JP2019130612A - Plane grinding method of workpiece and double-head plane grinder - Google Patents

Abstract

To further efficiently and accurately grind a workpiece which is composed of a complex material of hard grains and a metal base material by using a pair of grinding stones.SOLUTION: When plane-grinding a workpiece 6 composed of a complex material 3 of hard grains 1 and a metal base material 2 by using a pair of grinding stones 7, 8, at least the grinding stone 7 out of the pair of grinding stones 7, 8 is intermittently cut at a constant time interval T by a constant cut-in amount D. The constant cut-in amount D is an amount at which the grinding stone 7 can grind the workpiece 6 within a constant time, and can perform only spark-out grinding prior to succeeding cut-in. As the grinding stones 7, 8, used is a grinding stone whose grain size ratio A/B of an average abrasive grain size A of the grinding stones 7, 8 and grain sizes B of the hard grains 1 of the workpiece 6 is a proper grain size ratio.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a surface grinding method and a double-sided surface grinding machine for grinding a workpiece made of a composite material of hard particles and a base material with a grinding wheel.

  A composite material 3 of diamond grains 1 and a metal base material 2 may be used for a heat dissipation member. For example, as shown in FIG. 13A, the composite material 3 includes diamond grains 1 and a metal base material 2 that holds the diamond grains 1. For the metal base material 2, a soft metal material having a Vickers hardness of about 20 to 150, such as silver or copper, is used.

  When a workpiece made of such a composite material 3 is ground, it is necessary to finish the ground surface 4 smoothly without dropping the diamond particles 1 on the ground surface, as shown in FIG. This is because the diamond grain 1 on the grinding surface side falls off during grinding of the workpiece, or the metal base material 2 around the diamond grain 1 is worn away, so that the grinding surface 4 of the workpiece after grinding is shown in FIG. If it becomes uneven | corrugated as shown in FIG. 3, it is because a clearance gap will be made between a heat radiating member and an attachment site | part, the heat transfer efficiency to a heat radiating member will fall, and the heat dissipation effect will worsen.

  In general, the infeed / oscillate method is employed when the workpiece as the composite material 3 is subjected to surface grinding with a grinding wheel such as a metal bond diamond wheel using a surface grinding machine. In this case, the surface grinding method includes a continuous grinding method (see FIG. 14) in which the grinding wheel is continuously cut at a predetermined speed, and an intermittent cutting method in which the grinding wheel is intermittently cut while alternately moving forward and backward. There is a grinding method (Patent Document 1).

  As shown in FIG. 14, the continuous grinding method continuously cuts the grinding wheel at a constant cutting speed V1 along a predetermined continuous cutting characteristic E3 while measuring the change in the load current I1. The point at which the current I1 rises above the set value I2 is defined as a cutting speed change point P. From the cutting speed change point P, the speed is reduced from the cutting speed V1 to the cutting speed V2, and the cutting speed V2 is reached. This is a grinding method in which the workpiece is continuously cut until a predetermined finished size is obtained.

  The intermittent grinding method is a grinding method in which the grinding wheel is intermittently cut until the workpiece has a predetermined finished size while alternately repeating the forward movement and the backward movement of the grinding wheel with respect to the workpiece.

JP 2001-225249 A

  In the conventional continuous grinding method, since the grinding wheel is continuously cut into the workpiece, the chips of the workpiece adhere to the abrasive grains of the grinding wheel and the sharpness of the grinding wheel is lowered. As a result, the grinding load increases, and as shown in FIG. 13 (c), the diamond particles 1 on the grinding surface side of the workpiece fall off, or the metal base material 2 around the diamond particles 1 is worn away to form the diamond particles 1. There is a problem that the ground surface 4 cannot be ground with high accuracy.

  On the other hand, the intermittent grinding method grinds the workpiece while the grinding wheel repeats forward and backward alternately, so that coolant can easily enter the gap between the grinding wheel and the workpiece, and chips can be discharged quickly. There is an advantage that the sharpness can be improved and the ground surface can be ground smoothly and with high precision. However, in this intermittent grinding method, the grinding time during which the grinding wheel cannot directly participate in grinding of the workpiece accounts for about half of the total time from the start of grinding to the end of grinding. There are disadvantages that the cycle time becomes very long and the grinding efficiency of the workpiece is lowered.

  In view of such conventional problems, the present invention provides a workpiece surface grinding method and double-sided surface grinding capable of efficiently and accurately grinding a workpiece made of a composite material of hard grains and a metal base material with a pair of grinding wheels. The purpose is to provide a board.

In the surface grinding method for a workpiece according to the present invention, when a workpiece made of a composite material of hard particles and a metal base is surface ground with a pair of grinding wheels, at least one of the pair of grinding wheels is fixed at regular intervals. Step cutting is performed by intermittently cutting a certain amount of cutting.

  The constant cutting amount is preferably less than the maximum grinding amount that the grinding wheel can grind the workpiece within a predetermined time. The step incision preferably has a spark-out grinding or grinding pause before the next constant infeed amount. As the grinding wheel, it is desirable to use a grinding wheel having an appropriate ratio of the average grain size of the abrasive grains of the grinding wheel and the hard grains of the workpiece.

