JPH0220381B2 - - Google Patents

Description

Detailed Description of the Invention - Field of Industrial Application - The present invention relates to a method of dressing a grinding wheel for a centerless grinding machine and a centerless grinding machine. The present invention relates to a method of performing dressing by cutting, a so-called running dressing method, and a centerless grinding machine having a structure capable of carrying out the method.

- Conventional technology - When grinding a workpiece continuously with a centerless grinder, it is necessary to dress the grinding wheel at predetermined time intervals. The so-called "sharpening" involves forming a sharp cutting edge, and the so-called "repairing" involves restoring the grinding wheel surface, which has deviated from its normal shape due to wear, to its normal shape.
It is carried out for the purpose of When high machining accuracy is required, such as in the case of finish grinding of a workpiece, the machining of the workpiece is temporarily stopped at predetermined time intervals and the grinding wheel is dressed during that time.
In cases where such precision is not required, such as rough grinding, so-called running dressing is used in which dressing is performed while processing the workpiece in order to increase processing efficiency.

Conventional running dressing involves continuously feeding the workpiece, making the dressing blade traverse by making the minimum cut necessary for sharpening the grinding wheel at predetermined time intervals, and at the same time giving the same amount of cut to the adjusting grinding wheel. A certain amount of feed is applied at once to absorb dimensional changes in the grinding wheel due to dressing.

That is, conventionally, as shown in Fig. 7, the dressing blade cuts and traverses, for example, 5μ at every 4-minute time interval, and during this traverse operation, the adjusting grinding wheel is adjusted to adjust the advancing amount of the dressing blade. The method was to feed the same 5μ at a time. The vertical axis in FIG. 7 is the time axis, and L indicates the time required for the dressing blade to traverse.

The cutting depth of the dressing blade shown here is 5μ,
This is the amount set as the minimum depth of cut required for sharpening the grinding wheel surface, and is usually around 5μ.

-Problems to be Solved by the Invention- However, the above conventional dressing method has two problems.

The first problem is caused by the fact that the adjusting grinding wheel is fed at once by the amount of cut of the dressing blade. In other words, while the dressing blade is traversing, the circumferential surface of the grinding wheel has a small diameter part with a sharp cutting edge and a large diameter part with a worn cutting blade, and the time required for the traverse is reduced. It is unavoidable that the machining accuracy of the workpieces passing through the equipment during L (varies greatly depending on the size of the workpieces, but in general, several dozen workpieces pass through the machine) will be lowered. Because the wheel is fed all at once, there is a large variation in machining dimensions before and after the wheel is fed, and when the adjustment grinding wheel is fed, the workpiece that is in the middle of passing is further partially polished by the workpiece that sparked out. As a result, the behavior becomes unstable, resulting in a problem that the roundness and straightness are greatly reduced.

The second problem is that in the conventional method described above, the amount of cutting of the dressing blade per predetermined time period is limited. In other words, when dressing a grinding wheel, it is necessary to give the dressing blade at least the amount of cut necessary to remove worn abrasive grains and sharpen, but it is not enough to make only the amount of cut necessary for sharpening. It is common that a worn grinding wheel cannot be repaired satisfactorily. In order to modify the circumferential shape of the grinding wheel, it is necessary to make a larger cut with the dressing blade, but this will further reduce the dimensional accuracy of the workpiece that passes through it during dressing, so in the end it is necessary to make the minimum cut. Dressing has to be carried out by giving As a result, in conventional grinding using a running dress, although some parts of the grinding wheel are sharpened, there are still parts that are not sharpened, and the shape of the grinding wheel surface is not perfect. I was worried.

The reason why the running dressing method as shown in Fig. 7 was conventionally adopted is that in conventional centerless grinding machines, a ratchet mechanism using hydraulic pressure as the driving source for the cutting mechanism of the dressing blade and the feeding mechanism of the adjusting grinding wheel was used. This is because it was not possible to finely control the cutting depth of the dressing blade and the adjustment grinding wheel.

