JP6909739B2 - Work surface grinding method and double-headed surface grinding machine - Google Patents

Description

The present invention relates to a surface grinding method and a double-headed surface grinding machine for a work in which a work made of a composite material of hard grains and a base material is surface-ground with a grinding wheel.

A composite material 3 of a diamond grain 1 and a metal base material 2 may be used as a heat radiating member. As shown in FIG. 13A, for example, the composite material 3 is composed of a diamond grain 1 and a metal base material 2 holding the diamond grain 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 grinding a work made of such a composite material 3, as shown in FIG. 13B, it is necessary to finish the ground surface 4 in a smooth shape without dropping the diamond grains 1 on the ground surface. This is because the diamond grain 1 on the ground surface side falls off during the grinding of the work, or the metal base material 2 around the diamond grain 1 is worn away, so that the ground surface 4 of the work after grinding is shown in FIG. 13 (c). This is because if the surface is uneven as shown in the above, a gap is formed between the heat radiating member and the mounting portion, the heat transfer efficiency to the heat radiating member is lowered, and the heat radiating effect is deteriorated.

When a workpiece made of such a composite material 3 is surface-ground using a surface grindstone and a grinding wheel such as a metal bond diamond grindstone, an in-feed oscillating method is generally adopted. 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 grinding method in which the grinding wheel is intermittently cut while alternately repeating the forward and backward movements of the grinding wheel. There is a grinding method (Patent Document 1).

In the continuous grinding method, as shown in FIG. 14, the grinding wheel is continuously cut at a constant cutting speed V1 along a predetermined continuous cutting characteristic E3 while measuring the change in the load current I1, and the load is applied. The time when the current I1 rises above the set value I2 is set as the cutting speed change point P, and after that cutting speed change point P, the cutting speed is decelerated from the cutting speed V1 to the cutting speed V2, and the cutting speed V2 is used. This is a grinding method in which the workpiece is continuously cut until it reaches a predetermined finished size.

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

Japanese Unexamined Patent Publication No. 2001-225249

In the conventional continuous grinding method, since the grinding wheel is continuously cut into the work, the chips of the work 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 grain 1 on the grinding surface side of the work falls off, or the metal base material 2 around the diamond grain 1 is worn away to form the diamond grain 1. There is a problem that the ground surface 4 cannot be ground smoothly and with high accuracy due to protrusion.

On the other hand, in the intermittent grinding method, since the grinding wheel grinds the workpiece while alternately repeating forward and backward, coolant easily enters the gap between the grinding wheel and the workpiece, and chips can be quickly discharged. There is an advantage that the sharpness of the grindstone is improved and the ground surface can be ground smoothly and with high accuracy. However, in this intermittent grinding method, of the total time from the start of grinding to the end of grinding, the ungrindable time during which the grinding wheel cannot directly participate in the grinding of the workpiece occupies about half of the total time. There is a drawback that the cycle time becomes very long and the grinding efficiency of the workpiece decreases.

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

Surface grinding method for a work according to the present invention, when a work made of a composite material of the hard particles and the base metal to surface grinding by a pair of grinding wheels, a predetermined time at least one of the grinding wheel of the pair of grinding wheels There lines intermittently cutting step cuts by a constant depth of cut at intervals, wherein in step cutting has a cutting step of cutting by a constant depth of cut at regular time intervals during said predetermined time after said cutting step The work is spark-out ground during each of the stop steps after the constant cut amount is cut and before the next cut step by alternately repeating the stop step for stopping the cut .

It said predetermined depth of cut is preferably the grinding wheel within a predetermined time period is less than the maximum amount of grinding grinding possible the work. The grinding wheel is preferably the particle size ratio between the particle diameter of the hard particles of the workpiece the average abrasive grain size of the abrasive grains of the grinding whetstone is used as the proper range.

When using a grinding wheel whose depth of cut is unknown, the depth of cut is calculated proportionally to the particle size ratio of the grinding wheel based on the known particle size ratio and cutting amount of the grinding wheel. It is desirable that the depth of cut is the upper limit of the depth of cut of the grinding wheel. It is desirable that the particle size ratio of the grinding wheel is within a range in which the hard particles of the work do not fall off during grinding.

