JP2010064192A - Grinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinder in which machining cost and time can be decreased by decreasing the number of times of truings. <P>SOLUTION: In the grinder having a plurality of grinding wheels and capable of carrying out rough grinding and finish grinding to a workpiece, the grinder includes a threshold storage part for storing a threshold which determines that the state of a grinding surface of a grinding wheel for finish grinding used for finish grinding among the grinding wheels is in a limit state, and a detection means for detecting the state of the grinding surface of the grinding wheel for finish grinding. A control means carries out control so as to use a grinding wheel which has been used for finish grinding so far as a grinding wheel for rough grinding without applying truing to the grinding surface of the grinding wheel when the detection result of the detection means reaches the threshold, applies trueing to a grinding surface of a grinding wheel which has been used for rough grinding so far, and thereafter uses the grinding wheel as a grinding wheel for finish grinding. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a grinder capable of performing rough grinding and finish grinding on a workpiece.

  In general, there are two processing stages of grinding by a grinding machine, and it can be divided into a rough grinding process performed in the previous stage and a finish grinding (fine grinding) process performed in the subsequent stage. In this case, rough grinding is performed using a rough grinding wheel, and finish grinding is performed using a finish grinding wheel. When the grinding surface of each grindstone becomes unevenly worn, rough, worn, etc., it becomes impossible to grind the workpiece with a desired accuracy, and the grinding surface is trued.

By the way, what was disclosed by patent document 1 is known as a grinding machine which can perform both a rough grinding process and a finish grinding process with respect to one workpiece, for example. This grinder includes two types of grindstones for rough grinding and finish grinding, and the grindstone used for rough grinding and finish grinding is switched by a turning mechanism.
JP 58-28459 A

  By the way, the grinding wheel for finishing grinding employed in the above grinding machine is designed to perform truing periodically after a predetermined time or after a predetermined number of times in order to ensure the target finishing accuracy of the workpiece. Many abrasive grains are scraped off from a grindstone by truing. The price of the scraped abrasive grains is a part of the processing cost of the product. Therefore, if the truing amount by which the grindstone is scraped off by truing is large, the total processing cost becomes high. In particular, since the CBN grindstone and the diamond grindstone are extremely expensive, when these grindstones are employed, the processing cost increases significantly when the number of abrasive grains scraped off by truing increases. In addition, since the truing time is added to the machining cycle time, the total machining time becomes longer and the machining cost increases as the number of truing times increases.

  The present invention has been made in view of the above circumstances, and an object to be solved is to provide a grinding machine capable of reducing machining costs and machining time.

  In order to solve the above-mentioned problem, the structural feature of the invention according to claim 1 is provided with a plurality of grindstones, roughly grinding a workpiece with any one of the plurality of grindstones, In a grinding machine configured to finish-grind a workpiece with a grindstone, a threshold value memory for memorizing a threshold value for judging that a state of a grinding surface of a grindstone for finish grinding used for finish grinding among the grindstones is a limit state And a detecting means for detecting a state of the grinding surface of the grinding wheel for finish grinding, and when the detection result of the detecting means reaches the threshold value, the grinding surface of the grindstone used for the finishing grinding process And a control means for using the grindstone as a rough grinding grindstone without performing truing.

  In the present invention, the threshold value for judging the state of the grinding surface of the grinding wheel for finish grinding is that the state of the grinding surface of the grinding wheel is deteriorated due to uneven wear, surface roughness, abrasive wear, etc. It is set on the basis of a state in which use as a grindstone is inappropriate.

  The structural feature of the invention according to claim 2 is that in claim 1, the control means grinds the grindstone used for the rough grinding when the detection result of the detection means reaches the threshold value. After truing the surface, the grindstone is used as a grindstone for finish grinding.

  The structural feature of the invention according to claim 3 is that, in the first or second aspect, the threshold value is set to the grinding process until the state of the grinding surface of the grindstone used for the finish grinding process reaches the limit state. The number of workpieces that can be processed, and the detection means is a counter that counts the number of workpieces to be processed.

  The structural feature of the invention according to claim 4 is that, in claim 1 or claim 2, the threshold is the threshold value when the state of the grinding surface of the grindstone used for the finish grinding is in the limit state. It is the amount of wobbling of the grindstone, and the detecting means is a displacement sensor that measures the amount of displacement of the grindstone.

