JP2016080501A - Method for measuring effective diameter of workpiece in-process constituting screw shaft, and measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a workpiece effective diameter in-process measurement method and measurement device with which it is possible to stably support the workpiece that constitutes a screw shaft even when polishing pressure from a grindstone is large and improve the dimensional accuracy of the formed screw shaft.SOLUTION: An effective diameter in-process measurement device comprises a probe 13 contactably disposed in the screw groove of a workpiece 11 that constitutes a screw shaft opposite a machining point by a grinding wheel 7, a mono-axis table 17 for positioning the probe 13 and connected to a grindstone base 9, two sets of parallel plate springs connected to the mono-axis table 17 so as to be able to elastically displace the probe 13 in the axial and radial directions of the workpiece 11, and an arithmetic processing device 99 for calculating a correction amount for the depth of cut-in to the workpiece 11 by the grinding wheel 7 on the basis of the displacement of the probe 13. The measurement device is provided with a plurality of shake stopping devices 67 disposed below the workpiece 11 on a table 5 that supports the workpiece 11 and support the workpiece 11 to a groove 89 in a shape of a V-shaped cross section by a magnetic attraction force.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an in-process measurement method and a measurement apparatus for a workpiece when grinding a workpiece which becomes a screw shaft of a ball screw device.

  Ball screw devices are used as machine elements such as machine tools, semiconductor manufacturing devices, compression molding machines, injection molding machines, and general conveying devices. High accuracy is required for a ball screw device used in such a machine. The screw shaft, which is the main component of the ball screw device, has a thread groove formed by multiple grinding operations. In the grinding of the thread groove of the workpiece that becomes the screw shaft, grinding wheel wear, thermal displacement, mechanical vibration, etc. Therefore, it is difficult to finish the cylindrical shape of the thread groove after forming to 1 μm or less. Therefore, in order to increase the dimensional accuracy of the threaded shaft after forming, the diameter of the workpiece being ground is measured and controlled in-process. In other words, the effective diameter of the workpiece formed with the thread groove is measured in-process. In the precision ball screw, if the cylindricality of the thread groove is insufficient, the preload dynamic torque of the ball screw may be affected. For this reason, the target value of finishing accuracy is set to a small value to improve the grinding accuracy.

In Patent Document 1, a measuring element is connected to and integrated with a workpiece grinding tool, that is, a grinding wheel support base, which is a workpiece screw shaft, and the workpiece is ground on the side opposite to the workpiece machining point. The probe is brought into contact with the thread groove, the workpiece is sandwiched between the grinding wheel and the probe, and the workpiece is detected to detect the radial displacement of the workpiece while moving the workpiece in the axial direction along with the shaft rotation operation. An in-process measurement method and a measurement apparatus for controlling the cutting amount of a grinding wheel are described.
According to the in-process measurement method or the measurement apparatus described in Patent Document 1, the structure is simple and the space is restricted because the contactor is merely brought into contact with the position of the workpiece 180 ° opposite to the machining tool. Can be reduced.

In Patent Document 2, a work and a dummy work are fixed to a magnet chuck on a table of a surface grinder, and after the dummy work is slightly ground by a grinding wheel, an air nozzle in a measurement head unit attached to a grindstone cover is provided as a constituent element. Measure the upper surface position of the dummy workpiece and the upper surface position of the unground workpiece with an air micrometer to determine the level difference between the dummy workpiece and the workpiece, and check the display on the air micrometer to check the necessary allowance for the level difference. A grinding amount control method and a measuring instrument are described in which the grinding wheel is fed by the amount of the amount added and the workpiece is ground by fixing the grinding wheel at that position.
According to the grinding amount control method and the measuring instrument described in Patent Document 2, it is possible to accurately grind even if the necessary machining allowance is 1 μm.

Japanese Patent No. 2905531 Japanese Patent Laid-Open No. 10-315129

  However, Patent Document 1 does not describe a method for supporting a workpiece when the grinding pressure from the grinding wheel is large. That is, in Patent Document 1, when the grinding pressure from the grinding wheel is large, the workpiece may be shaken by being pushed by the grinding wheel. If it does so, the precision of the shape | molded screw shaft will fall. In addition, Patent Document 2 describes a method for supporting a workpiece that is surface ground, but does not describe a method for supporting a workpiece in which a thread groove is ground.

