JPH0146267B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a cam grinding method that is mainly applied to machining engine valve camshafts, and more specifically to a cam grinding method that is applied to machining a cradle that supports a workpiece in synchronization with the workpiece. The present invention relates to a cam grinding method in which a workpiece is ground to a predetermined cam profile with a rotary grindstone while being tilted to follow the master cam by contact between a master cam and a touch roller.

(Prior art) Conventionally, as this type of grinding method,
According to Publication No. 131461, after setting the workpiece on the cradle, the cradle is tilted to a position where the master cam and the touch roller come into contact with each other while the rotation of the workpiece is stopped, and then the rotary grindstone is sent forward from the standby position and the workpiece is fixed. When the rotary grindstone advances to a predetermined cutting position and a part of the workpiece has been ground to the predetermined depth of cut, the rotary grindstone stops moving forward, and then the cradle is rotated by the master cam and the touch roller at all times. It is known that the workpiece is rotated while being biased so that the workpiece is in contact with the master cam, and thereby the cradle is tilted to follow the master cam, thereby grinding the workpiece to a predetermined cam profile.

(Problems to be Solved by the Invention) In the above-mentioned conventional technology, since grinding is started by moving the rotary grindstone forward, there are the following disadvantages.

a. In order to move the rotating grindstone, bearing box, electric motor, and the entire table on which they are placed back and forth, a large thrust is required to move them back and forth, and the sliding members also require accurate machining, making it difficult to move the grindstone forward and backward. It becomes large and expensive.

b The cradle is tilted to the position where the master cam and the tatsuchi roller come into contact, and after confirming this tilting, the grinding wheel is advanced to start grinding, and after confirming the tilting of the cradle, the grinding wheel advances to the predetermined cutting position. It usually takes 0.9sec~
It takes 1.0sec, for example, in the case of a 4-cylinder camshaft, a total of 8 cams x (0.9 to 1.0)
= Loss time of 7.2sec to 8sec occurs.

c. The work must be rotated after confirming that the grindstone has advanced to the cutting position, and a device for detecting the forward and backward movement of the grindstone table is required. Two-stage interlock control is required, including control for rotating the workpiece after confirming the forward movement, which increases the cost of the control system.

The present invention has been made in view of the above problems, and its purpose is to provide a method that can reduce equipment costs and efficiently perform cam grinding.

(Means for Solving the Problems) In order to achieve the above object, the present invention rotates the work while tilting the cradle that supports the work by following the master cam and contacting the touch roller with the master cam that rotates in synchronization with the work. In a cam grinding method in which a grindstone is used to grind a predetermined cam profile, a part of a workpiece is ground to a predetermined depth of cut by a rotary grindstone while the rotation of the workpiece is stopped at the start of grinding. A rotary whetstone is placed in advance at a prescribed cutting position on the workpiece, and the cradle is tilted with the workpiece stopped rotating until the master cam and the touch roller come into contact with each other, and during this tilting, the rotary whetstone A part of the workpiece is ground to the predetermined cutting depth, and then the workpiece is rotated and ground with the cradle being biased so that the master cam and the touch roller are always in contact with each other.

(Operation) After setting the workpiece on the cradle, in the process of tilting the cradle to a position where the master cam and the touch roller contact, a part of the workpiece is ground to a predetermined cutting depth by the rotating grindstone located at the cutting position. .

By the way, the above-mentioned tilting of the cradle has conventionally been performed at a relatively low speed to prevent damage caused by collision between the master cam and the tatsuchi roller, and even if the cradle is tilted while grinding the workpiece as in the present invention, this The time required for tilting is not much different from the conventional one, and therefore the working time is shortened by the time required for the conventional grindstone to move forward.

After confirming the tilting of the cradle, the workpiece is rotated. In this case, the cradle is biased so that the master cam and the touch roller are always in contact with each other, so as the master cam rotates, the cradle follows the master cam and tilts, and the workpiece follows the shape of the master cam. The cam profile is ground to the desired cam profile.

Further, according to the present invention, there is no need to move the rotary whetstone back and forth each time grinding is performed, and it is sufficient to provide an adjustment mechanism that adjusts the position of the whetstone in accordance with changes in the outer diameter due to dressing of the rotary whetstone. A complicated advancing/retracting mechanism is not required.

