JP5262440B2 - Grinding machine and grinding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinder capable of inhibiting the formation of a work affected layer at a corner formed between an outer peripheral surface and an end surface of a workpiece even if grinding efficiency is improved. <P>SOLUTION: A wet grinder 10 includes a grinding fluid immersion promoting means 65 for promoting the immersion of a grinding fluid to a contact region Tc of a corner Wc formed between the outer peripheral surface and the end surface Wb of the workpiece in a region T where a grinding surface 25ba formed along an outer periphery of a grindstone 25 and the outer peripheral surface Wa of the workpiece W are in contact, whereby the corner of the workpiece can be fully cooled, formation of the work affected layer on the corner can be inhibited, and the quality of the workpiece can be improved. In addition, since the formation of the work affected layer at the corner of the workpiece can be inhibited, grinding efficiency can be improved and a grinding cycle time can be reduced. Thus, the cost of grinding can be reduced. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a grinding machine and a grinding method for grinding a workpiece with a grindstone while supplying a grinding liquid toward a contact portion between a grinding surface formed on the outer circumference of the grindstone and a peripheral surface of the workpiece. .

  In Patent Literature 1, when grinding is performed by bringing a grindstone into contact with a workpiece, air is blown from a nozzle toward the grinding portion of the workpiece, thereby suppressing generation of a temperature gradient in the grinding portion and reducing thermal distortion. Thus, a dry grinding machine that enables high-precision grinding is disclosed. However, when the work being hardened is ground with high efficiency by increasing the cutting speed of the grindstone with the dry grinding machine, the grinding part may be insufficiently cooled, which occurs at the grinding part. There is a possibility that a work-affected layer is formed by grinding heat. This work-affected layer is called a so-called white layer and is a re-quenched martensite layer. This work-affected layer can generate residual stress on the surface of the workpiece and cause a reduction in the strength of the workpiece.

On the other hand, in Patent Document 2, when grinding is performed by bringing a grindstone into contact with a workpiece, a rough grinding process is performed by adjusting a cutting amount of the grindstone while supplying coolant from a nozzle toward a grinding portion of the workpiece. A wet grinder that performs finish grinding is disclosed. According to this, since the grinding part can be sufficiently cooled even if the workpiece being hardened is ground at a high efficiency by increasing the cutting speed of the grindstone, the work-affected layer in the grinding part can be sufficiently cooled. Formation can be suppressed.
Japanese Patent Laid-Open No. 11-320403 (paragraphs 0009 and 0011, FIG. 3) JP 2007-268664 A (paragraphs 0014, 0015, 0017, 0048, FIG. 4)

  However, even in the wet grinding machine described in Patent Document 2, if the grinding speed is further increased by further increasing the cutting speed of the grindstone, a work-affected layer is formed, and in particular, the outer periphery of the workpiece. There is a large problem at the corner formed by the ground surface and the end surface formed on the surface. The present applicant has renewed the knowledge that the coolant supplied to the corner of the workpiece being hardened is likely to be discharged to the outside of the corner, and cooling of the corner becomes insufficient. I got it. And the present applicant made this invention based on this knowledge.

  An object of the present invention is to provide a grinding machine and a grinding method capable of suppressing the formation of a work-affected layer at a corner formed by an outer peripheral surface and an end surface of a workpiece even when the grinding efficiency is increased.

In order to solve the above-mentioned problem, the structural feature of the invention according to claim 1 is that the grinding fluid is supplied toward the contact portion between the grinding surface formed on the outer periphery of the grindstone and the outer peripheral surface of the workpiece. In a grinding machine that grinds the workpiece with a grindstone, it comprises grinding fluid penetration facilitating means for accelerating the penetration of the grinding fluid into the contact portion of the corner formed by the outer peripheral surface and the end face of the workpiece , The grinding liquid infiltration promoting means includes two films having a length from a position of a supply port of the supply nozzle of the grinding liquid to a position exceeding the contact portion of a corner portion of the workpiece, and the grinding liquid is One end of the two films is attached to the supply port at an interval of the width of the workpiece so as to flow down to the outside of the contact portion at the corner of the workpiece along the back surface of the two films. It is that.