  The present invention has been made in view of such a situation. Even if the grinding pressure from the grindstone is large, the workpiece which is the screw shaft is stably supported to prevent the workpiece from being shaken, and the screw shaft after the molding is formed. An object of the present invention is to provide an effective diameter in-process measurement method and an effective diameter in-process measurement apparatus for a workpiece that becomes a screw shaft capable of improving dimensional accuracy.

  In order to achieve the above object, an effective diameter in-process measuring apparatus for a workpiece to be a screw shaft according to the present invention includes a machining tool for machining a thread groove in a workpiece to be a screw shaft and a table for supporting the workpiece. A measuring element that is disposed so as to be able to contact the thread groove on the side opposite to a processing point for the workpiece by the processing tool, and a position at which the measuring element contacts the screw groove. A positioning device that switches to a position that is not in contact with the thread groove and connects the probe to a support base of the processing tool, and a diameter that is perpendicular to the axial direction and the axial direction of the workpiece. A support mechanism coupled to the positioning device so as to be elastically displaceable in a direction, and an arithmetic processing device that calculates a correction amount of the cutting amount of the machining tool with respect to the workpiece based on the displacement of the probe. An in-process effective diameter in-process measuring device for a workpiece serving as a screw shaft is provided with a plurality of steadying devices arranged below the workpiece on the table and attracting and supporting the workpiece in a V-shaped groove by a magnetic attraction force. It is characterized by that.

  Preferably, the effective diameter in-process measuring device for a workpiece to be a screw shaft according to the present invention is characterized in that the steadying device is fixed to the table and generates a magnetic attraction force, and the upper surface side has the magnetic block. A groove having a V-shaped cross section is formed, and the support block is detachably attached to the upper surface of the magnet block.

  Preferably, in the workpiece effective diameter in-process measuring device serving as the screw shaft according to the present invention, the groove having a V-shaped cross section is formed on a groove surface opposite to a machining point for the workpiece by the machining tool. Has a tilt angle closer to the vertical than the groove surface on the machining point side.

  Preferably, in the effective diameter in-process measuring device for a workpiece serving as a screw shaft according to the present invention, the steadying device can change the magnitude of the magnetic attraction force.

  Preferably, in the workpiece effective diameter in-process measuring device serving as a screw shaft according to the present invention, the steadying device has a V-shaped groove having a different size from the V-shaped groove. It is characterized in that it can be replaced with another supporting block provided.

  In addition, the effective diameter in-process measurement method for a work serving as a screw shaft according to the present invention includes a working tool for working a thread groove on a work serving as a screw shaft and a table for supporting the work. An in-process effective diameter in-process measurement method for a workpiece to be the screw shaft in the above-mentioned method, wherein a position measuring device and a support base for the machining tool are connected to a side opposite to a machining point for the workpiece by the machining tool. An effective diameter in-process measurement method for a workpiece serving as a screw shaft, wherein the measuring element is arranged so as to be in contact with the screw groove, and a cutting amount of the machining tool with respect to the workpiece is corrected based on a displacement of the measuring element. In this case, the waving device is arranged on the table below the work and is supported by a steady rest device that attracts and supports the work in a groove having a V-shaped cross section by a magnetic attraction force. Click is characterized in that it is supported.

  According to the present invention, a screw shaft that can stably support a workpiece that becomes a screw shaft even if the grinding pressure from the grindstone is large, prevent the workpiece from shaking, and improve the dimensional accuracy of the screw shaft after molding. An effective diameter in-process measurement method and an effective diameter in-process measurement apparatus can be provided.

FIG. 1 is a schematic side view of an effective diameter in-process measurement apparatus according to an embodiment, showing a state during measurement and grinding operations. FIG. 2 is an enlarged side view of part A in FIG. FIG. 3 is a front view taken along arrow 3-3 in FIG. FIG. 4 is a side view taken along arrow 4-4 of FIG. 5 (a) is an enlarged plan view of the magnet block, FIG. 5 (b) is a view taken along the line bb of FIG. 5 (a), and FIG. 5 (c) is a cross-sectional view of FIG. 5 (b). FIG. 6A is an enlarged plan view of the support block, and FIG. 6B is a view taken along the line bb in FIG. 6A. 7A and 7B are side views of the effective diameter in-process measurement apparatus, in which FIG. 7A shows a state in which the probe is in the non-measurement position, FIG. 7B shows a state in which the probe is in the measurement preparation position, and FIG. Indicates a state in which the probe is at the measurement position.