Double head surface grinding machine the workpiece according to the present invention, when surface grinding of hard grains and a metal matrix and a pair of grinding wheels workpieces made of composite material, at least one of the grinding wheel of the pair of grinding wheels A step cutting control means for intermittently making a step cutting by a fixed cutting amount at regular time intervals is provided, and the step cutting control means has a fixed cutting amount at regular intervals during the step cutting. The cutting step for cutting and the stop step for stopping the cutting within the fixed time after the cutting step are alternately repeated, and each of the stopping steps after cutting the constant cutting amount and before the next cutting step. It has a control function for spark-out grinding the work inside .

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 regular time intervals. There is an advantage that a work made of a composite material of a metal base material and a metal base material can be efficiently ground with high accuracy.

It is the schematic of the vertical double-headed surface grinding machine which shows the 1st Embodiment of this invention. It is explanatory drawing of the same grinding state. It is a figure which shows the relationship between the movement of the grinding wheel and a load current. It is explanatory drawing of the step cut. It is a figure which shows the relationship between the grinding and a load current. It is a figure which shows the relationship between the grindstone count and the average grindstone particle diameter. It is a figure which shows the actual grinding result by the difference of the grindstone count. It is a figure which shows the relationship between the grindstone count and a 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 the control system which shows the 2nd Embodiment of this 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 movement of the grinding wheel of the conventional grinding method, and a load current.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 10 illustrate the first embodiment of the present invention. FIG. 1 shows a schematic view of a vertical double-headed surface grinding machine 5. As shown in FIG. 1, the vertical double-headed surface grinding machine 5 is attached to and detached from a pair of upper and lower grinding wheels 7 and 8 for grinding the work 6 from both upper and lower sides, and to the end side where the respective grinding wheels 7 and 8 face each other. It has vertically mounted grindstone shafts 9 and 10. The vertical double-headed surface grinding machine 5 employs an in-feed oscillating method to grind both the upper and lower surfaces of the work 6 with a pair of upper and lower grinding wheels 7 and 8.

Metal-bonded diamond grindstones are used for the grinding wheels 7 and 8. 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 the diamond grain 1 and the metal base material 2.

The grinding wheels 7 and 8 are detachably attached to the opposite ends of the grindstone mounting bases 11 and 12 fixed to the grindstone 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 the grindstone shaft drive motors 13 and 14, and the feed drive motors 15 and 16 It can move up and down by driving.

In order to perform the step cutting, the control device of the feed drive motor 15 for driving the upper grinding wheel 7 in the feed direction is provided with the step cutting control means 17 for controlling 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 work 6. In a series of grinding operations from the start of grinding to the end of grinding where the work 6 has a predetermined finished size and the upper and lower grinding wheels 7 and 8 finish grinding the work 6, at regular time intervals T The feed drive motor 15 is configured to be controlled according to the step cutting characteristic E so as to repeat the step cutting in which the upper grinding wheel 7 is intermittently cut into the work 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 by 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 set to be alternately repeated at regular time intervals T for each step operation.

Therefore, in the step cutting control means 17, the upper grinding wheel 7 cuts in the stop step E1 at which the cutting is stopped at regular time intervals T, and the upper grinding wheel 7 cuts by a fixed cutting amount D at regular time intervals T. The upper grinding wheel 7 is controlled so as to perform step cutting in which the cutting step E2 is alternately repeated. Therefore, the pair of upper and lower grinding wheels 7 and 8 grind the upper and lower surfaces of the work 6 by substantially the same amount at the same time, and the grinding surface of the work 6 can be efficiently ground with high accuracy.

With the constant depth of cut D, when the upper grinding wheel 7 is cut at a fixed time interval T of 1 second, the upper and lower grinding wheels 7 and 8 can grind the work 6 within 1 second of the stop time of the stop step E1. be less than the maximum grinding amount, the grinding and subsequent grinding with light load spark-out grinding or a state close to that of between the cutting step E2 (hereinafter, referred to as spark-out grinding) is by Uni set Ru can.

Incidentally, when a work 6 made of a composite material 3 of a diamond grain 1 having a particle size B = 20 μm and a metal base material 2 is surface-ground with a grinding wheel 7 or 8 made of a metal-bonded diamond grindstone having a grindstone count # 400, For the reasons described later, it is desirable that the constant time interval T = 1 second and the constant depth of cut D = 1.0 μm.

In the conventional case shown in FIG. 14, it takes 4 seconds to grind 4 μm. Therefore, referring to this, in the step cutting in FIG. 3, the fixed time interval T = 1 second. The constant depth of cut D = 1.0 μm. Further, the constant time interval T and the constant depth of cut D are concepts that include not only constant as the wording, but also substantially constant within a range that can be equated with constant. Further, the rotation directions of the upper and lower grinding wheels 7 and 8 may be the same direction or may be opposite directions.