  When using a grinding wheel whose depth of cut is not known, this calculation is performed by proportionally calculating the depth of cut with respect to the particle size ratio of the grinding wheel based on the known grain size ratio and depth of cut of the grinding wheel. It is desirable to set the cut depth as the upper limit cut depth of the grinding wheel. The particle size ratio of the grinding wheel is desirably in a range in which hard particles of the workpiece do not fall off during grinding.

  The double-sided surface grinder for a workpiece according to the present invention is configured to grind at least one grinding wheel of a pair of grinding wheels at a constant time interval when a workpiece made of a composite material of hard grains and a metal base material is ground by the pair of grinding wheels. And step cutting control means for performing step cutting intermittently by a predetermined cutting amount.

  According to the present invention, when grinding a workpiece with a pair of grinding wheels, step cutting is performed in which at least one of the pair of grinding wheels is intermittently cut by a fixed cutting amount at fixed time intervals. There is an advantage that a workpiece made of a composite material of a metal base material can be efficiently and precisely ground.

1 is a schematic view of a vertical double-head surface grinding machine showing a first embodiment of the present invention. It is explanatory drawing of the grinding state. It is a figure which shows the relationship between the movement of the grinding wheel, and load current. It is explanatory drawing of the step cutting. It is explanatory drawing of the cut amount. It is a figure which shows the relationship between the grinding and load current. It is a figure which shows the relationship between the grindstone count and average abrasive grain diameter. It is a figure which shows the relationship between the grindstone count and particle size ratio. It is a figure which shows the grinding result. It is a figure which shows the relationship between the grindstone count and the cutting upper limit amount. It is a block diagram of a control system showing a second embodiment of the present invention. It is the same flowchart. It is explanatory drawing of a composite material and a grinding state. It is a figure which shows the relationship between the motion of the grinding wheel of the conventional grinding method, and load current.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 10 illustrate a first embodiment of the present invention. FIG. 1 shows a schematic view of a vertical double-head surface grinding machine 5. As shown in FIG. 1, this vertical double-head surface grinding machine 5 has a pair of upper and lower grinding wheels 7 and 8 that grind the workpiece 6 from both the upper and lower sides, and is attached to and detached from the opposite ends of the grinding wheels 7 and 8. The grinding wheel shafts 9 and 10 are mounted in a vertical direction. The vertical double-sided surface grinding machine 5 employs an in-feed / oscillate system, and grinds the upper and lower surfaces of the workpiece 6 with a pair of upper and lower grinding wheels 7 and 8.

  As the grinding wheels 7 and 8, metal bond diamond wheels are used. As shown in FIG. 2, the grinding wheels 7 and 8 are composed of diamond abrasive grains 18 and a grindstone base material (metal bond material) 19 that holds the diamond abrasive grains 18. The work 6 is a composite material 3 of diamond grains 1 and a metal base material 2.

  The grinding wheels 7 and 8 are detachably attached to opposite ends of the grinding wheel mounting bases 11 and 12 fixed to the grinding wheel shafts 9 and 10. The grindstone shafts 9 and 10 are rotatably arranged on the same vertical axis, and can be rotated around the vertical axis by driving of the grindstone shaft drive motors 13 and 14. It is possible to move up and down by driving.

  In order to perform the step cutting, the control device of the feed drive motor 15 that drives the upper grinding wheel 7 in the feeding direction includes a step cutting control means 17 that controls the step cutting operation of the upper grinding wheel 7. Is provided. The step cutting control means 17 is for controlling the step cutting of the upper grinding wheel 7 by stopping and driving the feed drive motor 15, and the upper grinding wheel 7 grinds the upper surface side of the workpiece 6. In a series of grinding operations from the start of grinding starting to the end of grinding when the workpiece 6 has a predetermined finished size and the upper and lower grinding wheels 7 and 8 finish grinding the workpiece 6, at regular time intervals T. The feed drive motor 15 is configured to be controlled in accordance with the step cutting characteristic E so as to repeat step cutting in which the upper grinding wheel 7 is intermittently cut into the workpiece 6 by a constant cutting amount D.

  As shown in FIG. 3, the step cutting characteristic E includes a stop step E1 for stopping the cutting of the upper grinding wheel 7 for a fixed time interval T, and a cutting step for cutting the upper grinding wheel 7 by a fixed cutting amount D. A one-step operation is configured with E2 as a set, and the stop step E1 and the cutting step E2 are alternately repeated at a constant time interval T for each step operation.

  Accordingly, the step cutting control means 17 stops the cutting step E1 in which the upper grinding wheel 7 stops cutting at every fixed time interval T, and the upper grinding wheel 7 cuts by a predetermined cutting amount D at every fixed time interval T. The upper grinding wheel 7 is controlled so as to perform step cutting that alternately repeats the cutting step E2. Therefore, the pair of upper and lower grinding wheels 7 and 8 grind the upper and lower surfaces of the workpiece 6 at substantially the same amount substantially simultaneously, so that the grinding surface of the workpiece 6 can be efficiently and accurately ground.

  When the upper grinding wheel 7 is cut at a constant time interval T of 1 second, the upper and lower grinding wheels 7 and 8 can grind the workpiece 6 in one second of the stop time of the stop step E1. The amount of grinding is less than the maximum grinding amount, and is set so that a time during which grinding can be performed with light load spark-out grinding or in a state close thereto (hereinafter referred to as spark-out grinding) between the grinding and the next cutting step E2 is set. Yes.