  A structural feature of the invention according to claim 5 is that, in the first or second aspect, the threshold value is determined by grinding until the state of the grinding surface of the grindstone used for the finish grinding process reaches the limit state. The accumulated processing time of the grindstone is possible, and the detecting means is a time measuring device that measures the accumulated processing time of the grindstone.

  The structural feature of the invention according to claim 6 is that, in claim 1 or claim 2, the threshold value is determined when the grinding surface of the grindstone used in the finish grinding process is in the limit state. The grinding resistance is generated when the workpiece is ground with a grindstone, and the detection means is a measuring instrument for measuring the grinding resistance.

  The structural feature of the invention according to claim 7 is that in any one of claims 1 to 6, the grindstone is a CBN grindstone or a diamond grindstone.

  According to the first aspect of the present invention, the threshold for determining that the state of the grinding surface of the grindstone for finish grinding used for finish grinding in the grindstone is in the limit state is stored in the threshold storage unit, and the finish grinding process is performed. The state of the grinding surface of the grindstone is detected by the detecting means, and when the detection result of the detecting means reaches the threshold value, the grindstone is removed without performing truing on the grinding surface of the grindstone used for finish grinding. Since it is used as a grindstone for rough grinding, truing on the grindstone can be omitted when switching from a grindstone for finish grinding to a grindstone for rough grinding. Therefore, the number of times of truing can be reduced, and the amount of abrasive grains to be scraped off when performing truing can be reduced, so that the total processing cost can be reduced. Further, since the truing time can be shortened as the number of truing times is reduced, the total processing time can be shortened.

  According to the invention of claim 2, after the truing is performed on the grinding surface of the grindstone used for the rough grinding when the measurement result of the measuring means reaches the threshold value, the grindstone is used for finishing grinding. Therefore, it is possible to ensure that there are always two types of grindstones for rough grinding and finish grinding.

  According to the invention of claim 3, since the number of workpieces that can be ground before the grinding surface of the grindstone used for finish grinding reaches the limit state is set as a threshold value, By measuring the number of machining, it is possible to easily detect that the state of the ground surface has reached the limit state.

  According to the fourth aspect of the present invention, since the amount of wobbling of the grindstone when the state of the grinding surface of the whetstone used for finish grinding reaches a limit state is set as a threshold value, the amount of wobbling of the grindstone is measured by the displacement sensor. By doing so, it is possible to easily detect that the state of the ground surface has reached the limit state.

  According to the fifth aspect of the present invention, since the cumulative processing time of the grindstone that can be ground until the state of the grinding surface of the grindstone used for finish grinding reaches the limit state is set as a threshold value, By measuring the accumulated machining time, it is possible to easily detect that the state of the ground surface has reached the limit state.

  According to the invention which concerns on Claim 6, when the state of the grinding surface of the grindstone used for finish grinding reaches the limit state, the grinding resistance generated during grinding of the workpiece with the grindstone is used as the threshold value. By measuring the grinding resistance with a measuring instrument, it is possible to easily detect that the state of the ground surface has reached the limit state.

  According to the seventh aspect of the present invention, since the abrasive grains scraped off by the truing of an extremely expensive CBN grindstone or diamond grindstone can be reduced, the effect of reducing the machining cost can be obtained more advantageously.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings. FIG. 1 shows an entire grinding machine 10 equipped with a grindstone turning device 20, and a workpiece table 12 is guided and supported on a bed 11 of the grinding machine 10 so as to be movable in the horizontal Z-axis direction. It is moved in the Z-axis direction by a Z-axis servo motor 75. A headstock 13 and a tailstock 14 are installed on the workpiece table 12 so as to face each other, and the spindle stock 13 and the tailstock 14 are provided with centers 15 and 16 for supporting both ends of the workpiece W. . The workpiece W supported by both the centers 15 and 16 is parallel to the moving direction (Z-axis direction) of the workpiece table 12 through a driving bracket (not shown) by a spindle driving motor 17 installed on the headstock 13. It is designed to rotate around the axis.

  On the bed 11, the grindstone table 18 is guided and supported so as to be movable in the horizontal X-axis direction orthogonal to the moving direction of the workpiece table 12, and is moved forward and backward in the X-axis direction by the X-axis servo motor 71. It has become. On the grindstone table 18, a grindstone turning device 20 and a grindstone base 40 are installed.