Further, in FIG. 3, for simplification of the description, it is assumed that the cutting operation of the upper grinding wheel 7 in the cutting step E2 is performed instantaneously, and the stopping time of the upper grinding wheel 7 in the stop step E1 is set to a fixed time. It is the same as the interval T. However, in reality, if the cutting operation of the upper grinding wheel 7 requires an extremely short time t, although it is practically negligible, the stop time in the stop step E1 is Tt.

When using this double-headed surface grindstone 5 to grind both the upper and lower surfaces of the work 6 with a pair of upper and lower grinding wheels 7 and 8 made of metal-bonded diamond grindstones, the lower grinding wheel 8 is held in a predetermined forward position. In this state, the upper and lower grinding wheels 7 and 8 are rotated around the grindstone shafts 9 and 10, and the upper grinding wheel 7 is intermittently cut by a fixed cutting amount D at regular time intervals T. While doing this, grind with the in-feed oscillating method.

When grinding the work 6, first, as shown in FIG. 1, the lower grinding wheel 8 is stopped at a 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 work 6. Move to the position. In that state, the upper and lower grinding wheels 7 and 8 are rotated around the grindstone shafts 9 and 10. Then, the work 6 is inserted between the upper and lower grinding wheels 7 and 8. When the insertion of the work 6 is completed, the upper grinding wheel 7 is fast-forwarded 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 at a predetermined grinding speed from the grinding start position, and the direction along the grinding wheel surface between the grinding wheels 7 and 8. While reciprocating the work 6, both the upper and lower surfaces of the work 6 are ground by the upper and lower grinding wheels 7 and 8.

During grinding of the work 6 by the grinding wheels 7 and 8, step cutting is performed to cut the upper grinding wheel 7 according to 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 at regular time intervals T = 1 second according to the step cutting characteristic E, and a cutting step in which a constant cutting amount D = 1.0 μm is cut. E2 and E2 are alternately repeated, and the upper grinding wheel 7 is intermittently cut into the work 6 by a constant cutting amount D = 1.0 μm at regular time intervals T = 1 second. As a result, the upper and lower grinding wheels 7 and 8 grind both the upper and lower surfaces of the work 6 at the same time, and the upper and lower surfaces of the work 6 can be efficiently ground with high accuracy.

That is, as shown in FIGS. 1 and 4, the upper grinding wheel 7 is intermittently cut into D1, D2, D3 ... And a constant cutting amount D = 1.0 μm at regular time intervals T = 1 second. When the cutting is performed, the interval between the pair of upper and lower grinding wheels 7 and 8 is reduced by 1.0 μm for each step of cutting. As a result, the upper and lower grinding wheels 7 and 8 are cut at the same time by 0.5 μm from both the upper and lower sides with respect to the work 6, and the grinding surfaces on both the upper and lower sides of the work 6 can be ground by 0.5 μm at the same time.

In this way, if step cutting is adopted in which the upper grinding wheel 7 is intermittently cut by a fixed cutting amount D = 1.0 μm at regular time intervals T = 1 second, a drive motor for the grinding wheel shaft by a grinding load is adopted. As shown in FIG. 3, the load currents I1 of 13 and 14 only change in a sawtooth shape every second below the set value I2, and an increase in the load current I1 during grinding can be prevented.

This is because, when performing step cutting according to the step cutting characteristic E in FIG. 3, after cutting 1.0 μm of the upper grinding wheel 7 in cutting step E2-1 as shown in FIG. 5 (b). Since the upper grinding wheel 7 shifts to the stop step E2 in which the grinding wheel 7 stops at the cutting position, the work 6 is moved while the upper and lower grinding wheels 7 and 8 are elastically deformed in the entire device including the grinding wheels 7 and 8. Cut 0.5 μm from both the upper and lower 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 drive motors 13 and 14 for the grindstone shaft 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 work 6 while the elastic deformation returns as the grinding progresses. to execute, gradually small no longer grinding load wheel spindle drive motor 13 and 14, the load current I1 also falls to the inclined shape with decreasing the grinding load (I1-2).

If the upper and lower grinding wheels 7, 8 Re return the elastic deformation of the entire 0.5μm near ground to the apparatus, the spark-out grinding the grinding wheel 7 and 8 in a light load state until the next cutting step E2-2 After that, the load current I1 follows a substantially constant value until the next cutting step E2-2 (I1-3).