  Incidentally, when the workpiece 6 made of the composite material 3 of the diamond particle 1 having a particle size B = 20 μm and the metal base material 2 is subjected to surface grinding with the grinding stones 7 and 8 made of a metal bond diamond grinding stone having a grinding stone count # 400, For reasons described later, it is desirable that the fixed time interval T = 1 second and the fixed cutting depth D = 1.0 μm.

  In the case of the conventional case shown in FIG. 14, it takes 4 seconds to grind 4 μm. With reference to this, in the step cutting of FIG. 3, a constant time interval T = 1 second. And a constant cutting depth D = 1.0 μm. Moreover, the fixed time interval T and the fixed cutting amount D are concepts including substantially fixed values in a range that can be equated to a fixed value in addition to the fixed value as written. The rotation directions of the upper and lower grinding wheels 7 and 8 may be the same direction or the opposite directions.

  Further, in order to simplify the explanation in FIG. 3, it is assumed that the cutting operation of the upper grinding wheel 7 in the cutting step E2 is performed instantaneously, and the stop time of the upper grinding wheel 7 is set to a fixed time in the stop step E1. It is the same as the interval T. However, even though it is practically negligible, if the cutting operation of the upper grinding wheel 7 requires a very short time t, the stop time at the stop step E1 is T−t.

  When the upper and lower surfaces of the workpiece 6 are ground using a pair of upper and lower grinding wheels 7 and 8 made of a metal bond diamond grinding wheel, the lower grinding wheel 8 is held at a predetermined advance position. In this state, the upper and lower grinding wheels 7, 8 are rotated around the grinding wheel shafts 9, 10, and the upper grinding wheel 7 is intermittently cut by a constant cutting amount D at regular time intervals T. Grind with in-feed oscillating method while doing.

  When grinding the workpiece 6, first, as shown in FIG. 1, the lower grinding wheel 8 is stopped at the forward grinding position of a predetermined height and positioned in the vertical direction, and then the upper grinding wheel 7 is not buffered with the workpiece 6. Move to position. In this state, the upper and lower grinding wheels 7 and 8 are rotated around the grinding wheel shafts 9 and 10. Then, the workpiece 6 is inserted between the upper and lower grinding wheels 7 and 8. When the insertion of the workpiece 6 is completed, the upper grinding wheel 7 is rapidly fed to the grinding start position at the air cut speed.

  Then, after the upper grinding wheel 7 has moved to the grinding start position, the upper grinding wheel 7 is advanced from the grinding start position at a predetermined grinding speed, and the direction along the grinding wheel surface between the grinding wheels 7, 8. The upper and lower surfaces of the workpiece 6 are ground by the upper and lower grinding wheels 7 and 8 while the workpiece 6 is moved back and forth.

  During grinding of the workpiece 6 by the grinding wheels 7 and 8, step cutting is performed to cut the upper grinding wheel 7 in accordance with the step cutting characteristic E under the control of the step cutting control means 17. In this step cutting, a stop step E1 in which the upper grinding wheel 7 stops cutting every predetermined time interval T = 1 second according to the step cutting characteristic E, and a cutting step for cutting by a constant cutting amount D = 1.0 μm. E2 is alternately repeated, and the upper grinding wheel 7 is intermittently cut into the workpiece 6 by a constant cutting amount D = 1.0 μm every predetermined time interval T = 1 second. As a result, the upper and lower grinding wheels 7 and 8 simultaneously grind the upper and lower surfaces of the workpiece 6, and the upper and lower surfaces of the workpiece 6 can be efficiently and accurately ground.

  That is, as shown in FIGS. 1 and 4, the upper grinding wheel 7 is intermittently cut by D1, D2, D3... And a constant cutting interval D = 1.0 μm every fixed time interval T = 1 second. When cutting is performed, the distance between the pair of upper and lower grinding wheels 7 and 8 is reduced by 1.0 μm for each step cutting. As a result, the upper and lower grinding wheels 7 and 8 are simultaneously cut into the workpiece 6 by 0.5 μm from both the upper and lower sides, and the upper and lower grinding surfaces of the workpiece 6 can be simultaneously ground by 0.5 μm.

  In this way, if a step cutting is employed in which the upper grinding wheel 7 is intermittently cut by a constant cutting amount D = 1.0 μm every fixed time interval T = 1 second, the grinding wheel drive motor for the grinding wheel is used. As shown in FIG. 3, the load current I1 of 13 and 14 only changes in a sawtooth shape every second on the lower side of the set value I2, and an increase in the load current I1 during grinding can be prevented.

  This is because when step cutting is performed in accordance with the step cutting characteristic E of FIG. 3, after cutting the upper grinding wheel 7 by 1.0 μm in the cutting step E2-1 as shown in FIG. 5 (b). Since the upper grinding wheel 7 is shifted to the stop step E2 where the upper grinding wheel 7 stops at the cutting position, the upper and lower grinding wheels 7 and 8 move the workpiece 6 while being accompanied by elastic deformation of the entire apparatus including the grinding wheels 7 and 8. Cut 0.5 μm from both the top and bottom sides. Therefore, as shown in FIGS. 5A and 5B, in the cutting step E2-1 in which the upper grinding wheel 7 is cut by 1.0 μm, the grinding load of the upper and lower grinding wheels 7 and 8 is the actual cutting amount = The load current I1 of the grindstone shaft drive motors 13 and 14 rises sharply by 0.5 μm (I1-1).