Hereinafter, an embodiment of an effective diameter in-process measuring device (hereinafter, abbreviated as “effective diameter in-process measuring device”) and an effective diameter in-process measuring method of a workpiece serving as a screw shaft according to the present invention will be described with reference to the drawings. I will explain. In the present embodiment, the present invention is applied to a screw grinding machine.
First, terms and directions in this specification will be defined. In this specification, “workpiece” refers to a threaded shaft to be processed, which is a cylindrical member that is molded and serves as the threaded shaft of a ball screw device before the thread groove is ground on the outer peripheral surface side. This means a state in which the thread groove is being ground.
Further, in this specification, the front side and the back side of the screw grinder that grinds the workpiece are the front side and the rear side, respectively, and the left and right directions and the up and down directions are the left and right directions when the screw grinder is viewed from the front side. The same applies to the vertical direction.

  FIG. 1 is a schematic side view of a screw grinder equipped with an effective diameter in-process measuring apparatus according to the present embodiment, showing a state during measurement and grinding operations. In FIG. 1, the left side of the paper is the front side (front side) of the screw grinding machine, and the right side of the paper is the rear side (back side). Further, the back side of the paper is the left side of the screw grinding machine, and the front side of the paper is the right side. The upper side of the paper is the upper side of the screw grinder, and the lower side of the paper is the lower side of the screw grinder.

  As shown in FIG. 1, a screw grinding machine 1 that is a processing device for a screw shaft includes a bed 3 that is a main body, and a table 5 that extends in the left-right direction and is movable in the left-right direction on the bed 3; An effective diameter in-process measuring device for measuring an effective diameter of a grinding wheel base 9 provided on the bed 3 and supporting a grinding wheel 7 via a shaft member (not shown) and a workpiece 11 supported by the table 5. 12. The work 11 extends in the left-right direction and is supported by the table 5.

  The table 5 is provided with a spindle stock (not shown) on one side in the left-right direction, and a core push stand (not shown) on the other side in the left-right direction. The headstock supports one end of the work 11 to rotate the work 11, and the core pusher supports the center of the other end face of the work 11 so as to be rotatable. Accordingly, the work 11 is supported by the table 5 so as to be rotatable via the spindle stock and the core push stand in a state where both ends are supported by the spindle stock and the core push stand.

  Since the workpiece 11 is supported by the table 5 as described above, the workpiece 11 moves as the table 5 moves in the left-right direction. As shown in FIG. 1, the processing point for the workpiece 11 by the grinding wheel 7 is a portion located on the back side of the screw grinding machine 1 on the outer peripheral surface of the workpiece 11. The workpiece 11 being processed is rotated by a headstock (not shown) and moves in the axial direction, that is, one side in the left-right direction as the table 5 moves. As the workpiece 11 rotates and moves to one side in the left-right direction, the thread groove of the workpiece 11 is ground by the grinding wheel 7.

  The effective diameter in-process measuring device 12 according to the present embodiment measures the effective diameter of the workpiece 11 by the displacement of the probe 13 that is in contact with the workpiece 11 being processed. As shown in FIG. 1, in the measurement state, the probe 13 is disposed on the front side of the screw grinding machine 1 that is substantially 180 ° opposite to the grinding wheel 7 across the workpiece 11. The measuring element 13 is in contact with a portion of the outer peripheral surface of the work 11 located on the front side of the screw grinding machine 1. Therefore, the effective diameter of the workpiece 11 is measured and ground in a state in which the workpiece 11 is sandwiched between the measuring element 13 and the grinding wheel 7 so as to face each other in the front-rear direction by approximately 180 °.

  Next, a support configuration for arranging the probe 13 on the front side of the screw grinding machine 1 will be described. In the measurement state shown in FIG. 1, the tracing stylus 13 is fixed to the lower surface of the swirling plate 15 and the swiveling plate 15 that extends across the workpiece 11 near the upper portion of the side surface of the grinding wheel 7 and extends horizontally in the front-rear direction. The tracing stylus 13 is connected to the grinding wheel base 9 via the uniaxial table 17 for positioning the tracing stylus. The swivel plate 15 is connected to a shaft member 19 provided on the grindstone table 9 at the rear end, which is the side of the grindstone table 9, and the front end of the swivel plate 15 can be rotated in the upward direction around the shaft member 19. It has become. An air cylinder device 21 is provided at the upper part of the grindstone table 9, and the tip of the piston rod 23 of the air cylinder device 21 is connected to the upper surface of the revolving plate 15. As shown in FIG. 1, when the air cylinder device 21 is driven and the piston rod 23 is moved, the revolving plate 15 is rotated from the horizontal state in the direction in which the front end is directed upward, or the front end is in the upward direction. Rotate in a downward direction from, and become horizontal. The grindstone base 9 is provided with a positioning stopper 25 for prohibiting the turning of the turning plate 15 in a state where the turning plate 15 is in a horizontal state, that is, in a measurement state of the probe 13.