When the fixed time interval T = 1 second of each one-step operation repeated during the step cutting is analyzed, as shown in FIG. 5, the actual cutting by the upper and lower grinding wheels 7 and 8 is performed within the first time T1. All of the indentation and grinding are almost completed, and the time T2 for spark-out grinding is provided following the incision and grinding. Therefore, as shown in FIG. 5, the load current I1 changes from I1-1 to I1-2 in a serrated manner at each step cut. In addition, instead of spark-out grinding, a grinding pause time may be provided.

By adopting the step cutting method in which the upper grinding wheel 7 is cut at regular time intervals T = constant cutting amount = 1.0 μm every 1 second, between the front and rear cutting steps E2-1 and E2-2. Can be provided with spark-out grinding. Then, 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 the coolant enters the gap 28. The coolant facilitates the process, and the grinding debris that has entered the gap 28 between the grinding wheels 7 and 8 and the work 6 can be quickly discharged, and an increase in the grinding load can be suppressed.

Therefore, it is possible to maintain a predetermined sharpness of the grinding wheels 7 and 8 and a predetermined grindability, and it is possible to efficiently grind the ground surface of the work 6 with high accuracy. Since the upper and lower grinding wheels 7 and 8 repeat the spark-out grinding of the work 6 in each step operation of the step cutting, there is an advantage that the finished state of the ground surface of the work 6 is further improved by the spark-out grinding.

Further, during the step cutting, the grinding wheels 7 and 8 only alternately repeat the cutting step E2 and the stopping step E1 and there is no backward operation of the grinding wheels 7 and 8, so that between the start of grinding and the end of grinding. There is no loss time, the grinding cycle can be shortened, and grinding can be performed efficiently.

Further, a grindstone with a grindstone count # 400 is used as the grinding wheels 7 and 8 for the work 6 having a particle size B of the diamond grain 1 of 20 μm, and the average abrasive grain size A of the diamond abrasive grains 18 is 37 μm and the diamond grain 1 is used. Since the particle size ratio A / B with the particle size B = 20 μm is small, it is possible to suppress the diamond grain 1 on the work 6 side from falling off.

That is, if the particle size ratio A / B between the average abrasive grain size A of the grinding wheels 7 and 8 and the particle size B of the diamond grains 1 of the work 6 becomes large, the grindstone base material 19 on the grinding wheels 7 and 8 side becomes diamond. Multiple 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 are related, and the abrasive grain holding force of the diamond abrasive grains 18 on the grinding wheels 7 and 8 side works. Since it is larger than the holding force of the diamond grain 1 on the 6 side, the diamond grain 1 of the work 6 falls off during grinding.

However, as the grinding wheels 7 and 8, a grindstone with an average grinding wheel diameter A = 37 μm and a grindstone count # 400 is used, whereas the grain size B of the diamond grain 1 of the work 6 is 20 μm, and both grains. Since the diameter ratio A / B is as small as 1.85, it is possible to prevent the diamond grain 1 on the work 6 side from falling off.

In addition to the grindstone count # 400, there are many types of metal-bonded diamond grindstones such as grindstone counts # 100, # 200, # 325, # 600, # 1000, # 1200, and # 1500. However, if step cutting is adopted, it is not always possible to efficiently grind the work 6 with high accuracy regardless of which grindstone count metal bond diamond grindstone is used. This is because the average abrasive grain size A of the diamond abrasive grains differs depending on the grindstone count of the metal-bonded diamond grindstone (see FIG. 6), and the particle size ratio between the average abrasive grain size A and the grain size B of the diamond grain 1 of the work 6 This is because the A / B are different. For the average abrasive particle size A of each metal-bonded diamond grindstone in FIG. 6, the catalog value of the grindstone manufacturer was referred to.

Therefore, using various metal-bonded diamond grindstones, an actual grinding test was conducted to grind the actual work 6 by step cutting, and the conditions for step cutting were considered based on the test results. I got the knowledge.

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

The test results are as shown in FIG. In FIG. 7, the “◯” mark indicates that the finished state of the ground surface of the work 6 is good, and no diamond grain 1 was found to fall off on either the upper or lower ground surface of the work 6. The “x” mark indicates that the finished state of the ground surface of the work 6 is poor. The "-" mark indicates that the actual grinding test has not been performed.

