burn is caused.

  On the other hand, in the grinding apparatus 10 according to the present embodiment, as indicated by an arrow in FIG. 3C, the crankshaft 50 is given oscillation along the axial direction. The trajectory of the grains 33 is relatively shifted in the left-right direction in the figure. Due to the relative movement of the abrasive grains 33, the convex portions 55 that remain on the processed surface 51 when the shape of the abrasive grain surface 32 is transferred are removed. Moreover, the grinding streaks that are formed along with the grinding process are not screw-leaded as in the case of the traverse grinding method, but wave-shaped grinding streaks drawn by the individual abrasive grains 33 overlap each other to form a cross hatch. It becomes. As a result, the surface roughness of the processed surface 51 such as the journal portion 52 and the pin portion 53 is remarkably improved.

  On both sides of the journal portion 52 and the pin portion 53 of the crankshaft 50, there are flange portions 54 and the like. The flange portion 54 becomes an obstacle that collides with the grindstone 31 when the workpiece W is traversed. For this reason, the traverse grinding method cannot be performed, and conventionally, plunge grinding has to be performed, and improvement in surface roughness has been hindered. Even in such a case, in the grinding apparatus 10 of the present embodiment, since the oscillation along the axial direction is given to the crankshaft 50, even if the traverse grinding method cannot be performed, the journal portion 52 is provided. In addition, the surface roughness of the pin portion 53 can be easily improved.

  Furthermore, since the oscillation amplitude is set to, for example, 1 mm (1000 μm) which is equal to or greater than the average abrasive grain interval L of the grindstone 31, the convex portion 55 is reliably removed. In addition, the cross-hatched grinding streak becomes finer. Therefore, the processed surface 51 is formed with finer surface roughness.

  In addition, in order to make a grinding stripe into a cross hatch shape in the grinding process, it is necessary to run the abrasive grains 33 obliquely on the processed surface 51 and to provide oblique grinding striations. For this purpose, it is necessary that the abrasive grains 33 continue to contact the processing surface 51 for a certain period of time and the length of the chips is about 0.5 to 3 mm. In the case of general grinding conditions, the chip length is the above length, but when the abrasive grain cutting amount is extremely shallow, the peripheral speed of the workpiece W is extremely slow, or extremely fast, The chip length is not the above length.

  The peripheral speed of the workpiece W during grinding is set to a peripheral speed ratio of about 1/50 to 1/200 of the peripheral speed of the grindstone 31, generally about 1 (work W) / 100 (grindstone 31). . For example, when the peripheral speed of the grindstone 31 is 3000 m / min, the peripheral speed of the workpiece W is set to 30 m / min.

  Under such grinding conditions, the workpiece W and the grindstone 31 are relatively oscillated in the axial direction of the workpiece W so that the grinding striations are inclined. In order to increase the inclination angle of the grinding stripe, the number of cycles per unit time of oscillation, that is, the oscillation speed Vo, should be fast, and should be selected between 100 to 900 cycles / min. From the viewpoint of shortening the grinding time by increasing the number of working abrasive grains per unit time on the work surface 51, the oscillation speed Vo is preferably high.

  Further, if the oscillation speed Vo is the same, the oscillation amplitude should be as large as possible in order to increase the inclination angle of the grinding stripe. Although there is no upper limit to the oscillation amplitude, if the workpiece W or the grindstone 31 is to be oscillated at a high speed in the axial direction, the equipment for the oscillation becomes large and the equipment cost increases. End up. Therefore, it is realistic to set the oscillation amplitude to about 1 mm to 2 mm or less.

  The oscillation unit 40 for adding oscillation of about 1 mm to 2 mm and amplitude of 100 to 900 cycles / min is widely applied to machining devices and the like. If this technology is used, the equipment cost will not increase.

  As described above, according to the grinding apparatus 10 of the above-described embodiment, the workpiece rotation driving unit 20 that rotationally drives the workpiece W having the processed surface 51 and the grindstone rotation that rotationally drives the grindstone 31 having the abrasive grain surface 32. The drive unit 30 and an oscillation unit 40 that imparts oscillation to the workpiece W along the axial direction of the workpiece W. The machining surface 51 of the workpiece W and the abrasive grain surface 32 of the grindstone 31 are relatively oscillated. Since the grinding process is performed, the convex portion 55 that remains on the processing surface 51 when the shape of the abrasive grain surface 32 is transferred is removed by the relative movement of the abrasive grains 33. The grinding streaks formed in this manner are cross-hatched by overlapping the grinding streaks drawn by the individual abrasive grains 33 with each other. As a result, the surface roughness of the processed surface 51 can be further improved.

  Moreover, since the width of the oscillation along the axial direction of the workpiece W provided by the oscillation unit 40 is equal to or greater than the average abrasive grain interval L of the grindstone 31, the convex portion 55 is surely removed, and the cross hatch shape is obtained. The grinding streaks of this will be finer. Therefore, the processed surface 51 can be formed with finer surface roughness.

  Further, since the number of cycles per unit time of the oscillation along the axial direction of the workpiece W provided by the oscillation unit 40 is 100 to 900 cycles / minute, the equipment cost related to the oscillation unit 40 may increase. Absent.