  As shown in FIG. 2, the grindstone turning device 20 includes a support base 21 fixed on the grindstone table 18, and a horizontal plane around the B axis (see FIG. 1) around the swivel axis 22. It has the turntable 23 supported so that turning is possible. The support base 21 is formed with a large-diameter cylindrical portion 21a, and a turning shaft 22 is erected in the vertical axis direction at the center of the large-diameter cylindrical portion 21a. A small diameter cylindrical portion 21 b fixed to the swivel base 23 is fitted to the swivel shaft 22.

  An outer ring of a cross roller bearing 51 is concentrically fixed to the turning shaft 22 in the large diameter cylindrical portion 21 a of the support base 21, and an intermediate cylindrical portion 23 a connected to the turning base 23 is connected to the inner ring of the cross roller bearing 51. The swivel base 23 is connected to the support base 21 via a cross roller bearing 51 so as to be pivotable about the swivel axis 22. A direct drive motor 52 is disposed in an annular space formed between the large diameter cylindrical portion 21 a of the support base 21 and the intermediate cylindrical portion 23 a of the swivel base 23. It is designed to be swiveled.

  The direct drive motor 52 includes a rotor 53 fixed to the outer periphery of the intermediate cylindrical portion 23 a of the swivel base 23 and a stator 54 fixed to the inner periphery of the large-diameter cylindrical portion 21 a of the support base 21. A plurality of flat permanent magnets are bonded to the outer periphery of the rotor 53, and a plurality of coils are wound around the inner periphery of the stator 54 so as to face the permanent magnets. As a result, the rotor 53 is rotated and the swivel base 23 is swung.

  The turning angle of the turntable 23 that is turned by the rotation of the rotor 53 of the direct drive motor 52 is detected by the encoder 55 installed on the support table 21. The swivel base 23 is indexed and rotated to the command angle position by the direct drive motor 52 based on the detection signal of the encoder 55, and is fixed to the command angle position by the brake means 56.

  The brake means 56 is disposed in an annular space formed between the intermediate cylindrical portion 23a fixed to the swivel base 23 and the small diameter cylindrical portion 21b, and a brake cylinder 57 formed on the support base 21 side, The piston 58 is fitted to the brake cylinder 57 so as to be slidable in the vertical direction, and the friction plate 59 is fixed to the intermediate cylindrical portion 23a. The swivel base 23 can be fixed at a predetermined angular position by sandwiching the friction plate 59 between the piston 58 and the flange portion fixed to the bottom surface of the large diameter cylindrical portion 21a.

  A grindstone shaft 41 having both ends projecting horizontally from both the left and right sides of the grindstone table 40 is rotatably supported at the front side (workpiece table 12 side) of the grindstone table 40, and the projecting portions at both ends of the grindstone shaft 41 are supported. The 1st whetstone 42 and the 2nd whetstone 43 are attached to, respectively. The first and second grindstones 42 and 43 are CBN grindstones. The first and second grindstones 42 and 43 are used for finish grinding and rough grinding depending on the state of the respective grinding surfaces 42a and 43a, and one of the grindstones is used for finish grinding. When this is done, the other grindstone is used for rough grinding.

  The grindstone shaft 41 is driven to rotate by a built-in motor 45 provided inside the grindstone table 40. By driving the built-in motor 45, the first and the first wheel shafts 41 attached to the grindstone shaft 41 are driven. The second grindstones 42 and 43 are driven to rotate.

  As shown in FIG. 1, a truing device 68 having a truing tool 67 for truing the first and second grindstones 42 and 43 is disposed on the head stock 13 installed on the workpiece table 12. . The truing device 68 is configured so that the grinding wheel shaft 41 is positioned in parallel with the Z axis, and the first and second grinding wheels 42 are moved forward by cutting the grinding wheel table 18 in the X-axis direction and traversing the workpiece table 12 in the Z-axis direction. 43, the ground surfaces 42a and 43a are trued.

  The truing for the first and second grindstones 42 and 43 is the detection result of the detecting means for detecting the state of the grinding surface of the grindstone for finish grinding used for finish grinding among the first and second grindstones 42 and 43. It is performed when the grinding surface of the finish grinding wheel reaches a threshold value for determining that the state of the grinding surface has reached a limit state. In this embodiment, the threshold for determining that the state of the grinding surface of the grinding wheel for finish grinding has reached the limit state is set based on the number of workpieces W processed. That is, as the number of workpieces W increases, uneven grinding, surface roughness, wear, etc. occur in the grinding wheel for finish grinding, and the judgment criteria that the use as the grinding wheel for finish grinding becomes inappropriate Is based on the number of workpieces W processed. A threshold value storage unit 91 for storing the threshold value is provided in a memory 62 of the numerical controller 60 described later. Further, as the detection means, a counter 92 that counts the number of workpieces W is employed, and this counter 92 is provided in a memory 62 of a numerical controller 60 described later.