The present invention aims to solve the problems of the conventional means described above.

-Means for solving the problem- In order to solve the above-mentioned first problem, in the method described in claim 1 of the present invention, the first problem is solved.
As shown in the figure, make a predetermined amount of cut F on the dressing blade.
A method is adopted in which the adjustment grinding wheel is fed in several stages n, the final feeding amount of which matches the cutting amount F of the dressing blade, while L is traversing the grinding wheel surface.

Furthermore, in the method described in claim 2 of the present invention, in order to solve the second problem mentioned above, as shown in FIG. The operation of traversing the grinding wheel surface by giving
A dressing method is adopted in which the multiple cutting and traversing operations of the dressing blade are repeated at predetermined time intervals T.

The above-mentioned dressing method cannot be carried out in a centerless grinding machine having a structure in which the cutting mechanism of the dressing blade and the feeding mechanism of the adjusting grinding wheel are performed by a ratchet mechanism using hydraulic pressure as a driving source. Therefore, in claim 3 of the present invention, the cutting mechanism of the dressing blade 42 and the feeding mechanism of the adjusting grinding wheel 3 are rotationally driven by electric motors 47 and 33 such as pulse motors and servo motors whose rotation angle can be controlled. It has a structure in which the dressing bar 41 and the adjusting grindstone head 31 are driven by ball screws 48 and 34, and the number of divided feeds n of the adjusting grinding wheel 3 during the traverse L of the dressing blade 42 is continuous.
The present invention discloses a centerless grinding machine equipped with a control device that can set the number N of repetitions of the cutting and traversing operations (2) and the time interval T for performing these repetitive operations.

-Operation- According to the method recited in claim 1 of the present invention, the adjusting grinding wheel 3 is divided into n stages and sent into the traverse L of the dressing blade 42.
The amount of feed f, f _o per time is much smaller than that in the conventional method, and therefore, it is possible to reduce fluctuations in the machining dimensions of the workpiece before and after the feed of the adjusting grinding wheel 3. Furthermore, since the feeding amount of the adjusting grinding wheel 3 is small, the effect on the workpiece that is currently being ground during this feeding is small, and the behavior of the workpiece will not become unstable and the machining accuracy of the workpiece will not be greatly reduced.

Further, according to the method recited in claim 2 of the present invention, the above-mentioned effect is achieved, and the dressing blade 42 continuously grinds the grinding wheel N times with the minimum cutting amount F necessary for sharpening the grinding wheel surface. Since the surface is dressed, it is possible to completely dress the entire surface of the whetstone and modify the surface by dressing the surface multiple times, and the cutting depth F of the dressing blade each time is the minimum required for dressing. , it is possible to avoid an increase in dimensional fluctuations of the workpiece passing through the device during dressing.

Further, with the configuration as set forth in claim 3 of the present invention, it is possible to obtain a centerless grinding machine that can continuously grind a workpiece while automatically carrying out the above-mentioned dressing method.

-Example- Fig. 3 schematically shows the overall configuration of a centerless grinder according to the present invention, in which 1 is a bed, 2 is a grinding wheel, 3 is an adjustment wheel, and 4 is a grinding wheel. It is a dressing device. The grinding wheel 2 is pivotally attached to a casing 21 fixed to the bed 1, and the dressing device 4 is attached to the casing 21 via a movable table 5 that is intermittently driven back and forth in a direction perpendicular to the plane of the drawing. 51 is an electric motor for driving the moving table 5.

11 is a lower slide stand provided on the bed; 1
2 is an upper slide stand provided on the lower slide stand 11 so as to be slidable in the left-right direction in the figure; 31 is an upper slide stand 1;
2 is the adjustment whetstone head fixed, 32 is the adjustment whetstone head 3
The adjusting grinding wheel 3 is a casing of an adjusting grinding wheel substantially integral with the adjusting grinding wheel 32, and the adjusting grinding wheel 3 is pivoted to this casing 32. 13 is a drive casing fixed to the rear end of the lower slide table 12, and this drive casing has a ball screw 34 driven by a pulse motor 33.
is pivoted in a cantilever manner, and this ball screw 34 is screwed onto the adjustment grindstone head 31.