  The uniaxial table 17 for locating the probe has the movable portion 29 in the axial direction of the feed screw shaft via a feed screw shaft (not shown) that is rotated by a pulse motor 27 provided at the end of the uniaxial table 17. It is a linear motion guide device that can be moved to the position. The uniaxial table 17 is fixed to the turning plate 15 along the extending direction of the turning plate 15, and rotates with the turning of the turning plate 15. In the present embodiment, the uniaxial table 17 is arranged such that the movable portion 29 moves in the front-rear direction of the screw grinding machine 1. The movable portion 29 is located on the lower surface side of the single-axis table 17, and a slide block assembly composed of a plurality of slide blocks described later is attached so as to penetrate the movable portion 29 in the vertical direction. As will be described later, the measuring element 13 is attached to the slide block assembly in an elastically supported state.

  2 is an enlarged side view of part A in FIG. 1, FIG. 3 is a front view as seen from the direction of arrow 3-3 in FIG. 2, and FIG. 4 is a side view as seen from the direction of arrow 4-4 in FIG. As shown in FIGS. 2 to 4, the uniaxial table 17 is provided with an upper and lower slide block 31 that penetrates the movable portion 29 and is movable in the vertical direction with respect to the uniaxial table 17. A front / rear slide block 33 that can move horizontally in the extending direction of the uniaxial table 17, that is, the front / rear direction of the screw grinding machine 1, is provided below the upper / lower slide block 31. Further, a left / right slide block 35 that can move horizontally in the extending direction of the work 11 supported by the table 5, that is, the left / right direction of the screw grinding machine 1, is provided below the front / rear slide block 33. These slide blocks 31, 33, and 35 can be moved in the above-described directions by a known manual screw feeding mechanism, and can be clamped by tightening bolts at predetermined positions. Reference numeral 37 denotes a vertical feed screw, 39 denotes a vertical movement clamp bolt, 41 denotes a front / rear direction feed screw, 43 denotes a front / rear movement clamp bolt, 45 denotes a left / right direction feed screw, and 47 denotes a left / right movement clamp bolt.

  As shown in FIGS. 3 and 4, a bracket 49 extending downward adjacent to the slide blocks 31, 33, 35 is attached to the lower surface of the movable portion 29 of the uniaxial table 17. The bracket 49 is configured by connecting three members, and the position can be adjusted vertically, horizontally, and forward and backward. A proximity switch 51 for positioning a probe is attached to the lower end of the bracket 49. The proximity switch 51 is disposed adjacent to the height position substantially the same as that of the measuring element 13 and can be adjusted in the front-rear direction with respect to the bracket 49.

  The lower portions of the left and right slide blocks 35 are partially exposed from the slide guides 53 of the left and right slide blocks 35. As shown in FIGS. A pair of parallel leaf springs 55, 55 for supporting a stylus floating, with the plate surface facing the left-right direction of the panel 1, are attached to extend downward. A floating block 57 is attached to the lower ends of the pair of leaf springs 55, 55. The floating block 57 has a pair of parallel leaf springs 59, 59 for displacement in the measuring direction, with the plate surface facing the radial direction of the workpiece 11 that is horizontally orthogonal to the axial direction of the workpiece 11, that is, the front-rear direction of the screw grinding machine 1. Is attached to extend downward.

  As shown in FIG. 2, the measuring element 13 is horizontally mounted through the pair of plate springs 59, 59 under the pair of plate springs 59, 59 for displacement in the measurement direction. A contact piece 61 is provided at the tip of the measuring element 13, and the contact piece 61 comes into contact with the thread groove flank of the workpiece 11 to be measured with an appropriate measurement pressure by the spring force of the plate spring 59 for displacement in the measurement direction. It is formed in such a size and shape. For example, in the case of the workpiece 11 formed as the screw shaft of the ball screw device as in the present embodiment, the contact piece 61 is composed of a carbide ball having the same size as the ball incorporated in the ball screw device.