Structural feature of the invention according to claim 2 is the grinding machine according to claim 1, wherein the two films are Ru der that the film gap is configured to be adjustable.

請 structural feature of Motomeko according to 3 invention, grinding the workpiece by the grinding wheel while supplying the grinding fluid toward a contact portion between the outer peripheral surface of the outer peripheral which is formed in the grinding surface of the grinding wheel and the workpiece In the processing method, one end of two films having a length from a position of a supply port of the supply nozzle of the grinding fluid to a position exceeding a contact portion of a corner formed by an outer peripheral surface and an end surface of the workpiece Is attached to the supply port with a gap in the width of the work piece, and the grinding liquid is used to promote the penetration of the grinding liquid into the contact portion of the corner of the work piece. And flow down to the outside of the contact area at the corner of the workpiece along the back surface .

  According to the first aspect of the present invention, in the wet grinder, the corner formed by the outer peripheral surface of the workpiece and the end surface portion of the portion where the ground surface formed on the outer periphery of the grindstone contacts the outer peripheral surface of the workpiece. Since it is equipped with grinding fluid penetration facilitating means that accelerates the penetration of grinding fluid into the contact area of the workpiece, the corner of the workpiece can be sufficiently cooled, and the formation of a work-affected layer at the corner is suppressed. The quality of the workpiece can be improved. Moreover, since formation of the work-affected layer at the corners of the workpiece can be suppressed, the grinding efficiency can be improved, and the grinding cost can be reduced.

The grinding fluid penetration promoting means includes two films having a length from the position of the supply port of the grinding fluid supply nozzle to a position exceeding the contact portion of the corner of the workpiece, and one end of the two films. Are attached to the supply port with a gap in the width of the workpiece, so that when the grinding process is performed, the opposite sides of the two films are the width of the workpiece, and the workpiece is fed from the supply port of the grinding fluid supply nozzle. The space between the contact parts is sandwiched. For this reason, it is possible to promote the penetration of the grinding fluid without letting it escape to the outside particularly at the contact portion of the corner of the workpiece, so that the corner of the workpiece can be sufficiently cooled, and machining at the corner is performed. Formation of the altered layer can be suppressed.

According to the invention of claim 2 , since the two films are configured such that the film interval can be adjusted, it is possible to easily cope with changes in the width of the workpiece, and to improve the grinding efficiency. , Ru it is possible to suppress the grinding cost.

According to the invention of 請 Motomeko 3, when grinding the workpiece by the grinding wheel while supplying the grinding fluid toward a contact portion of the grinding surface formed on the outer periphery of the grinding wheel and the outer peripheral surface of the workpiece, tool Since it accelerates the penetration of the grinding fluid into the contact area of the corner formed by the outer peripheral surface and the end surface of the workpiece, the corner of the workpiece can be sufficiently cooled, and a work-affected layer is formed at the corner. Can improve the quality of the workpiece. Moreover, since formation of the work-affected layer at the corners of the workpiece can be suppressed, the grinding efficiency can be improved, and the grinding cost can be reduced.

  Then, one end of two films having a length from the position of the supply port of the grinding fluid supply nozzle to a position exceeding the contact portion of the corner of the workpiece is attached to the supply port with a gap of the width of the workpiece. Therefore, during grinding, the opposing side surfaces of the two films are sandwiched between the supply port of the grinding fluid supply nozzle and the contact part of the workpiece with the width of the workpiece. For this reason, it is possible to promote the penetration of the grinding fluid without letting it escape to the outside particularly at the contact portion of the corner of the workpiece, so that the corner of the workpiece can be sufficiently cooled, and machining at the corner is performed. Formation of the altered layer can be suppressed.

  FIG. 1 shows the entire grinding machine of this embodiment. A table 12 is guided and supported on a bed 11 of the cylindrical grinding machine 10 so as to be movable in the horizontal Z-axis direction. It is moved in the Z-axis direction via a ball screw. A headstock 15 and a tailstock 16 are arranged on the table 12 so as to face each other, and the workpiece W can be rotated around an axis parallel to the Z-axis direction between the headstock 15 and the tailstock 16. The center is supported. A spindle 18 that is rotationally driven by a spindle drive motor 17 is rotatably supported on the spindle stock 15, and the workpiece W is connected to the spindle 18 via a drive fitting or the like and is driven to rotate.