  However, during the stop step E1 after the cutting step E2-1, the upper grinding wheel 7 is not cut, and the grinding wheels 7 and 8 grind the workpiece 6 while elastic deformation returns as the grinding progresses. Therefore, the grinding load of the grindstone shaft drive motors 13 and 14 gradually decreases, and the load current I1 also falls in an inclined manner as the grinding load decreases (I1-2).

  If the upper and lower grinding wheels 7 and 8 are ground close to 0.5 μm and the elastic deformation of the entire apparatus is close to return, the grinding wheels 7 and 8 are sparked in a light load state until the next cutting step E2-2. In order to perform the out grinding, the subsequent load current I1 follows a substantially constant value until the next cutting step E2-2 (I1-3).

  When a fixed time interval T = 1 second of each one-step operation repeated during the step cutting is analyzed, as shown in FIG. 5, the substantial cutting by the upper and lower grinding wheels 7 and 8 within the first time T1 is performed. All the cutting / grinding is almost completed, and a time T2 for performing the spark-out grinding following the cutting / grinding is made. Therefore, as shown in FIG. 5, the load current I1 changes in a sawtooth shape from I1-1 through I1-2 to I1-3 at each step cutting. Instead of spark-out grinding, a grinding stop time may be provided.

  In this way, if the step cutting method of cutting the upper grinding wheel 7 by a constant cutting amount = 1.0 μm every certain time interval T = 1 second is adopted, the distance between the preceding and following cutting steps E2-1 and E2-2 is adopted. Can be provided with spark-out grinding. During the spark-out grinding, as shown in FIG. 2, a gap 28 is formed between the diamond abrasive grains 18 of the grinding wheels 7 and 8 and the grinding surface of the work 6, and coolant enters the gap 28. It becomes easy, and the coolant can quickly discharge the grinding debris that has entered the gap 28 between the grinding wheels 7 and 8 and the workpiece 6, thereby suppressing an increase in the grinding load.

  Therefore, the predetermined sharpness of the grinding wheels 7 and 8 can be maintained, and the predetermined grindability can be maintained, and the ground surface of the workpiece 6 can be efficiently and accurately ground. In each step operation of step cutting, since the upper and lower grinding wheels 7 and 8 repeat the spark-out grinding of the workpiece 6, there is an advantage that the finished state of the ground surface of the workpiece 6 is further improved by the spark-out grinding.

  Further, during the step cutting, the grinding wheels 7 and 8 only repeat the cutting step E2 and the stop step E1 alternately and there is no backward movement of the grinding wheels 7 and 8. There is no loss time, the grinding cycle can be shortened and grinding can be performed efficiently.

  Further, for a workpiece 6 having a diamond particle diameter B of 20 μm, a grindstone # 400 is used as the grinding wheel 7, 8, and the diamond abrasive grain 18 has an average abrasive particle diameter A = 37 μm and a diamond particle 1 Since the particle size ratio A / B with the particle size B = 20 μm is small, the diamond particles 1 on the workpiece 6 side can be prevented from falling off.

  That is, when the particle size ratio A / B between the average abrasive grain size A of the grinding wheels 7 and 8 and the grain size B of the diamond grains 1 of the workpiece 6 is increased, the grinding wheel base material 19 on the side of the grinding wheels 7 and 8 becomes diamond. The abrasive grain holding force of the diamond abrasive grains 18 on the grinding wheel 7 and 8 side is related to a plurality of factors such as the abrasive grain holding force for holding the abrasive grains 18 and the rotational force and centrifugal force of the grinding wheels 7 and 8. Since it is larger than the holding force of the diamond particles 1 on the 6 side, the diamond particles 1 of the workpiece 6 fall off during grinding.

  However, as the grinding stones 7 and 8, the grindstone of the grindstone count # 400 having an average abrasive grain diameter A = 37 μm is used, whereas the grain diameter B of the diamond grain 1 of the workpiece 6 is 20 μm. Since the diameter ratio A / B is as small as 1.85, dropping of the diamond grains 1 on the workpiece 6 side can be suppressed.

  In addition to the grindstone count # 400, there are many types of metal bond diamond grindstones such as a grindstone count # 100, # 200, # 325, # 600, # 1000, # 1200, # 1500, and the like. However, if the step cutting is employed, the workpiece 6 cannot always be efficiently and accurately ground regardless of the grindstone number of the metal bond diamond grindstone. This is because the average abrasive grain size A of the diamond abrasive grains differs depending on the grinding stone count of the metal bond diamond grinding wheel (see FIG. 6), and the grain size ratio between the average abrasive grain diameter A and the grain size B of the diamond grain 1 of the workpiece 6 is different. This is because A / B is different. In addition, the average grinding particle diameter A of each metal bond diamond grindstone of FIG. 6 referred the catalog value of the grindstone manufacturer.

  Then, the actual grinding test which grinds the actual workpiece | work 6 by step cutting using various metal bond diamond grindstones was performed, and when the conditions of step cutting were considered based on the test result, the following is shown. Obtained knowledge.

  In the actual grinding test, metal bond diamond grindstones of grindstone counts # 100, # 325, # 400, and # 1200 were used. Further, the step cutting is performed at a constant time interval T = 1 second, and the actual grinding is performed when the cutting amount is changed and the constant cutting amount D = 1.0 μm and when the constant cutting amount D = 0.1 μm. A test was performed, and the finished state of the ground surface was confirmed visually.