  In the case of the present embodiment, when the count result of the counter 92 reaches a threshold value, the grindstone is used for rough grinding without performing truing on the grinding surface of the grindstone that has been used for finish grinding until that time. A control program 93 for controlling the grindstone to be used as a grindstone for finishing grinding after the truing device 68 performs truing on the grinding surface of the grindstone that has been used as a grindstone and used for rough grinding until then. (Control means) is stored in the memory 62. That is, the truing by the truing device 68 for the first and second grindstones 42 and 43 is performed only for the grindstone used for the rough grinding, and is performed for the grindstone used for the finish grinding. Absent.

  As shown in FIG. 3, the numerical controller 60 for controlling the grinding machine 10 is mainly configured by a central processing unit 61, a memory 62 for storing various control values and programs, and interfaces 63 and 64. . The memory 62 stores various data necessary for executing a grinding cycle and a truing cycle such as a grinding program, a truing program, and a control program 93. The memory 62 is provided with a threshold storage unit 91 that stores a threshold for determining the state of the grinding surface of the grinding wheel for finish grinding. Various data are input to the numerical control device 60 through an input device 65. The input device 65 includes a keyboard for inputting data and a display device for displaying data. Yes.

  The numerical control device 60 is adapted to give a drive signal to an X-axis servo motor 71 that moves the grindstone table 18 in the X-axis direction via the X-axis motor drive unit 70, and is attached to the X-axis servo motor 71. The encoder 72 is configured to send the rotational position of the X-axis servomotor 71, that is, the position in the X-axis direction of the grindstone table 18 to the X-axis motor drive unit 70 and the numerical controller 60.

  Further, the numerical controller 60 gives a drive signal to the Z-axis servomotor 75 that moves the workpiece table 12 in the Z-axis direction via the Z-axis motor drive unit 74. The attached encoder 76 is configured to send the rotational position of the Z-axis servo motor 75, that is, the Z-axis direction position of the workpiece table 12 to the Z-axis motor drive unit 74 and the numerical controller 60.

  Further, the numerical controller 60 gives a drive signal to the direct drive motor 52 for turning the swivel base 23 around the B axis via the B axis motor drive unit 78, and is connected to the direct drive motor 52. The encoder 55 is configured to send the rotational position of the direct drive motor 52, that is, the turning position of the turntable 23 to the B-axis motor drive unit 78 and the numerical controller 60.

  Further, the memory 91 of the numerical controller 60 stores a counter 92 (counting program) for counting the number of workpieces W processed by the first and second grindstones 42 and 43, and the number of workpieces W processed is calculated. It is configured to instruct the start of the truing operation when the threshold stored in the threshold storage unit 91 is reached.

  Next, the grinding operation of the grinding machine configured as described above will be described. In the present embodiment, as shown in FIG. 1, the first and second grindstones 42 and 43 with respect to the workpiece W supported at both ends by the headstock 13 and the tailstock 14 on the workpiece table 12. Perform rough grinding and finish grinding (fine grinding). At the present time, the first grindstone 42 is used for finish grinding, and the second grindstone 43 is used for rough grinding.

  First, when performing rough grinding on the workpiece W, the first and second grindstones 42 and 43 are rotationally driven by the grindstone shaft driving motor 45. When the start of the grinding cycle is commanded, the workpiece W supported at both ends by the centers 15 and 16 of the headstock 13 and the tailstock 14 is rotationally driven by the spindle driving motor 17 to process on the workpiece W. The workpiece table 12 is positioned so that the portion Wa is positioned at the Z-axis direction position corresponding to the second grinding wheel 43 for rough grinding.

  Subsequently, the grindstone table 18 is advanced in the X-axis direction by the X-axis servomotor 71, and the processed portion Wa of the workpiece W is roughly ground by the second grindstone 43 for rough grinding. When the rough grinding of the processing portion Wa is completed, the grindstone table 18 is retracted in the X-axis direction by the X-axis servomotor 71, and then the swivel base 23 on the grindstone table 18 is directly moved based on a command from the numerical controller 60. The drive motor 52 turns 180 ° around the B axis (the turning shaft 22), and the grinding wheel base 40 is positioned at an angular position where the first grinding wheel 42 for finish grinding faces the processing portion Wa of the workpiece W.