  On the bed 11, a grindstone table 20 is supported so as to be movable in a horizontal X-axis direction orthogonal to the moving direction of the table 12, and is moved in the X-axis direction by a servo motor 21 via a ball screw. A grinding wheel shaft 22 is supported on the grinding wheel base 20 so as to be rotatable about an axis parallel to the main shaft 18, and is rotationally driven by a grinding wheel driving motor 23 via a belt transmission mechanism. A grindstone 25 having a grinding surface 25ba formed on the outer periphery is attached to the tip of the grindstone shaft 22. The grinding wheel base 20 is provided with an AE sensor 26 that detects elastic waves generated by contact between the grinding wheel 25 and the workpiece W or the truing roll 30.

  The grindstone 25 is a grindstone for grinding an outer peripheral cylindrical surface that grinds the cylindrical outer peripheral surface Wa of the workpiece W. The grindstone 25 has a configuration in which a grindstone layer 25b having an annular cross section in the radial direction is formed on the outer periphery of a disk-shaped metal or CFRP core 25a. The grindstone layer 25b is formed, for example, by sticking a plurality of grindstone chips having a circular cross section in the radial direction formed by bonding CBN abrasive grains, which are superabrasive grains, with vitrified bonds to the outer peripheral surface of the core 25a. . The grindstone 25 having such a configuration is rotated at a high speed, and the outer peripheral surface Wa of the workpiece W is ground by the grinding surface 25ba of the grindstone layer 25b.

  The coolant supply device 60 is provided with coolant (grinding) toward a grinding portion where the grindstone 25 grinds the workpiece W, that is, a contact portion T (see FIG. 5) between the grinding surface 25ba of the grindstone 25 and the outer peripheral surface Wa of the workpiece W. Supply). The coolant supply device 60 includes a coolant supply nozzle 61, a pump 62, a motor 63, a coolant storage tank 64, two films (grinding fluid infiltration promoting means) 65, and the like. The coolant supplied from the pump 62 driven by the motor 63 is controlled in flow rate by a flow control valve (not shown), and is contacted from the supply port 61a of the coolant supply nozzle 61 attached to the grindstone cover (not shown) above the grindstone 25. Supplied to site T to cool and lubricate. The coolant supplied to the contact portion T flows below the bed 11, and after the chips are separated by a magnet separator (not shown), the coolant is returned to the coolant storage tank 64 again. Here, the two films 65 serve as grinding fluid infiltration promoting means for accelerating the penetration of the coolant into the contact portion Tc (see FIG. 5) of the corner portion Wc formed by the outer peripheral surface Wa and the end surface portion Wb of the workpiece W. The function will be described later.

  A truing unit 31 that is rotatably provided with a truing roll 30 for truing the grindstone 25 is disposed on the side surface of the headstock 15 on the grindstone table 20 side. The truing unit 31 includes a housing 33 attached to the headstock 15, a truer shaft 34 disposed in the housing 33 so as to be rotatable around a horizontal axis parallel to the grindstone 25, and a built-in motor 32 that rotationally drives the truer shaft 34. A thin truing roll 30 for truing the grindstone 25 is attached to the tip of the truer shaft 34.

  The CNC device 51 for controlling the grinding machine 10 mainly comprises a central processing unit 52, a memory 53 for storing various control values and programs, and interfaces 54 and 55. The memory 53 stores various data necessary for executing a grinding cycle and a truing cycle, such as a grinding processing program, a truing program, contact detection position data, truing incision amount data, grinding wheel diameter data, and grinding wheel width data. Has been. Various data are input to the CNC device 51 via an input device 56. The input device 56 includes a keyboard for inputting data and a display device such as a CRT for displaying data. It has. Further, a detection signal from the AE sensor 26 is input to the CNC device 51 via an amplifier 59.

  The CNC device 51 gives a drive signal to the X-axis servomotor 21 that moves the grindstone table 20 in the X-axis direction via the X-axis motor drive unit 57 and also moves the table 12 to the Z-axis via the Z-axis motor drive unit 58. A drive signal is given to the Z-axis servomotor 13 that moves in the direction. Further, the CNC device 51 counts the number of workpieces W processed by the grindstone 25, and instructs the start of a truing operation when the number of workpieces reaches a predetermined value.