  The end of the probe 13 opposite to the contact piece 61 is in contact with the electric micrometer 63. The electric micrometer 63 is held by a bracket 65 attached to a pair of leaf springs 55 and 55 for supporting a probe. The electric micrometer 63 detects the displacement of the contact piece 61 of the probe 13 in the front-rear direction, that is, the radial displacement of the workpiece 11. The contact piece 61 of the probe 13 is in contact with the thread groove of the workpiece 11 at a position approximately 180 ° from the grinding point of the workpiece 11 by the grinding wheel 7, that is, at a position delayed by a half lead. The probe springs 55 and 55 for supporting the probe head are in a vertical relationship with the plate springs 59 and 59 for displacement in the measurement direction that give the measurement pressure of the contact piece 61 to the workpiece 11, and the workpiece spring 11 is being ground. The probe 13 is supported in a floating manner so that the random walk, that is, the wobbling does not affect the measurement. The displacement of the contact piece 61 in the left-right direction (the axial direction of the workpiece 11) is absorbed by the leaf springs 55 and 55 for supporting the probe floating portion by the floating support of the probe 13 in this way. Only the displacement in the radial direction of the workpiece 11 that is orthogonal to the direction is measured by the probe 13.

  Next, the support state of the workpiece 11 on the table 5 will be described. In the present embodiment, as described above, the work 11 is a table that is supported by the headstock (not shown) and the tailstock (not shown) with both ends supported by the headstock and the tailstock. 5 is supported. Thus, in order to prevent the workpiece 11 supported by the table 5 from shaking during processing and to measure an accurate effective diameter, the effective diameter in-process measuring device 12 according to the present embodiment sets the intermediate position of the workpiece 11. A plurality of steady rest devices 67 (see FIG. 1) are provided for support. Each steadying device 67 includes a magnet block 69 that is fixed to the upper surface of the table 5, and a support block 71 that is mounted on the magnet block 69 and contacts the workpiece 11 to support the workpiece 11. The plurality of steady rest devices 67 are arranged on the table 5 at predetermined intervals along the axial direction of the workpiece 11.

5 (a) is an enlarged plan view of the magnet block 69, FIG. 5 (b) is a view taken along the line bb in FIG. 5 (a), and FIG. 5 (c) is a diagram c in FIG. 5 (b). FIG. In FIG. 5A, the vertical direction of the paper is the left-right direction of the screw grinder 1, the left direction of the paper is the front side of the screw grinder 1, and the right direction of the paper is the rear side of the screw grinder 1.
6A is an enlarged plan view of the support block 71, and FIG. 6B is a view taken along the line bb in FIG. 6A. In FIG. 6A, the vertical direction of the paper is the left-right direction of the screw grinder 1, the left direction of the paper is the front side of the screw grinder 1, and the right direction of the paper is the rear side of the screw grinder 1.

  As shown in each drawing of FIG. 5, the magnet block 69 has a rectangular parallelepiped shape, and four projecting portions 73 projecting in the horizontal direction are formed at the lower portion. As shown in FIG. 5A, each projecting portion 73 is provided with a bolt hole 75 penetrating in the vertical direction, and a bolt (not shown) is screwed into the bolt hole 75 so that the magnet block 69 is attached to the table. 5 is fixed to the upper surface. As shown in FIGS. 5A and 5B, the magnet block 69 has a stepped portion 77 with the front edge of the upper surface protruding upward. The front end surface of the support block 71 attached to the upper surface of the magnet block 69 abuts on the stepped portion 77, whereby the support block 71 is positioned in the front-rear direction. Further, the magnet block 69 is provided with bolt holes 79 in the vicinity of each vertex on the upper surface.

  The support block 71 is made of a magnetic material, and has a rectangular parallelepiped shape as shown in FIGS. The support block 71 is formed with a first ridge 81 extending in the left-right direction of the thread grinding machine 1 at the rear side edge of the upper surface, and adjacent to the front side of the first ridge 81. Thus, a second protrusion 83 having a triangular cross section and extending in the left-right direction of the thread grinding machine 1 is formed. A groove 89 having a substantially V-shaped cross section (hereinafter, the groove is abbreviated as “V-shaped groove 89”) is formed by the front-side slope 85 of the first protrusion 81 and the rear-side slope 87 of the second protrusion 83. Is formed. Accordingly, the rear slope 87 of the second protrusion 83 constitutes the front groove face of the V-shaped groove 89, and the front slope 85 of the first protrusion 81 constitutes the rear groove face of the V-shaped groove 89. Yes. Hereinafter, the rear-side inclined surface 87 of the second protrusion 83 is referred to as “the front-side groove surface 87 of the V-shaped groove 89”, and the front-side inclined surface 85 of the first protrusion 81 is referred to as “the rear-side groove surface 85 of the V-shaped groove 89. "