As shown in the test results of FIG. 7, when the metal-bonded diamond grindstones having grindstone counts # 100 and # 325 are used, the work 6 is used regardless of whether the constant depth of cut D is 1.0 μm or 0.1 μm. Due to the large surface roughness of the ground surface and the problem of diamond grains falling off, the grinding accuracy could not be ensured.

When a metal-bonded diamond grindstone with a grindstone count # 400 is used, the finished state of the ground surface of the work 6 is good regardless of whether the constant depth of cut D is 1.0 μm or 0.1 μm. rice field. However, even with the same step cutting, there is a large difference in grinding time between 1.0 μm and 0.1 μm with a constant cutting amount D, and from the viewpoint of grinding efficiency, it is more efficient to cut with a constant cutting amount D = 1.0 μm. It turned out to be the target. Further, when a metal bond diamond grindstone with a grindstone count # 1200 was used, the finished state of the ground surface of the work 6 was good when the constant depth of cut D was 0.1 μm.

According to this test result, when the work 6 is a composite material 3 having a grain size B of diamond grains 1 of 20 μm, a metal-bonded diamond grindstone having a grindstone count of # 400 or more is used and a fixed time interval T = 1 second. It was found that step cutting with a constant cutting amount D = 1.0 μm is good in terms of both grinding accuracy and grinding efficiency.

Next, the reason will be considered. First, for the metal-bonded diamond grindstones with grindstone counts # 325, # 400, and # 1200 used in the actual grinding test, the grain size ratio A / of the average grindstone grain size A and the grain size B of the diamond grain 1 of the work 6 = 20 μm. Consider the relationship between B and the quality of the finished state of the ground surface of the work 6.

Since the average grain size A of the metal-bonded diamond grindstones of the grindstone counts # 325, # 400, and # 1200 is as shown in FIG. 6, the grain size ratio A / B of the grindstone count # 325 is 2.20, and the grindstone count 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 work 6 is as shown in FIG.

Looking at the relationship between the particle size ratio A / B of each grindstone count and the quality of the ground surface of the work 6, the particle size ratio A / B of the grindstone count # 325 is 2.20, and the finished surface of the work 6 is finished. The condition was bad. On the other hand, the particle size ratio A / B of the grindstone count # 400 is 1.85, the particle size ratio A / B of the grindstone count # 1200 is 0.65, and the finished state of the ground surface of the work 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 work 6 grinds the composite material 3 having a particle size B = 20 μm of the diamond grain 1, it has a count higher than that of the grindstone count # 400 having a particle size ratio A / B = 1.85. It was found that a large number of metal-bonded diamond grindstones (with a small particle size ratio A / B) should be used.

This is because if the particle size ratio A / B of the average abrasive particle size A of the diamond abrasive grains 18 and the particle size B of the diamond grains 1 becomes as large as the grindstone count # 325, the holding force of the diamond abrasive grains 18 works. This is because the holding force of the diamond grain 1 on the ground surface of No. 6 becomes too large, so that the diamond grain 1 on the ground surface is likely to fall off and the finished state is deteriorated.

Therefore, when the work 6 is a composite material 3 having a diamond grain 1 particle size B = 20 μm, the particle size ratio A / B of the metal-bonded diamond grindstone used is 2.20, which is the grain size ratio of the grindstone count # 325. Diamond grains of work 6 during grinding, such as keeping the grain size ratio of grindstone # 400 to less than about 2 (or 2 or less), which is intermediate between the grain size ratio of 1.85, and preferably to about 1.85 or less of the grain size ratio of grindstone # 400. It is necessary to keep 1 within the range where it does not fall off.

Next, with respect to the grindstone counts # 325 and # 400 used in the actual grinding test, the relationship between the particle size ratio A / B, the depth of cut, the quality of the ground surface, the number of cuts, and the actual grinding time is shown in FIG. For convenience of explanation, the number of cuts and the actual grinding time were calculated assuming that the total grinding amount was 10 μm.

When the metal-bonded diamond grindstone had a grindstone count # 325, the finished state of the ground surface of the work 6 was poor regardless of whether the constant depth of cut D was 1.0 μm or 0.1 μm. This is because the particle size ratio A / B = 2.20, which is large, makes it easy for the diamond grains 1 on the ground surface of the work 6 to fall off regardless of the size of the constant depth of cut D.