  The test results are as shown in FIG. In FIG. 7, the mark “◯” indicates that the finished state of the ground surface of the workpiece 6 is good, and the diamond particles 1 were not dropped on either the upper or lower ground surface of the workpiece 6. The “x” mark indicates that the finished state of the ground surface of the workpiece 6 is poor. The “−” mark indicates that an actual grinding test is not performed.

  As shown in the test results of FIG. 7, when the metal bond diamond grindstones of # 100 and # 325 are used, the workpiece 6 is obtained regardless of whether the constant cutting depth D is 1.0 μm or 0.1 μm. Grinding accuracy could not be ensured due to the large roughness of the ground surface and the problem of diamond dropout.

  On the other hand, when a metal bond diamond grindstone of # 400 is used, the finished state of the ground surface of the workpiece 6 is good regardless of whether the constant cutting depth D is 1.0 μm or 0.1 μm. It was. However, even with the same step cutting, there is a big difference in grinding time between the constant cutting depth D of 1.0 μm and 0.1 μm. From the viewpoint of grinding efficiency, it is more efficient to cut with the constant cutting depth D = 1.0 μm. It turned out to be the target. Furthermore, when the metal bond diamond grindstone with a grindstone count of # 1200 was used, the finished state of the ground surface of the workpiece 6 was good when the constant cutting depth D was 0.1 μm.

  According to this test result, when the workpiece 6 is the composite material 3 having a diamond particle diameter B of 20 μm, a metal bond diamond grindstone with a grindstone count # 400 or more is used, and a constant time interval T = 1 second. It was found that the step cutting with the constant cutting amount D = 1.0 μm may be performed at any point of grinding accuracy and grinding efficiency.

  Next, the reason is considered. First, with respect to the metal bond diamond grinding stones # 325, # 400, and # 1200 used in the actual grinding test, the grain size ratio A / of the average abrasive grain size A and the grain size B of the diamond grain 1 of the workpiece 6 is 20 μm. Consider the relationship between B and the quality of the ground surface of the workpiece 6.

  Since the average abrasive grain size A of the metal bond diamond grinding stones of the grinding wheel counts # 325, # 400, and # 1200 is as shown in FIG. 6, the grain size ratio A / B of the grinding stone count # 325 is 2.20. The particle size ratio A / B of # 400 is 1.85, and the particle size ratio A / B of the grindstone count # 1200 is 0.65. The relationship between the grindstone counts # 325, # 400, and # 1200 having these particle size ratios A / B and the quality of the ground surface of the workpiece 6 is as shown in FIG.

  Looking at the relationship between the grain size ratio A / B of each grinding wheel count and the quality of the grinding surface of the workpiece 6, the grain size ratio A / B of grinding stone count # 325 is 2.20, and the grinding surface finish of the workpiece 6 is finished. The condition was bad. On the other hand, the particle size ratio A / B of the grinding wheel count # 400 is 1.85, the particle size ratio A / B of the grinding wheel count # 1200 is 0.65, and the finished state of the ground surface of the workpiece 6 is good. Met. In this case, the particle size ratio A / B is less than 2.

  From the test results shown in FIG. 8, when the workpiece 6 grinds the composite material 3 with the diamond particle size B = 20 μm, the workpiece number is higher than the grindstone count # 400 with the particle size ratio A / B = 1.85. It has been found that a metal bond diamond wheel with a large number (small particle size ratio A / B) should be used.

  This is because the holding power of the diamond abrasive grains 18 is increased when the grain size ratio A / B of the average abrasive grain diameter A of the diamond abrasive grains 18 and the grain diameter B of the diamond grains 1 is increased as in the grinding stone count # 325. This is because the diamond grain 1 on the grinding surface is easily dropped off due to the excessive holding force of the diamond grain 1 on the grinding surface 6 and the finished state is lowered.

  Therefore, when the workpiece 6 is the composite material 3 having a diamond particle diameter B of 20 μm, the particle diameter ratio A / B of the metal bond diamond grindstone used is 2.20 of the grindstone count # 325. The diamond grains of the workpiece 6 during grinding, such as being less than about 2 (or 2 or less) in the middle of the grain size ratio 1.85 of the grinding wheel count # 400, preferably about 185 or less, preferably the grain size ratio of the grinding wheel count # 400. It is necessary to keep it within a range where 1 does not fall off.

  Next, with respect to the grindstone counts # 325 and # 400 used in the actual grinding test, the relationship among the particle size ratio A / B, the cutting amount, the quality of the grinding surface, the number of cuttings, and the actual grinding time is shown in FIG. For convenience of explanation, the number of cuttings and the actual grinding time were calculated with the total grinding amount being 10 μm.

  When the metal bond diamond grindstone was the grindstone count # 325, the finished state of the ground surface of the workpiece 6 was poor regardless of whether the constant cutting depth D was 1.0 μm or 0.1 μm. This is because the particle size ratio A / B = 2.20 is large, so that the diamond particles 1 on the ground surface of the workpiece 6 easily fall off regardless of the size of the constant cutting depth D.

  When the metal bond diamond grindstone was a grindstone count # 400, the finished state of the ground surface was good regardless of whether the constant cutting depth D was 1.0 μm or 0.1 μm. This is because the particle size ratio A / B = 1.85 is appropriate, so that the diamond grains 1 on the ground surface of the workpiece 6 can be prevented from falling off regardless of the size of the constant cutting depth D. These are as described above.