  The front groove surface 87 of the V-shaped groove 89 is formed at an inclination angle closer to the vertical than the rear groove 85 of the V-shaped groove 89. In addition, as shown in FIG. 6B, the top of the second ridge 83 is positioned above the top of the first ridge 81. Therefore, the V-shaped groove 89 has a front-side groove surface 87 having a steeper slope than the rear-side groove surface 85 and extends upward. In the present embodiment, the rear groove surface 85 of the V-shaped groove 89 has an inclination angle of about 30 ° with respect to the horizontal, whereas the front inclined surface has an inclination angle of 45 ° or more with respect to the horizontal, specifically Has an inclination angle of about 60 ° with respect to the horizontal. The work 11 is supported at two points in such a V-shaped groove 89 as shown in FIG. The support block 71 is provided with bolt holes 91 corresponding to the bolt holes 79 on the upper surface of the magnet block 69 in the vertical direction, and bolts (not shown) are screwed into the bolt holes 91 so that the upper surface of the magnet block 69 is secured. Fixed to. In the following description, the support block 71 is also referred to as a “V block 71”.

  Since the magnet block 69 and the V block 71 of the steady rest device 67 have such a configuration, the magnetic attraction force of the magnet block 69 acts on the workpiece 11 via the V block 71, and the workpiece 11 is supported at two points in the V-shaped groove 89. It is adsorbed by. As shown in FIG. 5C, on the side surface of the magnet block 69, an operation handle 93 for turning on / off the magnetic attraction of the magnet block 69 and adjusting the magnitude of the magnetic attraction force is provided. . When the operation handle 93 is operated to turn off the magnetic attraction of the magnet block 69, the magnetic attraction force disappears and the workpiece 11 can be easily detached from the V block 71.

Next, the measurement operation of the effective diameter in-process measurement apparatus 12 according to this embodiment will be described.
7 is a side view of the effective diameter in-process measuring device 12, and FIG. 7 (a) shows a state in which the probe 13 is in a non-measurement position. Specifically, the swivel plate 15 and the front end of the uniaxial table 17 are rotated upward, and the measuring element 13 is far away from the workpiece 11. FIG. 7B shows a state in which the probe 13 is at the measurement preparation position. Specifically, the swivel plate 15 and the single-axis table 17 are in a horizontal state, and the measuring element 13 is positioned in the vicinity of the work 11 while being separated from the work 11. FIG. 7C shows a state in which the probe 13 is at the measurement position. Specifically, the movable portion 29 of the single-axis table 17 is moved from the state shown in FIG. 7B and the measuring element 13 is brought into contact with the workpiece 11.

  First, the work 11 is placed on the table 5 in a predetermined state. That is, the operator turns off the operation handle 93 of each magnet block 69 and arranges the work 11 so that the work 11 is supported at two points in the V-shaped groove 89 of the V block 71 of each steadying device 67. Each end is attached to a headstock (not shown) and a core pusher (not shown) of the table 5, respectively. When the placement of the work 11 on the table 5 is completed, the operation handle 93 of each magnet block 69 is turned on, and the work 11 is attracted to each V block 71 by a magnetic attraction force. The operator operates the air cylinder device 21 and the pulse motor 27 of the uniaxial table 17 to move the probe 13 to a position close to the measurement position shown in FIG. In this state, the operator uses the slide blocks 31, 33, and 35 (see FIGS. 2 to 4) to adjust the position of the measuring element 13 in the vertical direction, the front-rear direction, and the left-right direction, and measures the screw groove of the workpiece 11. The positional relationship between the proximity switch 51 (see FIG. 4) for positioning the probe and the probe 13 is set so that the contact piece 61 of the probe 13 makes a light contact. Thereafter, the operator operates the air cylinder device 21 and the pulse motor 27 of the uniaxial table 17 to return the measuring element 13 to the measurement preparation position shown in FIG. 7B, and further to the non-measurement shown in FIG. Return to position. Then, the table 5 is moved so that the grinding wheel 7 and the tracing stylus 13 are located at the grinding start point of the workpiece 11.

  Thereafter, when grinding is started, the air cylinder device 21 and the pulse motor 27 of the single-axis table 17 are driven by the control of the control system of the screw grinder 1, and the probe 13 is moved from the non-measurement position of FIG. It is moved to the measurement preparation position shown in (b), and further moved to the measurement position of FIG. The contact piece 61 of the probe 13 comes into contact with the thread groove of the workpiece 11 and the measurement of the effective diameter of the workpiece 11 is started.