When the metal-bonded diamond grindstone had a grindstone count # 400, the finished state of the ground surface was good regardless of whether the constant depth of cut D was 1.0 μm or 0.1 μm. This is because since the particle size ratio A / B = 1.85 is appropriate, it is possible to prevent the diamond grains 1 on the ground surface of the work 6 from falling off regardless of the size of the constant depth of cut 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 can be performed with an actual grinding time of 10 seconds, when step cutting is performed with a constant depth of cut D = 0.1 μm, the number of cuts until the total grinding amount of 10 μm is ground is 100. This is the number of times, and the actual grinding time of 100 seconds is required, which greatly reduces the grinding efficiency.

From the results of this actual grinding test, when the work 6 is a composite material 3 having a diamond grain 1 particle size B = 20 μm, the particle size ratio A / B = less than 2 (or 2 or less), preferably the particle size ratio. When using a metal-bonded diamond grindstone with A / B = 1.85 or less, the constant depth of cut D at one time must be excessively large with respect to the grinding amount of the metal-bonded diamond grindstone and the total grinding amount of the work 6. For example, it was found that a predetermined grinding accuracy is ensured regardless of the size of the constant depth of cut D. Therefore, as long as the metal-bonded diamond grindstone itself satisfies the condition of the particle size ratio A / B, the constant depth of cut D to be cut at regular time intervals T in the step cutting may be appropriately determined in consideration of the grinding efficiency. good.

The relationship between the constant time interval T and the constant depth of cut D in the step cutting is relatively determined by the relationship with the sharpness of the metal bond diamond grindstone, and the sharpness differs depending on the grindstone count, and the type of work 6 Since the particle size ratio A / B also differs depending on the type, it is necessary to consider these differences when deciding.

When the work 6 is a composite material 3 having a grain size B of diamond grains 1 of 20 μm, a metal-bonded diamond grindstone having a grain size ratio of A / B = 1.85 and a grindstone count # 400 is used based on the test results of the actual grinding test. Then, it was found that the step cutting should be performed at a constant time interval T = every 1 second with a constant cutting amount D = 1.0 μm.

The constant depth of cut D is an important condition that affects the grinding efficiency, and even when the condition of particle size ratio A / B = 1.85 or less is satisfied, the value of the constant depth of depth D is determined by the metal bond diamond grindstone. to differ greatly. Therefore, when it becomes necessary to use another metal-bonded diamond grindstone whose constant depth of cut D is unknown (for example, a grindstone with a grindstone count # 600), a constant depth of cut D suitable for the metal-bonded diamond grindstone is obtained. Therefore, it is necessary to change the constant cutting amount D at the time of step cutting to that value.

In such a case, it may be calculated by the following method. That is, for example, when the constant depth of cut D of the metal-bonded diamond grindstone having a 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 size B (= 20 μm) of the diamond grain 1, the particle size ratio C6 (= A / B) of the metal-bonded diamond grindstone for which the depth of cut Y should be calculated can be determined.

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

Incidentally, the upper limit of cutting of the metal bond diamond grindstones of each grindstone count # 400, # 600, # 1000, # 1200, # 1500 is as shown in FIG.

In this way, every time the metal-bonded diamond grindstone to be used changes, it is not necessary to confirm the constant depth of cut D of the metal-bonded diamond grindstone in the actual grinding test, and the setup of the work 6 before grinding can be performed quickly. There are advantages. Further, when grinding the work 6, it is possible to grind with an upper limit of depth suitable for the metal-bonded diamond grindstone, so that 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 and the particle size B of the diamond grain 1 of the work 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 cut upper limit amount Dmax, which are the inclusion control conditions, and the cut upper limit amount Dmax calculated by the calculation means 21 are set as a constant cut amount D at regular time intervals T. The step cutting control means 17 for controlling the feed drive motor 15 so as to intermittently cut the grinding wheel 7 is provided.

The setting means 20 includes a grindstone count setting unit 22 for setting the grindstone count, and a particle size setting unit 23 for setting the particle size B of the diamond grain 1 of the work 6. The calculation means 21 is based on 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, and the particle size ratio A between the grindstone of the grindstone count and the work 6 From the particle size ratio calculation unit 24 that calculates / B and the particle size ratio A / B calculated by the particle size ratio calculation unit 24, the suitability judgment that determines whether or not the grindstone of the grindstone count is appropriate for the work 6. When the unit 25 and the suitability determination unit 25 determine that the grindstone of the grindstone count is appropriate, the particle size ratio A / B calculated by the particle size ratio calculation unit 24 is used to determine the fixed time interval T at the time of step cutting of the grindstone. When the cutting time interval calculation unit 26 and the suitability determination unit 25 determine that the grindstone is appropriate, the cutting limit amount Dmax of the grindstone having a particle size ratio A / B calculated by the particle size ratio calculation unit 24 Is provided with a cutting upper limit amount calculation unit 27 that calculates proportionally based on the appropriate particle size ratio C4 of the standard grindstone and the appropriate cutting amount D4 that are stored in advance.