  Subsequently, the grindstone table 18 is advanced in the X-axis direction by the X-axis servo motor 71, and the machining portion Wa of the workpiece W is finish-grinded by the first grindstone 42 for finish grinding, and the workpiece W is ground. Ends. When the finish grinding of the processing portion Wa is completed, the grindstone table 18 is retracted in the X-axis direction by the X-axis servomotor 71, and the swivel base 23 is rotated 180 ° around the B-axis (swivel axis 22) by the direct drive motor 52. Then, the grinding wheel base 40 is positioned at an angular position at which the second grinding wheel 43 for rough grinding is opposed to the processing portion Wa of the workpiece W.

  Thereafter, the workpiece W that has been ground is removed from the headstock 13 and the tailstock 14, and the workpiece W to be ground next is set between the headstock 13 and the tailstock 14 with both ends supported. To do. Similarly to the above, the workpiece W is subjected to rough grinding with the second grindstone 43 and finish grinding with the first grindstone 42.

  In this way, grinding by the first and second grindstones 42 and 43 is sequentially performed on a large number of workpieces W. At this time, the number of workpieces W processed by the counter 92 (counting program) provided in the numerical controller 60 is counted, and the number of workpieces processed by the first grindstone 42 for finish grinding is stored in the threshold storage unit 91. When the threshold value is reached, the numerical control device 60 commands the start of the truing operation. Hereinafter, the truing operation of the first and second grindstones 42 and 43 will be described based on the flowchart shown in FIG. 4 and the timing chart shown in FIG.

  When the number of workpieces W reaches the threshold value, the first grindstone 42 that has been used for finish grinding by the control program 93 until that time is used as a rough grinding grindstone without performing truing. . On the other hand, the second grindstone 43 that has been used for rough grinding until then is used as a grindstone for finish grinding after truing with the truing device 68.

  When truing the second grindstone 43, the workpiece table 12 is positioned so that the truing tool 67 of the truing device 68 is located at the Z-axis direction position corresponding to the grinding surface 43a of the second grindstone 43. Is started.

  Based on the truing start command, the grindstone table 18 is advanced in the X-axis direction by the X-axis servo motor 71, and the truing tool 67 performs truing of the grinding surface 43 a of the second grindstone 43. At this time, the grinding surface 43a of the second grindstone 43 is trued to a predetermined fine roughness so as to be used for finish grinding, and the second grindstone 43 after truing is finished in the subsequent grinding cycle. It is used as a grinding wheel for finish grinding until the number of workpieces W processed by the first grinding wheel 42 for grinding reaches the threshold value stored in the threshold value storage unit 91.

  That is, when the threshold value of the number of workpieces W processed by the first grinding wheel 42 for finish grinding this time (first time) is reached, the first grinding wheel 42 is switched from being used for finish grinding to being used for rough grinding. Then, the second grindstone 43 is switched from rough grinding to finish grinding after truing (see FIG. 5).

  Thereafter, based on a grinding cycle start command from the numerical controller 60, a grinding cycle similar to the above is restarted, and grinding by the first and second grindstones 42 and 43 on a number of workpieces W is sequentially performed. . Then, when the number of workpieces W processed by the second grindstone 43 for finish grinding reaches the threshold value stored in the threshold value storage unit 91, the start of the truing operation is instructed again. In this case, the second grindstone 43 that has been used for finish grinding until the number of workpieces W reaches the threshold value is used as it is as a rough grinding grindstone without performing truing. The truing device 68 performs truing only on the ground surface 42a of the first grindstone 42 that has been used for rough grinding until that time.

  The truing with respect to the first grindstone 42 is performed in the same manner as described above based on the truing operation start command by the numerical controller 60. The first grindstone 42 after the truing is finished is used for finish grinding in the subsequent grinding cycle. Until the number of workpieces W processed by the first grindstone 42 reaches the threshold value stored in the threshold value storage unit 91, it is used as a grindstone for finish grinding. That is, when the threshold value of the number of workpieces W processed by the second grinding wheel 43 for finish grinding this time (second time) is reached, the second grinding wheel 43 is switched from the finish grinding process to the rough grinding process as it is. Thus, the first grindstone 42 is switched from rough grinding to finish grinding after truing (see FIG. 5).