FIG. 4 shows the detailed structure of the dressing device 4, in which the moving table 5 is mounted on rails 52, 52 fixed to the casing 21 via linear rolling bearings 53, 53, and the electric motor 51 It is screwed into a driven feed screw 54. 55 is a rail provided on the movable table 5 in the horizontal direction in the figure; 41 is a dressing bar; 42 is a dressing blade at the tip of the dressing bar; 43 is a copying casing; 44 is a copying head extending downward from the copying casing 43; 56 is a casing 21
This is a fixed template. The copying casing 43 and the dress bar 41 are movably mounted on a rail 55 via linear rolling bearings 45, 45 and 46, 46, and a ball screw 48 driven by a pulse motor 47 is attached to the copying casing 43 with a cantilever shaft. It is worn and screwed onto the dress bar 41. The copying head 44 is pressed against the template 56 by a compression spring 58 interposed between a bracket 57 extending from the movable table 5, and the grinding wheel 2
is dressed into a shape according to template 56.

FIG. 5 shows an outline of the control device for the pulse motors 33, 47 and the electric motor 51, and 6 is a
7 is a memory, 8a to 8c are interface circuits, and 9a to 9c are drive circuits.
The memory 7 stores the cutting amount F of the dressing blade 42, the retreat amount B of the dressing blade 42, the number of consecutive repetitions N ₀ of the cutting of the dressing blade 42 and the traverse of the movable table 5, and the time when the dressing blade 42 starts traversing. A memory for storing each set value of the waiting time t ₀ from 0 to the start of feeding of the adjusting grinding wheel 3, the feeding cycle t of the adjusting grinding wheel, the number of times n ₀ of feeding the adjusting grinding wheel 3, and the time interval T for performing the dressing operation. A storage area is provided for The numbers shown with unit symbols in parentheses next to the symbols indicating each setting value in the figure indicate specific numerical values of each setting value as an example. Then, F/n ₀ is calculated from the above setting value, the integer part is stored as the feed amount f of the adjusting wheel, and F-(f×(n ₀ -1)) is the amount of feed of the adjusting wheel. This is stored as the final feed amount _fo .

FIG. 6 is a flowchart showing the control procedure for the pulse motors 33, 47 and electric motor 51 based on the above set values. The running dress operation of the present invention will be explained below with reference to FIG.

When a running dress is commanded, the program first sets a counter N to a set value _N0 for the number of times the continuous operation of the dressing blade 42 is repeated in step 61. Next, after waiting for the time interval T of the dressing operation, in step 62, the dressing blade 42 is advanced by the set value F of the cutting amount, and the electric motor 51 is driven to start the traverse operation of the dressing blade 42. Then, the divided number of feeds n ₀ of the adjusting grinding wheel 3 is set in a counter n, and after waiting for the waiting time t ₀ of the adjusting grinding wheel 3 for the first time, the adjusting grinding wheel 3
is advanced by the feeding amount f, and 1 is subtracted from the counter n. Thereafter, the adjusting grinding wheel 3 is fed to f at a period of t, and the final feeding amount is made to match the cutting amount F of the dressing blade 42 by setting the feeding amount to f ₀ at the first rotation. After that, when the traverse operation of the dressing blade 42 is completed, the dressing blade 42 is moved backward by B, and the electric motor 51 is reversed in rapid forward motion to return the movable table 5 to the home position.
, and subtracts 1 from the counter N.

Then, the operations from step 62 onwards are repeated continuously until the counter N becomes 0. When the counter N becomes 0, the process returns to step 61 and enters the standby operation for the time interval T again, and when the time interval T has elapsed, ,
The operations from step 62 onwards are performed.