The step cutting control means 17 starts grinding the work 6 according to the constant time interval T calculated by the cutting time interval calculation unit 26 and the constant cutting amount D calculated by the cutting upper limit amount calculation unit 27. It is configured to control the feed drive motor 15 so as to intermittently cut the grindstone into the work 6 by a constant depth of cut D at regular time intervals T until the grinding is completed. When the suitability determination unit 25 determines that the grindstone is inappropriate, it is notified by a notification means (not shown) to prompt the change of the grindstone count or the like.

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

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

If all the conditions have been set, the particle size ratio calculation unit 24 determines the particle size ratio A / of the grindstone count and the grain size B of the diamond grain 1 to the diamond abrasive grain 18 of the grindstone and the diamond grain 1 of the work 6. Calculate B (S4). Next, depending on whether the particle size ratio A / B calculated by the particle size ratio calculation unit 24 by the suitability determination unit 25 is less than 2 (or 2 or less), preferably 1.85 or less, the grinding of the work 6 is performed. It is determined whether or not the set grindstone count is appropriate (S5).

When the particle size ratio A / B exceeds 1.85, the grindstone is unsuitable for the work 6, so that the grindstone is notified to prompt the replacement of the grindstone and the process is completed (S6). If the particle size ratio A / B is 1.85 or less, it is determined that the grindstone with the grindstone count is suitable for grinding the work 6 (S5), and the cutting time interval calculation unit 26 uses the grindstone with the grindstone count to grind the work 6 Is calculated at a fixed time interval T when grinding (S7). In this case, the cutting time interval may be changed according to each particle size ratio A / B, or may be set to a uniform fixed time (for example, 1 second) regardless of the size of the particle size ratio A / B. It is also possible.

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

When all the calculations and the like are completed , the step cutting control means 17 waits for the grinding start command (S9 ), and the step cutting control means 17 uses the feed drive motor 15 to move the grindstone at regular time intervals T with a constant cutting amount D for each work 6. Step cutting control for intermittent cutting is performed (S10). Then, the step cutting control is continued until the work 6 reaches a predetermined finished dimension (S10, S11), and when the work 6 reaches a predetermined finished dimension (S11), the grinding of the work 6 by the step cutting control is completed.

By doing so, by setting the grindstone count of the grindstone used for grinding the work 6 and the particle size B of the diamond grain 1 of the work 6, the particle size ratio A / B can be calculated and the particle size ratio A / Judgment of suitability of B, calculation of fixed time interval T, calculation of cutting upper limit amount Dmax, etc. are performed, and according to this, the grindstone is intermittently cut by a fixed cutting amount D at a fixed time interval T with respect to the work 6. The built-in control can be executed automatically.

Although each embodiment of the present invention has been described in detail above, the present invention is not limited to this embodiment and various modifications can be made. For example, in the embodiment, the case of the vertical double-headed surface grinding machine 5 provided with the pair of upper and lower grinding wheels 7 and 8 is illustrated, but the horizontal double-headed surface grinding machine provided with the pair of grinding wheels 7 and 8 on the left and right is illustrated. But it can be done in the same way.

Further, in the embodiment, in the vertical double-headed surface grinding machine 5, the step cutting control in which the upper grinding wheel 7 is intermittently cut by a fixed cutting amount D at a fixed time interval T is illustrated. Of the grindstones 7 and 8, the lower grinding wheel 8 may be intermittently cut by a fixed cutting amount D at a fixed time interval T, or both the upper and lower grinding wheels 7 and 8 may be cut at a fixed time interval at the same time. It is also possible to intermittently cut by a constant cutting amount D / 2 at T. However, when cutting both grinding wheels 7 and 8 at the same time, it is desirable that the constant depth of cut D of each grinding wheel 7 and 8 is approximately half that of cutting the grinding wheel 7 or the grinding wheel 8 on one side. .. This also applies to a horizontal double-headed surface grinding machine.