  Even if there is a slight fluctuation in the cutting feed amount of the grinding wheel 7, a fluctuation in the lead of the thread groove of the workpiece 11, or a fluctuation in the grinding amount due to the bending of the workpiece 11, the probe 13 has two sets of parallel leaf springs 55 and 59. The contact piece 61 is not separated from the thread groove of the work 11 because it is pressed against the work 11 by (see FIGS. 2 to 4). The radial displacement of the measuring element 13 due to the contact of the contact piece 61 with the thread groove is taken out by the electric micrometer 63, passed through the amplifier 95 (see FIG. 1), the A / D converter 97, and the arithmetic processing unit 99. The difference in the effective diameter, that is, the variation is calculated, and a cutting amount correction command for the grinding wheel base 9 is output. The measurement result is displayed on the CRT display unit 101 and the plotter 103. In this case, the correction amount of the cutting amount of the grinding wheel base 9 is calculated by storing the data immediately after the start of measurement in the arithmetic processing unit 99 as a reference, and comparing the stored reference data with the measured values sequentially taken in. Calculated by the processing device 99. Based on the calculated correction amount, the arithmetic processing unit 99 outputs a correction command to the grindstone cutting servo motor (not shown) so that the effective diameter of the workpiece 11 is always the same as the reference value immediately after the start of measurement. Control the grinding wheel base cutting servo motor.

  When the correction of the cutting amount of the grinding wheel base 9 and the grinding for one stroke are completed, the movable portion 29 of the uniaxial table 17 holding the measuring element 13 is driven and the measuring element 13 is in a measurement preparation position (see FIG. 7B). At the same time, the uniaxial table 17 is rotated upward and retracted together with the swivel plate 15, and the probe 13 is moved to the non-measurement position (see FIG. 7A). Then, the operations shown in FIG. 7B and FIG. 7C are performed again from the state shown in FIG. 7A to start grinding and measurement. Thus, the effective diameter in-process measurement of the workpiece 11 is performed in the screw grinder 1, and the grinding wheel cutting position feedback control and machining for correcting the difference in effective diameter based on the measured data are performed.

  In the present embodiment, the workpiece 11 is stably supported in the V-shaped groove 89 of each V block 71 by the magnetic attractive force of the plurality of magnet blocks 69 during the above-described grinding process. Therefore, it is possible to prevent the workpiece 11 from swinging during the grinding of the workpiece 11. Further, the V-shaped groove 89 of each V block 71 has a front side groove surface 87, that is, a groove surface opposite to the processing point of the grinding wheel 7 across the work 11 has a steeper slope than the rear side groove surface 85. Moreover, since the workpiece 11 extends upward, the workpiece 11 is prevented from moving forward by the front groove surface 87 even if the grinding pressure by the grinding wheel 7 is large. Therefore, the workpiece 11 is stably held in the V-shaped groove 89 without shaking during grinding. As a result, the dimensional accuracy of the screw shaft after molding can be improved.

  Further, the effective diameter in-process measuring device 12 according to the present embodiment facilitates the V block 71 by releasing the screwing of the bolt that fixes the V block 71 to the magnet block 69 and removing the bolt from the bolt hole. The magnet block 69 can be removed. That is, the V block 71 is detachably attached to the magnet block 69. Therefore, if a plurality of types of V blocks 71 having V-shaped grooves 89 having various depth dimensions are prepared, the workpiece 11 having a plurality of diameters can be handled by replacing the V block 71. That is, even when the diameter of the workpiece 11 is changed, if the V block 71 having the V-shaped groove 89 having a size suitable for the changed diameter of the workpiece 11 is replaced, the screw shaft after forming is changed. Dimensional accuracy can be improved.

  Furthermore, the effective diameter in-process measurement device 12 according to the present embodiment operates the operation handle 93 (see FIG. 5C) to set the magnitude of the magnetic attraction force of the magnet block 69 to the size of the workpiece 11, that is, the outside. It can be adjusted to a size suitable for the diameter, length, or weight. Accordingly, it is possible to prevent the magnetic attracting force from being too large with respect to the size of the work 11 to hinder the rotation of the work 11, or the magnetic attracting force from being too small to shake the work 11 during grinding. can do. When the outer diameter dimension of the workpiece 11 is changed, the magnitude of the magnetic attractive force may be adjusted according to the size of the workpiece 11 after the change. As described above, according to the present embodiment, the work 11 is stably held in the V-shaped groove 89 of the V block 71 regardless of the outer diameter of the work 11 and even if the grinding pressure by the grinding wheel 7 is large. , Can prevent shake. As a result, the dimensional accuracy of the screw shaft after molding can be improved.