  However, although the finished state of the ground surface is good, when step cutting is performed with a constant cutting amount D = 1.0 μm, the number of cuttings until the total grinding amount of 10 μm is ground is 10 times. While efficient grinding is possible with an actual grinding time of 10 seconds, when step cutting is performed with a constant cutting amount D = 0.1 μm, the number of cuttings until the total grinding amount of 10 μm is ground is 100. Thus, an actual grinding time of 100 seconds is required, and the grinding efficiency is greatly reduced.

  From the result of this actual grinding test, when the workpiece 6 is a composite material 3 having a diamond particle diameter B of 20 μm, the particle diameter ratio A / B is less than 2 (or less than 2), preferably the particle diameter ratio. When using a metal bond diamond grindstone with A / B = 1.85 or less, the constant cutting depth D must be excessively large relative to the grinding amount of the metal bond diamond grindstone and the total grinding amount of the workpiece 6. For example, it has been found that a predetermined grinding accuracy is ensured regardless of the size of the constant cutting depth D. Therefore, as long as the metal bond diamond grindstone itself satisfies the condition of the particle size ratio A / B, in the step cutting, the constant cutting amount D to be cut at every constant time interval T can be appropriately determined in consideration of the grinding efficiency. Good.

  In addition, the relationship between the fixed time interval T and the fixed cutting amount D in the step cutting is relatively determined by the relationship with the sharpness of the metal bond diamond grindstone, and the sharpness varies depending on the grindstone count. Since the particle size ratio A / B differs depending on the type, it is necessary to determine the difference in consideration.

  When the workpiece 6 is a composite material 3 having a diamond particle size B = 20 μm, a metal bond diamond wheel # 400 having a particle size ratio A / B = 1.85 is used from the result of an actual grinding test. Then, it has been found that step cutting may be performed with a constant cutting amount D = 1.0 μm every certain time interval T = 1 second.

  The constant depth of cut D is an important condition that affects the grinding efficiency. Even when the particle size ratio A / B = 1.85 or less is satisfied, the value of the constant depth of cut D depends on the metal bond diamond grindstone. to differ greatly. Therefore, when it is necessary to use another metal bond diamond grindstone whose constant cut amount D is not known (for example, a grindstone with a grinding wheel count # 600), a constant cut amount D suitable for the metal bond diamond grindstone is obtained. Therefore, it is necessary to change the constant cutting amount D at the time of step cutting to the value.

  In such a case, it may be calculated by the following method. That is, for example, when the constant cutting depth D of the metal bond diamond grindstone of the grindstone count # 600 is not known, the average abrasive grain size A (= 30 μm) can be found from the description in the catalog or the like. From the particle diameter B of the diamond grains 1 (= 20 μm), the particle diameter ratio C6 (= A / B) of the metal bond diamond grindstone for which the cutting depth Y should be calculated first can be determined.

  On the other hand, if the workpiece 6 is ground using a metal bond diamond grindstone of # 400, the grinding efficiency and grinding performance are both good, and the particle size ratio A / B = 1.85 is known. Therefore, the metal bond diamond grindstone of the grindstone count # 400 is used as a standard grindstone. Then, the particle size ratio A / B = 1.85 of the grindstone count # 400 is set to an appropriate particle size ratio C4, and the constant cut amount D = 1.0 μm is set to an appropriate cut amount D4. The cutting amount D6 of the metal bond diamond grindstone is calculated proportionally according to the ratio of the particle size ratio C4 and the particle size ratio C6 of the grinding wheel count # 600 (D6 = C6 · D4 / C4). D6 is set as the cutting upper limit amount D6max (= constant cutting amount D) when using the metal bond diamond grindstone of # 600 grindstone.

  Incidentally, the cutting upper limit amount of the metal bond diamond grindstones of the grindstone counts # 400, # 600, # 1000, # 1200, and # 1500 are as shown in FIG.

  In this way, every time the metal bond diamond wheel to be used changes, it is not necessary to confirm the constant cutting amount D of the metal bond diamond wheel by an actual grinding test, and the workpiece 6 can be set up quickly before grinding. There are advantages. Further, since the workpiece 6 can be ground with a cutting upper limit suitable for the metal bond diamond grindstone, the grinding efficiency can be improved.

  11 and 12 illustrate a second embodiment of the present invention. In this embodiment, as shown in FIG. 11, the setting means 20 for setting conditions such as the grindstone count, the grain size B of the diamond grains 1 of the workpiece 6, and the step cutting based on the conditions set by the setting means 20 The calculation means 21 for calculating the particle size ratio A / B and the cutting upper limit amount Dmax, which are the cutting control conditions, and the cutting upper limit amount Dmax calculated by the calculation means 21 as the constant cutting amount D at every constant time interval T And a step cutting control means 17 for controlling the drive motor 15 so as to cut the grinding wheel 7 intermittently.