  Here, FIG. 2A is a cross-sectional photograph of the vicinity of the outer peripheral surface of the workpiece ground by the dry grinder, and FIG. 2B is the outer peripheral surface of the workpiece ground by the wet grinder. FIG. 5C is a cross-sectional photograph of the vicinity of the outer peripheral surface of the workpiece that has been ground by a wet grinder with both ends of the workpiece covered with epoxy resin. Grinding conditions are as follows: Coolant: None for dry grinders, Epoxy resin covering both end faces of the work part: None, Grinding efficiency: 3, and Coolant supply amount: 30 liters / for wet grinders min, epoxy resin covering both end faces of the machine part: None, grinding efficiency: 20, and in the case of a wet type grinding machine (both end faces of the work part are coated with epoxy resin), coolant: 30 l / min, both ends of the machine part Epoxy resin covering the surface: Yes, with a grinding efficiency of 20. These cross-sectional photographs are obtained by cutting a workpiece in the radial direction, polishing the cross-section, and performing etching.

  As a result, as shown in the relationship diagram between the work-affected layer depth and the position in the workpiece width direction in FIG. 3, in the case of a dry grinder, the depth is 60 μm to 70 μm over the entire workpiece width direction as shown by the solid line. In the case of a wet grinder without an epoxy resin coating on both end faces of the work part, the width direction is 0 mm to 30 mm at the left corner of the workpiece and the width direction is at the right corner, as shown by the alternate long and short dash line. A work-affected layer that linearly decreases from a maximum depth of 70 μm over 80 mm to 65 mm was formed. However, in the case of a wet grinding machine having an epoxy resin coating on both end faces of the work part, a work-affected layer was not formed over the entire work width direction as shown in the figure. Further, as shown in the relationship diagram between the Vickers hardness of FIG. 4 and the depth from the end of the outer peripheral surface Wa of the workpiece W (hereinafter referred to as the outer peripheral surface Wa end), both ends of the work part are coated with epoxy resin. In the case of a non-wet grinder, the Vickers hardness is 450 Hv to 600 Hv at a depth of 100 μm from the end of the outer peripheral surface Wa as shown by the diamond-shaped points, whereas the wet part has an epoxy resin coating on both end faces of the machined part. In the case of this grinder, the Vickers hardness is improved to 550 Hv to 650 Hv at a depth of 100 μm from the end of the outer peripheral surface Wa as indicated by a triangular point.

  The reason for this is that by covering both ends of the workpiece with epoxy resin, the workpiece is ground by the grindstone while supplying the grinding fluid toward the contact area between the grinding surface formed on the outer circumference of the grindstone and the outer circumferential surface of the workpiece. When grinding, it is possible to promote the penetration of the grinding fluid into the contact portion of the corner formed by the outer peripheral surface and the end surface of the workpiece, so that the corner of the workpiece can be sufficiently cooled, This is thought to be because the formation of a work-affected layer at such corners can be suppressed. Since the corner of the workpiece can be sufficiently cooled in this manner, the quality of the workpiece can be improved by suppressing the formation of a work-affected layer at the corner. In addition, since the formation of a work-affected layer at the corner of the workpiece can be suppressed, the grinding efficiency can be improved, the spark-out time can be shortened, the grinding cycle time can be shortened, and the grinding cost can be reduced.

  From the above results, in the cylindrical grinding machine 10 of the present embodiment, as shown in the side view and the top view of FIGS. Two films 65 are provided as means for promoting the penetration of the coolant into the contact portion Tc of the corner portion Wc formed with the portion Wb. That is, the two films 65 are tapes having a length from a supply port 61a opened in a band shape of the coolant supply nozzle 61 with a resin such as polyethylene to a position slightly exceeding the contact portion Tc of the corner Wc of the workpiece W. It is formed in a shape. The two films 65 are arranged in parallel and their upper ends are slidably attached to the upper wall of the supply port 61a along the width direction (Z-axis direction).