(Example) An example of implementing the present invention will be explained with reference to attached drawings. In the drawing, 1 shows a cradle, and the cradle 1 can be tilted forward by a spring 3 about an axis 2 at the root,
A workpiece 4 and a master cam 5 are rotatably provided in this structure, and both 4 and 5 can be driven synchronously by a prime mover, and in front thereof a rotary grindstone 6 facing the workpiece 4 and a touch roller facing the cam 5. 7
This point is not particularly different from the conventional one.

According to the present invention, the rotary grindstone 6 is set in advance at a predetermined depth of cut position and placed on standby, while the cradle 1 is tilted forward while the workpiece 4 and the cam 5 are stopped rotating. Thus, first, the work 4 comes into contact with the grindstone 6 to start grinding, and as the grinding progresses, the cam 5 comes into contact with the roller 7, and the cam 5 and the roller 7 are brought into contact with each other. After confirming the contact, the workpiece 4 and the cam 5 are rotated by a prime mover (not shown). In this way, the workpiece 4 has been ground by the grindstone 6 over the entire circumference of the cam 5.
Then, the cradle 1 is tilted back and returned to its initial position. In the illustrated example, in order to control the tilting of the cradle 1, a hydraulically actuated cylinder 8 is provided on the upper side of the cradle 1 and is opposed to the cradle 1. It is switchably connected to an oil pump 12 via an oil passage 11 for expansion and contraction, and a throttle 13 is interposed in one oil passage 9 so that its contraction speed can be relatively slow. That is, when the cradle 1 is tilted forward by the spring 3, the speed can be made relatively slow. In addition, when starting the grinding of the work 4 mentioned above,
The workpiece 4 is positioned in advance so that it comes into contact with the grindstone 6 at the base circle.

Thus, its operating state is, for example, as shown in the second figure, i.e. the cradle 1 is
tilts forward with the passage of time, and grinding starts at a point b in the middle of that point. Grinding continues until the master cam 5 comes into contact with the touch roller 7 and the forward tilt is stopped, until the base circle of the workpiece 4 reaches a predetermined position. The workpiece 4 is ground to the depth of cut, then the workpiece 4 and the master cam 5 are rotated synchronously, the cradle 1 is tilted as shown in line c following the master cam 5, the workpiece 4 is ground to a predetermined cam profile, and then the workpiece 4 is ground as shown in line d. Return cradle 1 to the cradle 1 and finish the work.

(Effects of the Invention) As described above, according to the present invention, a part of the workpiece can be ground to a predetermined depth of cut when the cradle is tilted to the position where the master cam and the tatsuchi roller contact, and the rotary grindstone is advanced after the cradle is tilted. Grinding can be carried out more efficiently than the conventional method in which grinding is started by grinding, and since there is no need to move the rotary grindstone forward and backward each time grinding, there is no need for a large-scale grindstone advancement mechanism as in the conventional method. Furthermore, it is sufficient to control the rotation of the workpiece after tilting the cradle, which simplifies the control system compared to the conventional method that uses two-step interlock control, resulting in a significant reduction in equipment costs. have

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of one example of the method of the present invention, and FIG. 2 is an explanatory diagram of its operation. 1...Cradle, 4...Work, 5...Master cam, 6...Rotary grindstone, 7...Tatsuchi roller.

Claims (1)

[Claims] 1 A cam grinding method in which a cradle supporting a workpiece is brought into contact with a master cam rotating synchronously with the workpiece and a touch roller, tilting the workpiece to follow the master cam, and grinding the workpiece to a predetermined cam profile with a rotary grindstone. In grinding a part of a workpiece to a predetermined depth of cut with a rotating grindstone while the rotation of the workpiece is stopped, the rotating grindstone is placed in advance at the cutting position of the workpiece defined by the touch roller, and the cradle is placed on the workpiece. While the rotation is stopped, the master cam and the touch roller are tilted until they come into contact with each other, and during this tilting, a part of the workpiece is ground to the predetermined depth of cut using a rotary grindstone, and then the cradle is A cam grinding method characterized in that grinding is performed by rotating a workpiece while the master cam and the touch roller are biased so that they are always in contact with each other.