  The setting means 20 includes a grindstone count setting unit 22 that sets the grindstone count, and a particle size setting unit 23 that sets the particle size B of the diamond grains 1 of the workpiece 6. The calculating means 21 calculates the particle size ratio A between the grindstone count grindstone and the workpiece 6 from the grindstone count set by the grindstone count setting unit 22 and the particle size B of the diamond grain 1 set by the particle size setting unit 23. Particle size ratio calculating unit 24 for calculating / B, and suitability determination for determining whether or not the grindstone of the grindstone count is appropriate for the workpiece 6 from the particle size ratio A / B calculated by the particle size ratio calculating unit 24 When the unit 25 and the suitability determination unit 25 determine that the grindstone is appropriate, the constant time interval T at the time of step cutting of the grindstone from the particle size ratio A / B calculated by the particle size ratio calculation unit 24 When the cutting time interval calculating unit 26 and the suitability determining unit 25 determine that the grindstone is suitable, the cutting upper limit Dmax of the grindstone with the particle size ratio A / B calculated by the particle size ratio calculating unit 24 is calculated. Is proportional based on the appropriate particle size ratio C4 and the appropriate cutting depth D4 of the standard grindstone stored in advance. And a cutting limit calculation unit 27 for calculating the.

  The step cutting control means 17 starts the grinding of the workpiece 6 in accordance with the fixed time interval T calculated by the cutting time interval calculating unit 26 and the fixed cutting amount D calculated by the cutting upper limit amount calculating unit 27. The feed drive motor 15 is controlled so that the grindstone is intermittently cut into the workpiece 6 by a constant cutting amount D every fixed time interval T until grinding is completed. In addition, when the suitability determination unit 25 determines that the grindstone is unsuitable, it is informed by a not-shown informing means to prompt the change of the grindstone count and the like.

  In this embodiment, processing from setting to the end of grinding is performed through the process shown in FIG. First, each setting is performed by the setting means 20 before the grinding of the workpiece 6 is started, and the condition for the step cutting control is automatically calculated by the calculation means 21. Then, unless the condition set by the setting means 20 is changed, such as changing to another type of grindstone or workpiece 6, the step cutting control means 17 performs step cutting control according to the calculation result of the calculation means 21, and sequentially The workpiece 6 is ground under the in-feed oscillating method.

  In the setting means 20, the grindstone count used for grinding the workpiece 6 is set by the grindstone count setting unit 22 (S1), and the particle size B of the diamond particle 1 of the workpiece 6 to be ground is set by the particle size setting unit 23. (S2), it is determined whether or not all the conditions have been set (S3).

  If all the conditions have been set, the particle size ratio calculation unit 24 calculates the particle size ratio A / between the diamond abrasive grains 18 of the grinding wheel and the diamond grains 1 of the workpiece 6 from the grindstone count and the particle diameter B of the diamond grains 1. B is calculated (S4). Next, whether or not the particle size ratio A / B calculated by the particle size ratio calculation unit 24 is less than 2 (or 2 or less), preferably 1.85 or less, is used for grinding the workpiece 6. It is determined whether or not the set grinding wheel count is appropriate (S5).

  If the particle size ratio A / B exceeds 1.85, the grindstone is inappropriate for the workpiece 6, and this is notified to prompt the exchange of the grindstone and the process is terminated (S6). If the particle size ratio A / B is equal to or less than 1.85, it is determined that the grindstone of the grindstone is suitable for grinding the workpiece 6 (S5), and the cutting time interval calculation unit 26 uses the grindstone with the grindstone count of the work 6 A fixed time interval T for grinding is calculated (S7). In this case, the cutting time interval may be changed corresponding to each particle size ratio A / B, or it may be a constant time (for example, 1 second) regardless of the size of the particle size ratio A / B. It is also possible.

  Next, the cutting upper limit amount calculation unit 27 is proportional to the cutting upper limit amount Dmax with respect to the workpiece 6 in the case of the particle size ratio A / B calculated by the particle size ratio calculation unit 24, with the grindstone of # 400 as the standard grindstone. (S8).

  When all the calculations are completed, a grinding start command is waited (S94), and the step cutting control means 17 applies the grinding wheel to the workpiece 6 by a fixed cutting amount D at a fixed time interval T through the feed drive motor 15. Step cutting control for intermittent cutting is performed (S10). Then, the step cutting control is continued until the workpiece 6 has a predetermined finished dimension (S10, S11). When the workpiece 6 has a predetermined finished dimension (S11), the grinding of the workpiece 6 by the step cutting control is finished.

  In this way, by setting the grindstone count of the grindstone used for grinding the workpiece 6 and the grain size B of the diamond grains 1 of the workpiece 6, the computation of the grain size ratio A / B, the grain size ratio A / Step cutting for determining whether B is appropriate, calculating a fixed time interval T, calculating a cutting upper limit Dmax, etc., and intermittently cutting the grindstone with respect to the work 6 by a fixed cutting amount D at a fixed time interval T. Control can be executed automatically.

  As mentioned above, although each embodiment of this invention was explained in full detail, this invention is not limited to this embodiment, A various change is possible. For example, in the embodiment, the case of the vertical double-sided surface grinder 5 provided with a pair of upper and lower grinding wheels 7 and 8 is illustrated, but the horizontal double-headed surface grinder provided with a pair of grinding wheels 7 and 8 on the left and right. But it can be done in the same way.