  In addition, the workpiece W includes a protruding portion that protrudes outward in the radial direction at at least one end portion along the axial direction of the processing surface 51, and the traverse because the grindstone 31 collides with the protruding portion. Even when the grinding method cannot be performed, the surface roughness of the processed surface 51 can be improved.

  Further, the work surface 51 of the workpiece W is a journal portion 52 or a pin portion 53 of the crankshaft 50. Even when these processing surfaces 51 include flange portions 54 and the like that protrude radially outward, and the grinding wheel 31 collides with the flange portions 54 and the like, the traverse grinding method cannot be performed. The surface roughness of the journal part 52 and the pin part 53 can be easily improved.

(Modification example)
The workpiece W and its processed surface 51 are not limited to a cylindrical outer peripheral surface having a perfect circle cross section like the journal portion 52 and the pin portion 53 of the crankshaft 50. Needless to say, the present invention can also be applied to a grinding apparatus that grinds an arc-shaped machining surface having a non-circular cross section, such as a cam lobe portion of a camshaft, or an inner circumferential machining surface of a cylindrical body.

  Although the grindstone 31 having the abrasive grain surface 32 on the outer peripheral surface has been illustrated, a grindstone having an abrasive grain surface formed on a plane perpendicular to the rotation axis can also be used.

  Although the grindstone rotation drive unit 30 is shown in which the grindstone 31 is directly driven to rotate by the grindstone motor M2, the rotation shaft 34 of the grindstone 31 and the grindstone motor M2 may be connected via a belt.

  In the illustrated oscillation unit 40, the oscillation is given to the table 29 and the workpiece W is given the oscillation. However, the oscillation may be given to the main shaft 21 that supports the workpiece W. Moreover, it is not restricted to giving an oscillation to the workpiece | work W, You may give an oscillation to the grindstone 31, or you may give an oscillation to both the workpiece | work W and the grindstone 31. FIG. The mechanism for generating oscillation is not limited to that using the eccentric rotating body 41, and for example, an ultrasonic vibrator may be used.

  The width of the oscillation can be determined in relation to the average abrasive grain interval L of the grindstone 31 to be used, and does not always have to be set to 1 mm (1000 μm) or more. For example, in the case of using the grindstone 31 having the particle size # 140 (average particle size 107 μm) exemplified in FIG. 3A and the abrasive concentration 100, the oscillation width may be set to 214 μm or more. . Furthermore, when using a grindstone other than the grindstone 31 illustrated in FIG. 3A, the oscillation width may be set to be equal to or greater than the average abrasive grain interval L of the grindstone used.

  Oscillation can be further added to the transverse grinding method.

  Conventionally, the term “grinding” refers to roughing, and the term “polishing” refers to finishing. However, the grinding apparatus 10 according to the present invention selects roughening by selecting the grain size of the grindstone 31. It can be applied to both processing and finishing. In this respect, the term “grinding” in the present specification should be understood as a concept including not only roughing but also “polishing” which conventionally refers to finishing.

  The grinding apparatus can be applied to a purpose of grinding a work surface of a workpiece with a grindstone.

It is a schematic structure figure showing a grinding device concerning an embodiment of the present invention. It is a figure which shows the principal part of a grinding device. 3A is a chart showing an example of the grindstone particle size and average abrasive grain spacing, FIG. 3B is a diagram for explaining the average abrasive grain spacing of the grindstone, and FIG. 3C is the present embodiment. FIG. 3D is a conceptual diagram showing grinding in a plunge grinding method according to the proportional method. It is a figure which shows an example of the crankshaft as a workpiece | work which is ground.

Explanation of symbols

10 grinding equipment,
20 Work rotation drive unit (work rotation drive means),
21 spindle,
30 grinding wheel rotation drive unit (grinding wheel rotation drive means),
31 Whetstone,
32 Abrasive surface,
40 Oscillation unit (oscillation means),
41 Eccentric rotating body,
50 crankshaft,
51 machined surface,
52 Journal part,
53 pin part,
54 Flange (projection),
L Average abrasive spacing,
M1 spindle motor,
M2 grinding wheel motor,
M3 oscillation motor,
W Work.

Claims (5)

A workpiece rotation driving means for rotating and driving a workpiece having a machining surface;
Grinding wheel rotation drive means for rotationally driving a grinding wheel having an abrasive surface;
Oscillation means for providing oscillation along the axial direction of the workpiece to at least one of the workpiece and the grindstone,
A grinding apparatus that performs grinding while relatively oscillating the processed surface of the workpiece and the abrasive surface of the grindstone.   The grinding apparatus according to claim 1, wherein the oscillation width along the axial direction of the workpiece provided by the oscillation means is equal to or greater than an average abrasive grain interval of the grindstone.   The grinding apparatus according to claim 1, wherein the number of cycles per unit time of oscillation along the axial direction of the workpiece provided by the oscillation means is 100 to 900 cycles / minute.   The grinding apparatus according to claim 1, wherein the workpiece includes a protruding portion protruding radially outward at at least one end portion along the axial direction on the processing surface.   The grinding apparatus according to claim 1, wherein the machining surface of the workpiece is a journal portion or a pin portion of a crankshaft.

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