DESCRIPTION OF SYMBOLS 1 Screw grinding machine 3 Bed 5 Table 7 Grinding wheel 9 Grinding wheel base 11 Work 12 Effective diameter in-process measuring device 13 Measuring element 15 Rotating plate 17 Single axis table 19 Shaft member 21 Air cylinder device 23 Piston rod 25 Positioning stopper 27 Pulse motor 29 Movable part 31 Vertical slide block 33 Front / rear slide block 35 Left / right slide block 37 Vertical feed screw 39 Vertical clamp bolt 41 Front / rear feed screw 43 Front / rear clamp bolt 45 Left / right feed screw 47 Left / right clamp bolt 49 Bracket 51 Proximity switch 53 Slide Guide 55 Parallel Plate Spring 57 for Floating Probe 57 Floating Block 59 Parallel Plate Spring 61 for Measuring Direction Displacement Contact Piece 63 Electric Micrometer 65 Bracket 67 Stabilizer 69 Magnet Lock 71 Support block 73 Protruding part 75 Bolt hole 77 Step part 79 Bolt hole 81 1st protrusion 83 2nd protrusion 85 1st protrusion slope 87 2nd protrusion slope 89 V-shaped groove 91 Bolt Hole 93 Operation handle 95 Amplifier 97 A / D converter 99 Arithmetic processing unit 101 CRT display unit 103 Plotter

Claims (6)

Provided in a processing apparatus comprising a processing tool for processing a thread groove in a work to be a screw shaft and a table for supporting the work,
A probe arranged so as to be able to contact the thread groove on the side opposite to the machining point for the workpiece by the machining tool;
A positioning device that switches the probe to a position that contacts the screw groove and a position that does not contact the screw groove, and connects the probe to a support of the processing tool;
A support mechanism that connects the measuring element to the positioning device so as to be elastically displaceable in the radial direction perpendicular to the axial direction and the axial direction of the workpiece;
In an effective diameter in-process measuring device for a workpiece to be a screw shaft, comprising an arithmetic processing device that calculates a correction amount of a cutting amount of the machining tool with respect to the workpiece based on the displacement of the measuring element,
An effective diameter of a work serving as a screw shaft, comprising a plurality of steady rest devices arranged on the table below the work and attracting and supporting the work in a groove having a V-shaped cross section by a magnetic attraction force In-process measurement device.   The steady rest device includes a magnet block that is fixed to the table and generates the magnetic attractive force, and a support block that is formed with a V-shaped groove on the upper surface side and is detachably attached to the upper surface of the magnet block. The in-process effective diameter in-process measuring device for a workpiece to be a screw shaft according to claim 1.   The groove having the V-shaped cross section has an inclination angle that is closer to the vertical of the groove surface on the opposite side to the machining point on the workpiece by the machining tool than the groove surface on the machining point side. The effective diameter in-process measuring apparatus of the workpiece | work used as the screw shaft of Claim 1 or 2.   4. The effective diameter in-process measuring device for a workpiece to be a screw shaft according to claim 1, wherein the steadying device is capable of changing a magnitude of the magnetic attraction force. 5.   The said steadying apparatus can be replaced | exchanged for the other support block provided with the groove | channel of the cross-sectional V shape of the magnitude | size different from the groove | channel of the said V-shaped cross section. An effective diameter in-process measuring device for a workpiece to be a screw shaft according to one item. An effective diameter in-process measurement method for a workpiece to be a screw shaft in a processing apparatus provided with a processing tool for processing a thread groove in a workpiece to be a screw shaft and a table for supporting the workpiece,
With the positioning device connecting the measuring element and the support base of the processing tool, the measuring element is arranged so as to contact the thread groove on the side opposite to the processing point for the workpiece by the processing tool,
In an in-process effective diameter in-process measurement method of a workpiece to be a screw shaft, which corrects a cutting amount of the machining tool with respect to the workpiece based on the displacement of the probe,
A work serving as a screw shaft, which is arranged below the work on the table and supported by a steadying device that attracts and supports the work in a groove having a V-shaped cross section by a magnetic attraction force. Effective diameter in-process measurement method.

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