  In the embodiment, in the vertical double-sided surface grinder 5, step cutting control is illustrated in which the upper grinding wheel 7 is intermittently cut by a constant cutting amount D at a constant time interval T. Of the grindstones 7 and 8, the lower grinding wheel 8 may be intermittently cut by a constant cutting amount D at a constant time interval T, or both the upper and lower grinding wheels 7 and 8 may be simultaneously cut at a constant time interval. You may make it cut intermittently by fixed cutting amount D / 2 by T. However, when both the grinding wheels 7 and 8 are cut simultaneously, it is desirable that the constant cutting amount D of each grinding wheel 7 and 8 is approximately half that of the case where the grinding wheel 7 or the grinding stone 8 on one side is cut. . The same applies to a horizontal double-sided surface grinder.

  In the embodiment, the composite material 3 in which the grain size B of the diamond grains 1 is 20 μm is illustrated as the workpiece 6, but the composite material 3 including hard grains other than the diamond grains 1 can be similarly implemented. The hard particles may be natural materials or artificial materials that are harder than the metal base material 2. Therefore, it is sufficient for the composite material 3 to include the diamond particles 1 or hard particles including other natural materials or artificial materials, and the soft metal base material 2 that holds the hard particles. The grinding wheels 7 and 8 may be other than metal bond diamond wheels.

  In the embodiment, since the grinding result when the composite material 3 having the diamond particle size B of 20 μm was ground with the grindstone of the grindstone count # 400 having the average abrasive grain size A of 37 μm was good, the grindstone of the grindstone count # 400 was used. As a standard grindstone, the cutting upper limit amount Dmax of the grindstone of another grindstone count is calculated based on the standard grindstone.

  However, when the workpiece 6 which is the composite material 3 other than the diamond particle diameter B of 20 μm is ground with the grinding stones 7 and 8 of the metal bond diamond grindstone other than the average abrasive particle diameter A of 37 μm, the composite material is used. A standard grindstone may be determined from the combination of the particle diameter B of the diamond particle 1 of 3 and the average grindstone diameter A of the metal bond diamond grindstone of the grindstone count. Therefore, the standard grindstone is not limited to the grindstone count # 400.

  When grinding a workpiece 6 having a low surface roughness, a metal bond diamond grindstone other than the grindstone count # 400, for example, a metal bond diamond grindstone such as a grindstone count # 1000 or # 1500 is used as the grinding wheels 7 and 8. By doing so, it is also possible to grind the workpiece 6 efficiently. In this case, a metal bond diamond grindstone such as a grindstone count # 1000 or # 1500 may be a standard grindstone.

  Further, when the grinding wheels 7 and 8 are stepped, the fixed time interval T, the constant cutting amount D, and the cutting upper limit amount are the average grinding particle size A of the grinding wheel and the grain size B of the diamond grains of the workpiece 6. And is not limited to the numerical values of the embodiments.

  In the embodiment, the cutting upper limit amount Dmax of the grinding wheels 7 and 8 is obtained, and the constant cutting amount D (appropriate cutting amount) when cutting the grinding wheels 7 and 8 into the workpiece 6 is described as the cutting upper limit amount Dmax. However, the constant cutting amount D for actually grinding the workpiece 6 may be a cutting amount D slightly smaller than the cutting upper limit amount Dmax as the appropriate cutting amount X.

1 Diamond grains (hard grains)
2 Metal base material 3 Composite material 6 Work piece 7 and 8 Grinding wheel 9 and 10 Grinding wheel shaft 13 and 14 Grinding wheel shaft drive motor 15 and 16 Feeding drive motor 17 Step cutting control means 18 Diamond abrasive grain 19 Grinding wheel base material 20 Setting Means 21 Calculation means 22 Grinding wheel count setting unit 23 Particle size setting unit 24 Particle size ratio calculation unit 26 Cutting time interval calculation unit 27 Cutting upper limit amount calculation unit T Constant time interval D Constant cutting amount A Average abrasive grain size B grain Diameter

Claims (7)

  When surface grinding a workpiece made of a composite material of hard grains and a metal base with a pair of grinding wheels, step cutting is performed by intermittently cutting at least one of the pair of grinding wheels by a constant cutting amount at regular time intervals. A surface grinding method for a workpiece, characterized in that the grinding is performed.   2. The surface grinding method for a workpiece according to claim 1, wherein the constant cutting amount is less than a maximum grinding amount with which the grinding wheel can grind the workpiece within a predetermined time.   3. The method of surface grinding of a workpiece according to claim 1, wherein the step cutting has a spark-out grinding or a grinding pause before the next constant cutting amount.   4. The grinding wheel according to claim 1, wherein the grinding wheel has an appropriate particle size ratio between the average grain size of the abrasive grains of the grinding wheel and the grain size of the hard grains of the workpiece. Surface grinding method for workpieces.   When using a grinding wheel whose depth of cut is not known, this calculation is performed by proportionally calculating the depth of cut with respect to the particle size ratio of the grinding wheel based on the known grain size ratio and depth of cut of the grinding wheel. The method for surface grinding of a workpiece according to any one of claims 1 to 4, wherein the cut depth is set as a cut upper limit amount of the grinding wheel.   The method of surface grinding of a workpiece according to any one of claims 1 to 5, wherein the particle size ratio of the grinding wheel is within a range in which hard particles of the workpiece do not fall off during grinding.   When cutting a workpiece made of a composite material of hard particles and a metal base material with a pair of grinding wheels, step cutting is performed by intermittently cutting at least one of the pair of grinding wheels by a constant cutting amount at regular time intervals. A double-sided surface grinding machine for workpieces, comprising step cutting control means for carrying out setting.