The line diagram in Figure 2 is a line showing the operations of the dressing blade 42 and the adjusting grinding wheel 3 performed by the above control when the numerical values in parentheses in Figure 5 are given as set values, with the vertical axis as the time axis. In the figure, the dressing blade 42 is
The grinding wheel 2 is dressed twice in succession with a cutting depth of 5μ, and during one traverse operation L of the dressing blade 42 (approximately 30 seconds), the adjustment grinding wheel 3 is stepped in five steps with a cutting depth of 1μ. It is shown that it will be sent.

The diagram in FIG. 1 shows the dressing blade 4 in the above device.
This figure shows the operation of the dressing blade 42 and the adjusting grinding wheel 3 when the number N of consecutive repetitions of the incision and traverse in 2 is set to 1, and corresponds to the method described in claim 1 of the present invention. It is something to do. Since the operation in this figure can be easily understood from the above explanation, the explanation will be omitted.

-Effects of the invention- As understood from the description of the above-mentioned operation section,
According to the method of the present invention, fluctuations in the machining dimensions and deterioration of roundness and straightness of the workpiece during running dressing in a centerless grinding machine can be avoided, and machining accuracy can be greatly improved. It is possible to improve the machining efficiency. Further, according to the centerless grinder of the present invention, it is possible to process a workpiece while automatically implementing the running dress method of the present invention, and the processing accuracy during grinding with the running dress blade is high.
Moreover, there is an effect that a centerless grinding machine with excellent processing efficiency can be provided.

[Brief explanation of drawings]

The drawings are diagrams showing an embodiment of the present invention, in which FIG. 1 is an operational diagram illustrating the method described in claim 1, and FIG. 2 is an operational diagram illustrating the method described in claim 2. , Figure 3 is an overall side view of the centerless grinder, Figure 4
The figure is a side view of the dressing device for a grinding wheel, FIG. 5 is a block diagram of the control device, FIG. 6 is a flowchart showing the control procedure of the control device, and FIG. 7 is an operation diagram showing the conventional running dressing method. It is. In the figure, F: Setting value of the cutting amount of the dressing blade,
N ₀ : Number of continuous repetitions of cutting and traversing operations of the dressing blade, L: Traverse period of the dressing blade, n ₀ : Number of divided feeds of the adjusting grinding wheel during the traversing period of the dressing blade, T: Time interval of the dressing operation , 2: Grinding wheel, 3: Adjusting grinding wheel, 3
1: Adjustment grindstone head, 33: Pulse motor, 34: Ball screw, 41: Dress bar, 42: Dress blade,
47: Pulse motor, 48: Ball screw, 5: Moving table, 51: Moving table driving electric motor, 6: CPU,
7: Memory.

Claims (1)

[Scope of Claims] 1. A running dressing method for a centerless grinding machine in which the dressing blade cuts a certain amount at predetermined time intervals while processing a workpiece and traverses the grinding wheel surface to sharpen and modify the grinding wheel surface. , a centerless grinding machine characterized in that, while the dressing blade traverses the grinding wheel surface, a feed whose final feed amount matches the cutting amount of the dressing blade is divided into multiple times and applied to the adjusting grinding wheel. How to dress for running. 2. A claim that causes the dressing blade to perform the operation of making the above-mentioned cut by a certain amount and traverse the grinding wheel surface multiple times in succession, and repeating the multiple cutting and traversing operations of the dressing blade at predetermined time intervals. The running dress method according to item 1. 3. The cutting mechanism of the dressing blade and the feeding mechanism of the adjusting grinding wheel are constituted by a mechanism including a ball screw driven by an electric motor whose rotation angle can be controlled, and the control of the electric motor is performed by dividing the adjusting grinding wheel during traverse of the dressing blade. means for setting the number of feedings;
A centerless grinding machine characterized in that the grinding is performed by a control device including means for setting the number of consecutive repetitions of the cutting operation and traverse operation of the dressing blade, and means for setting the time interval for performing the repetitive operation.