That is, the two films 65 are configured such that the film interval can be freely adjusted, and the two films 65 are arranged so as to sandwich the both end face portions Wb of the workpiece W at the time of grinding. As a result, the coolant supplied from the supply port 61 a of the coolant supply nozzle 61 flows between the two films 65 and flows down to the contact portion T of the workpiece W, and along the back surface of the two films 65. It flows down to the outside of the contact portion Tc of the corner Wc of the object W. Therefore, the coolant flowing down to the outside of the contact portion Tc of the corner Wc of the workpiece W becomes a wall, and the coolant does not escape to the outside at the contact portion Tc of the corner Wc of the workpiece W. Since the penetration can be promoted, the corner portion Wc of the workpiece W can be sufficiently cooled, and the formation of a work-affected layer at the corner portion Wc can be suppressed. Two films 65 may be arranged in parallel, and the upper end may be attached to the lower wall of the supply port 61a so as to be slidable along the width direction (Z-axis direction). Thus, the opposing side surfaces of the two films 65 become walls to promote the penetration of the coolant into the contact portion Tc without letting the coolant escape to the outside at the contact portion Tc of the corner portion Wc of the workpiece W. it can. The thickness of the film 65 is about 1mm is not good from the standpoint of handling.

In the above embodiment, the film 65 is mounted on the cylindrical grinder 10, but the present invention can also be applied to a cam grinder, a plank pin grinder, and the like.

It is a figure which shows the whole grinding machine of this Embodiment. (A) is a cross-sectional photograph of the vicinity of the outer peripheral surface of a workpiece ground by a dry grinder, (B) is a cross-sectional photograph of the vicinity of the outer peripheral surface of a workpiece ground by a wet grinder, (C ) Is a cross-sectional photograph of the vicinity of the outer peripheral surface of a work piece that is covered with an epoxy resin and ground by a wet grinding machine. 3 is a graph showing a relationship between a work-affected layer depth and a workpiece width direction position in FIGS. It is a graph which shows the relationship between the Vickers hardness in FIG. 2 (B), (C), and the depth from the outer peripheral surface Wa edge part. (A), (B), the Ru side view and a top view showing one embodiment of a grinding fluid penetration promoting means provided in the grinding machine of FIG.

DESCRIPTION OF SYMBOLS 10 ... Cylindrical grinder, 20 ... Grinding wheel base, 25 ... Grinding wheel, 25b ... Grinding wheel layer, 25ba ... Grinding surface, W ... Workpiece, Wa ... Outer circumference of workpiece Surface, Wb ... End surface of workpiece, Wc ... Corner of workpiece, BW ... Width of workpiece, T ... Contact part, Tc ... Contact part of corner Wc, 61. ... coolant supply nozzle, 61a ··· supply port, 65 ... fill-time.

Claims (3)

In a grinding machine that grinds the workpiece with the grindstone while supplying a grinding liquid toward the contact portion between the grinding surface formed on the outer circumference of the grindstone and the outer circumferential surface of the workpiece,
Grinding liquid infiltration accelerating means for accelerating the infiltration of the grinding liquid into the contact portion of the corner formed by the outer peripheral surface and the end surface of the workpiece ,
The grinding fluid penetration promoting means includes two films having a length from the position of the supply port of the grinding fluid supply nozzle to a position exceeding the contact portion of the corner of the workpiece,
One end of the two films is spaced from the supply port at the width of the workpiece so that the grinding fluid flows down the back of the two films to the outside of the contact portion at the corner of the workpiece. A grinder characterized by being mounted with a gap. 2. The grinding machine according to claim 1 , wherein the two films are configured such that a film interval can be adjusted. In the method of grinding the workpiece by the grindstone while supplying a grinding liquid toward the contact portion between the grinding surface formed on the outer circumference of the grindstone and the outer circumferential surface of the workpiece,
One end of two films having a length from the position of the supply port of the supply nozzle of the grinding fluid to a position exceeding the contact site at the corner formed by the outer peripheral surface and the end surface of the workpiece is defined as the supply port. With a gap in the width of the workpiece,
In order to promote the penetration of the grinding fluid into the contact portion of the corner portion of the workpiece, the grinding fluid is placed outside the contact portion of the corner portion of the workpiece along the back surface of the two films. A grinding method characterized by flowing down .

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