  In addition, FIG. 6 is explanatory drawing which shows the change of the grinding surface 42a accompanying use of the 1st grindstone 42 in this Embodiment. As shown in FIG. 6A, the first grindstone 42 used for the finish grinding first as shown in FIG. 6A, when the number of workpieces W processed by the first grindstone 42 reaches the threshold value, as shown in FIG. 6B. In addition, the state of the grinding surface 42a is deteriorated due to uneven wear, surface roughness, abrasive grain wear, and the like, and it is determined that the grinding surface 42a is inappropriate for use as a grinding wheel for finish grinding, and thereafter shown in FIGS. 6 (b) and 6 (c). Thus, it is used as a grindstone for rough grinding. After that, the first grindstone 42 used in the rough grinding process is caused by uneven wear, surface roughness, abrasive grain wear, etc. when the number of workpieces W processed by the second grindstone for finish grinding reaches a threshold value. After the further deteriorated grinding surface 42a is repaired by truing, it is used as a grindstone for finish grinding as shown in FIG. 6 (d).

  As described above, according to the present embodiment, when the detection result of the detection means reaches the threshold value, the grindstone is not subjected to truing on the grinding surface of the grindstone used for finish grinding. Since it is used as a grindstone for rough grinding, truing on the grindstone can be omitted when switching from a grindstone for finish grinding to a grindstone for rough grinding. Therefore, in the above embodiment, the number of truing operations can be reduced to ½, and as a result, the amount of abrasive grains to be scraped off when performing truing can be reduced, thereby reducing the overall processing cost. can do. In the present embodiment, since the truing of the first and second grindstones 42 and 43 is not performed at the same time but sequentially, the truing time is reduced as the number of truing operations is reduced, and the total processing time is reduced. Can be shortened. In particular, in the present embodiment, since the first and second grindstones 42 and 43 are extremely expensive CBN grindstones, the effect of reducing the processing cost can be obtained more advantageously.

  In addition, when the detection result (counting result) of the detecting means (counting program that is the counter 92) reaches a threshold value, the grinding surface of the grindstone used for the rough grinding process is trued and then the grindstone is finished. Since it is used as a grindstone for grinding, it is possible to ensure that there are always two types of grindstones for rough grinding and finish grinding. Thereby, the rough grinding process and the finish grinding process by the first and second grindstones 42 and 43 can be smoothly and efficiently performed.

  Furthermore, the threshold value stored in the threshold value storage unit 91 is the limit until the grindstone is used as a grinding surface for finish grinding after the grindstone used for rough grinding is trued for finish grinding. The counter 92 (counting program) that counts the number of workpieces W processed as a detecting means is adopted as the number of workpieces that can be ground by the grindstone used as the grinding wheel for finish grinding. The threshold value can be easily set, and the counter 92 can be manufactured at a low cost to avoid a significant cost increase.

  Next, a second embodiment of the present invention will be described with reference to FIG. In the grinding machine 100 according to the second embodiment, the first and second grindstones 42 and 43 are attached to the two grindstone shafts 111 and 112, respectively, and the state of the grinding surface of the grinding wheel for finish grinding is determined. A threshold value to be determined is set based on the amount of deflection of the first and second grindstones 42 and 43, and a non-contact type displacement sensor as detection means for detecting the amount of displacement (the amount of deflection) of the first and second grinding wheels 42 and 43. Since 142 and 143 are employed, the grinding machine 10 is different from the grinding machine 10 according to the first embodiment and the other points are the same. Therefore, the differences will be mainly described below. In FIG. 7, members that are the same as those in the first embodiment are given the same reference numerals, and detailed descriptions thereof are omitted.

  As shown in FIG. 7, two grindstone shafts 111 and 112 are supported on the swivel base 23 so as to be rotatable around horizontal axes parallel to each other. And the 2nd grindstones 42 and 43 are attached, respectively. The first and second grindstones 42, 43 have grinding surfaces 42a, 43a parallel to the grindstone axes 111, 112, and are perpendicular to the surface S that bisects perpendicularly to the grinding surfaces 42a, 43a. The first and second grindstones 42 and 43 are positioned so that the center of rotation is included.

  The swivel base 23 has a rectangular shape when viewed from the plane. Of the four side surfaces of the swivel base 23, two opposing side surfaces 121 and 122 (hereinafter referred to as a first side surface 121 and a second side surface 122) are provided with first and second grindstone holding means 123 and 124, respectively. ing. Since the first and second grindstone holding means 123 and 124 have the same configuration, the configuration of the first grindstone holding means 123 provided on the first side surface 121 will be described below.