In the embodiment, the composite material 3 in which the particle size B of the diamond grains 1 is 20 μm is illustrated as the work 6, but the composite material 3 containing hard grains other than the diamond grains 1 can be similarly implemented. The hard grain may be a natural material or an artificial material that is harder than the metal base material 2. Therefore, it is sufficient that the composite material 3 contains diamond grains 1 or other hard grains containing natural materials and artificial materials, and a soft metal base material 2 that holds the diamond grains 1. The grinding wheels 7 and 8 may be other than the metal bond diamond grindstone.

Further, in the embodiment, when the composite material 3 having the grain size B of 20 μm of the diamond grain 1 was ground with the grindstone of the grindstone count # 400 having the average grindstone particle size A37 μm, the grinding result was good. As a standard grindstone, the cutting upper limit amount Dmax of a grindstone with another grindstone count is calculated based on the standard grindstone.

However, when the work 6 which is a composite material 3 having a grain size B of diamond grains 1 other than the particle size B of 20 μm is ground with the grinding wheels 7 and 8 of a metal-bonded diamond grindstone having a grindstone count other than the average abrasive grain size of A 37 μm, the composite material is used. A standard grindstone may be determined from a combination of the particle size B of the diamond grain 1 of No. 3 and the average abrasive grain size A of the metal-bonded diamond grindstone having a grindstone count. Therefore, the standard grindstone is not limited to the grindstone count # 400.

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

Further, when the grinding wheels 7 and 8 are step-cut, the constant time interval T, the constant cutting amount D, and the upper limit of cutting are the average abrasive particle size A of the grinding wheel and the diamond grain size B of the work 6. It is determined by the relative relationship of, and is not limited to the numerical value of the embodiment.

In the embodiment, the upper limit of cutting 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 work 6 is described as the upper limit of cutting amount Dmax. However, as for the constant cutting amount D for actually grinding the work 6, the cutting amount D slightly smaller than the cutting upper limit amount Dmax may be set as the appropriate cutting amount X.

1 Diamond grain (hard grain)
2 Metal base material 3 Composite material 6 Work 7, 8 Grindstone 9, 10 Grindstone shaft 13, 14 Drive motor for grindstone shaft 15, 16 Drive motor for feed 17 Step cutting control means 18 Diamond abrasive grain 19 Grindstone base material 20 setting Means 21 Calculation means 22 Grindstone count setting unit 23 Grain size setting unit 24 Grain size ratio calculation unit 26 Cutting time interval calculation unit 27 Cutting upper limit amount calculation unit T Fixed time interval D Constant cutting amount A Average abrasive particle size B grains Diameter

Claims (6)

When surface grinding a work made of a composite material of hard grains and a metal base material with a pair of grinding wheels
There rows step cut to cut intermittently by a predetermined depth of cut at a predetermined time interval at least one of the grinding wheel of the pair of grinding wheels,
During the step cutting, the cutting step of cutting by a fixed cutting amount at regular time intervals and the stop step of stopping the cutting within the fixed time after the cutting step are alternately repeated.
A method for surface grinding of a work, which comprises spark-out grinding the work during each of the stop steps after the constant cut amount is cut and before the next cut step. The surface grinding method for a work according to claim 1, wherein the constant depth of cut is less than the maximum grinding amount that the grinding wheel can grind the work within a certain time. The invention according to claim 1 or 2 , wherein the grinding wheel has a particle size ratio of an average abrasive particle size of the abrasive grains of the grinding wheel and the particle size of the hard grains of the work in an appropriate range. Work surface grinding method. When using the grinding wheel whose depth of cut is unknown,
Based on the known particle size ratio and depth of cut of the grindstone, the depth of cut with respect to the particle size ratio of the grinding wheel is calculated proportionally, and this calculated depth of cut is used as the upper limit of depth of cut of the grinding wheel. The method for surface grinding of a workpiece according to any one of claims 1 to 3, wherein the work surface is ground. The surface grinding method for a work according to any one of claims 1 to 4 , wherein the particle size ratio of the grinding wheel is within a range in which hard particles of the work do not fall off during grinding. A work made of a composite material of the hard particles and the metal matrix when surface grinding by a pair of grinding wheels, at least one of the grinding wheel intermittently by a predetermined depth of cut at a fixed time interval of the pair of grinding wheels A step cut control means for making a step cut is provided.
During the step cutting, the step cutting control means includes a cutting step of cutting by a fixed cutting amount at regular time intervals and a stop step of stopping the cutting during the fixed time after the cutting step. A double-headed surface grinding machine for a work, which has a control function of spark-out grinding the work during each of the stop steps after the constant cut amount is cut and before the next cut step.

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