  A pair of bearing portions 125 and 126 are installed on the first side surface 121 of the swivel base 23 with a predetermined interval in the horizontal direction, and the grindstone shaft 111 is rotated around a horizontal axis by the bearing portions 125 and 126. Both ends are supported as possible. The grindstone shaft 111 is positioned at an angular position parallel to the rotation axis of the workpiece W when the swivel base 23 is swung 180 degrees around the swivel shaft 22.

  A pulley 134 is attached to one end of the grindstone shaft 111 (the left end in FIG. 7). The pulley 134 is a pulley 146 and a belt 147 attached to the motor shaft of the grindstone shaft drive motor 145 installed on the swivel base 23. It is connected via rotation.

  A recess 121a is formed on the first side surface 121 of the swivel base 23 corresponding to the first grindstone 42, and a part of the outer periphery of the first grindstone 42 enters the recess 121a. Even when the diameter of the 1st grindstone 42 is large by making a part of outer periphery of the 1st grindstone 42 penetrate | invade into the recessed part 121a of the swivel base 23, it is from the 1st side surface 121 of the swivel base 23 to the center position of the grindstone axis | shaft 111. The distance, that is, the amount of overhang is suppressed from increasing, and the support rigidity of the grindstone shaft 111 is prevented from being lowered.

  The pair of bearing portions 125 and 126, the grindstone shaft 111, the first grindstone 42, and the like constitute the first grindstone holding means 123.

  The second grindstone holding means 124 provided on the second side surface 122 of the swivel base 23 is also configured similarly to the first grindstone holding means 123 described above, and the second grindstone 43 held by the second grindstone holding means 124 is ground. It is held at a position where the turning center of the swivel base 23 (the rotation center of the turning shaft 22) coincides with the surface S orthogonal to the surface 43a. In other words, in the first and second grindstones 42 and 43, the directions of the grinding resistances F1 and F2 generated when the workpiece W is ground by the first and second grindstones 42 and 43 are centered on the pivot shaft 22. It is arranged so as to face, and the turning resistance around the turning shaft 22 is prevented from being generated on the turntable 23 by the grinding resistances F1 and F2.

  The grindstone shaft 112 held by the second grindstone holding means 124 is rotated via a belt transmission device 156 by a grindstone shaft drive motor 155 installed on the swivel base 23.

  In the present embodiment, truing by the truing device 68 on the first and second grindstones 42 and 43 is performed on the grinding surface of the grinding wheel for finish grinding used for finish grinding of the first and second grindstones 42 and 43. This is performed when the detection result of the detecting means for detecting the state becomes a threshold value for determining that the state of the grinding surface of the finish grinding wheel has reached the limit state. The threshold for judging that the state of the grinding surface of the grinding wheel for finish grinding has reached the limit state is the threshold when the state of the grinding surface of the grindstone used for finish grinding in the second embodiment is in the limit state. It is set based on the wobbling amount of the grindstone. That is, as the workpiece W is ground by the first and second grindstones 42 and 43, uneven grinding, surface roughness, wear, etc. occur in the grinding wheel for finish grinding, and the grindstone for finish grinding. The criterion for making the use of as unsuitable is based on the amount of displacement (runout amount) of the grinding surface of the grinding wheel for finish grinding.

  The threshold value storage unit 91 that stores the threshold value is similar to that of the first embodiment.

The memory 62 is provided. Further, the displacement sensors 142 and 143 for measuring the displacement amounts (runout amounts) of the grinding surfaces 42a and 43a of the first and second grindstones 42 and 43 grind the first and second grindstones 42 and 43 on the upper surface of the swivel base 23. Each is installed facing the surface.

  When the measurement results of the displacement sensors 142 and 143 reach the threshold value, the grinding machine of the second embodiment configured as described above performs truing on the grinding surface of the grindstone that has been used for finish grinding until that time. After that, the grindstone is used as a grindstone for rough grinding, and after truing with the truing device 68 on the grinding surface of the grindstone that has been used for the rough grinding until then, the grindstone is used for finish grinding. It is designed to be used as a grindstone.

  Thereby, also in the case of the grinding machine 100 of the second embodiment, the number of abrasive grains to be scraped off when performing truing times and truing can be greatly reduced, so that the overall machining cost can be reduced. It is possible to achieve the same operations and effects as the first embodiment, such as being able to reduce the overall processing time.

  In the above-described embodiment, an example in which the threshold value for determining that the state of the grinding surface of the grinding wheel for finish grinding is the limit state is set based on the number of workpieces W and the amount of wobbling of the grindstone. As described above, in addition, for example, the cumulative processing time of the grinding wheel that can be ground until the grinding surface of the grinding wheel used for finish grinding reaches the limit state, or the grinding wheel used for finish grinding. You may make it set a threshold value based on the grinding resistance which generate | occur | produces when grinding a workpiece with the said grindstone when the state of a grinding surface becomes a limit state. When the threshold is set based on the accumulated machining time of the grindstone used for finish grinding, a time measuring device such as a timer for measuring the accumulated machining time can be employed as the detecting means. Further, when setting a threshold based on the grinding resistance applied to the grindstone shaft or the workpiece, a measuring instrument such as an ammeter for measuring a current change of a motor that rotationally drives the grindstone shaft or the workpiece is used as the detection means. Can be adopted.

  It should be noted that the present invention is not limited to the above-described embodiment, and various forms can be adopted without departing from the gist of the present invention described in the claims.

1 is a plan view of a grinding machine according to a first embodiment of the present invention. It is a front view which shows the turning apparatus periphery part of the grinding machine which concerns on the 1st Embodiment of this invention. It is a control block diagram which shows the control apparatus of the grinding machine which concerns on the 1st Embodiment of this invention. It is a flowchart in the case of performing truing of a 1st grindstone and a 2nd grindstone in the 1st Embodiment of this invention. It is a timing chart which performs truing of the 1st whetstone and the 2nd whetstone in the 1st embodiment of the present invention. It is explanatory drawing which shows the change of the grinding surface accompanying use of the 1st grindstone in the 1st Embodiment of this invention. It is a top view of the grinding machine which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Grinding machine, 12 ... Workpiece table, 18 ... Grinding wheel table, 20 ... Grinding wheel turning device, 21 ... Supporting base, 22 ... Turning axis, 23 ... Turning base, 40 ... Grinding wheel base, 41, 111, 112 ... Grinding wheel axis 42 ... first grinding wheel, 42a ... grinding surface, 43 ... second grinding wheel, 43a ... grinding surface, 45 ... motor for driving the grinding wheel shaft, 60 ... numerical control device, 67 ... truing tool, 68 ... truing device, 71 ... X Axis servo motor, 75... Z axis servo motor, 91... Threshold storage unit, 92 .. counter (detection means), 93... Control program (control means), 125, 126 ... bearing portions, 142 and 143.

Claims (7)

In a grinding machine comprising a plurality of grindstones, rough grinding a workpiece with any one of the plural grindstones, and finishing grinding the workpiece with any other grindstone,
A threshold value storage unit for storing a threshold value for determining that the state of the grinding surface of the grinding wheel for finish grinding used for finish grinding among the grinding stones is a limit state;
Detecting means for detecting a state of a grinding surface of the grinding wheel for finish grinding;
When the detection result of the detection means reaches the threshold value, the control means for using the grindstone as a rough grinding grindstone without performing truing on the grinding surface of the grindstone used for the finish grinding. When,
A grinding machine comprising:   2. The control means according to claim 1, wherein when the detection result of the detection means reaches the threshold value, the control means performs truing on the grinding surface of the grindstone used for the rough grinding, and then finish-grinds the grindstone. A grinding machine characterized by being used as a grinding wheel for processing. In claim 1 or claim 2, the threshold value is the number of workpieces that can be ground before the grinding surface of the grindstone used in the finish grinding process reaches the limit state.
The grinding machine according to claim 1, wherein the detecting means is a counter for counting the number of processed workpieces. In Claim 1 or Claim 2, the threshold value is a runout amount of the grindstone when the state of the grinding surface of the grindstone used for the finish grinding process is in the limit state,
The grinding machine according to claim 1, wherein the detecting means is a displacement sensor for measuring a displacement amount of the grindstone. In claim 1 or claim 2, the threshold value is a cumulative processing time of the grindstone that can be ground until the state of the grinding surface of the grindstone used for the finish grinding process reaches the limit state,
The grinding machine according to claim 1, wherein the detecting means is a time measuring device that measures a cumulative machining time of the grindstone. 3. The threshold value according to claim 1, wherein the threshold value is generated when the workpiece is ground with the grindstone when the grinding surface of the grindstone used for the finish grinding process reaches the limit state. Grinding resistance,
The grinding machine, wherein the detecting means is a measuring instrument for measuring the grinding resistance.   7. The grinding machine according to claim 1, wherein the grindstone is a CBN grindstone or a diamond grindstone.

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