JP3170938B2 - Grinding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding machine for grinding a cylindrical portion of a workpiece and a corner adjacent to the cylindrical portion using a grinder which can be relatively moved in a direction parallel to and crossing the axis of the workpiece. It relates to a grinding method for processing.

[0002]

2. Description of the Related Art As a conventional method for grinding a cylindrical workpiece W at high speed, there is a method as shown in FIG. This uses a grindstone G provided with a straight portion Gs parallel to the rotation axis of the workpiece W and a tapered portion Gt inclined with respect to the rotation axis of the workpiece W. First, the grindstone G is positioned at one end of the workpiece W. Then, while rotating the workpiece W and the grindstone G respectively,
The grindstone G moves closer to the workpiece W. That is, the workpiece W is moved in a direction orthogonal to the rotation axis,
Fine grinding and fine grinding are sequentially performed (hereinafter, a method of performing grinding by relatively moving the workpiece W and the grindstone G in a direction orthogonal to the rotation axis of the workpiece W is referred to as plunge grinding). Then, only one end of the workpiece W is processed to a desired finish size. Thereafter, grinding of the entire workpiece W is performed while moving the workpiece W along the rotation axis direction of the workpiece W to the other end of the workpiece W (hereinafter, such grinding is performed in the rotation axis direction of the workpiece W). A method of performing the grinding by relatively moving the workpiece W and the grindstone G along is called traverse grinding). In such a grinding method, rough grinding is performed by the tapered portion Gt of the grindstone G during traverse grinding, and then the straight portion Gs
Thus, the finish grinding can be performed, so that the entire workpiece W can be ground by one traverse grinding.

As shown in FIG. 5, when a cylindrical portion a of a workpiece W is processed by the above-described high-speed grinding, and an arc-shaped corner b and an end face c adjacent to the cylindrical portion a are ground, The grinding was performed in the order of the end face c, the corner b, and the cylindrical part a. Of these, for the grinding of the end face c and the corner b, the cutting amount in the X-axis direction and the feeding amount in the Z-axis direction are controlled by the coordinates of the grinding wheel G (hereinafter referred to as machine coordinates) in the grinding machine.
Regarding the grinding of the cylindrical portion a, in order to emphasize the dimensional accuracy of the cylindrical portion a, the grindstone G is controlled by the coordinates of the workpiece when the workpiece W is actually machined (hereinafter referred to as workpiece coordinates). Was. That is, similarly to the plunge grinding in the above-described high-speed grinding, when the sizing device 16 detects that the diameter of the left end of the cylindrical portion a has reached the target size and outputs a detection signal,
The cutting in the X-axis direction is stopped, and traverse grinding is performed only by feeding in the Z-axis direction to grind the cylindrical portion.

[0004]

In the grinding process, the machine coordinates of the grinding machine and the workpiece coordinates are reduced due to factors such as a decrease in the diameter of the grinding wheel due to wear of the grinding wheel G, eccentricity due to the support of the workpiece, and bending due to rotation of the workpiece W. And a shift occurs. For this reason, the following state occurs when grinding is performed by the above-described conventional technology. That is, as shown in FIG. 6A, the cut in the X-axis direction of the grindstone G is cut by α larger than the actual size, and as a result, the sizing device before the arc shape of the corner b is completely formed. A state where the detection signal of No. 16 is output and the traverse grinding of the cylindrical portion a is started.
Conversely, as shown in FIG. 6B, the X-axis cut on the grinding machine is cut by β smaller than the actual dimension, and as a result, the arc shape of the corner b is completely formed. Still further, a state in which the traverse grinding of the cylindrical portion a is performed and the step portion e is formed after cutting in the X-axis direction by plunge grinding has occurred. Due to the two grinding states described above, there is a problem that the corner b having the target dimensions cannot be formed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a grinding method capable of machining a corner a having an accurate shape according to a target dimension in order to solve the above-mentioned problems.

[0006]

Means for Solving the Problems Plunge grinding is performed while measuring a part of the cylindrical portion with a measuring device, and the diameter of the cylindrical portion is predetermined by the measuring device to be larger than the finishing diameter.
When a signal indicating that it has reached the set value is output, the
Reconfigure the coordinate system in a direction intersecting the workpiece axis of the grinding wheel based on the position of the grinding wheel when the signal is output, its
After that, finish the workpiece based on the reset coordinate system.
Moving the grindstone relative to the workpiece along the
From the corner of the workpiece to the cylindrical part,
The connection is made so that the
Grinding is performed by one continuous grinding feed .

[0007]

First, plunge grinding is performed in a direction intersecting with the workpiece axis while measuring a part of the cylindrical portion of the workpiece with a measuring device. When a signal indicating that the workpiece cylinder has reached the set value is output by the measuring device , the signal is output.
The coordinate system in the direction intersecting with the workpiece axis of the grindstone is reset based on the position of the grindstone at the time of the grinding, and the grindstone and the measuring device are retracted.

Then, the end face, the corner and the cylindrical portion of the workpiece are ground by one continuous grinding by the reset coordinate system.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a grinding machine for grinding a workpiece having an arc-shaped corner using the grinding method of the present invention. Reference numeral 10 denotes a grinding machine main body, and a bed 11 is provided with a table 12 and a grinding wheel stand 13. The table 12 is driven by a table drive servomotor 27 provided on the bed 11 to drive the table 12 by a feed screw mechanism (not shown).
The wheel base 13 can be moved in the axial direction (horizontal direction in the drawing), and the wheel head 13 is driven by a wheel head driving device 26 provided on the bed 11 so that the X axis orthogonal to the Z axis is driven by a feed screw mechanism (not shown). It can be moved in the direction (vertical direction in the drawing).

A headstock 14 and a tailstock 15 are provided on the table 12 and support both ends of the workpiece W at the center. A spindle drive servomotor 28 is fixed to the headstock 14, and the workpiece W is rotated by the drive of the spindle drive servomotor 28. The grindstone table 13 is provided with a grindstone G that is rotated by an unillustrated grindstone rotation motor. The grindstone G is a disc-shaped grindstone core provided with a grindstone layer on the outer periphery thereof. The grindstone layer is formed by bonding CBN abrasive grains with vitrified bonds.
A straight portion Gs parallel to the rotation axis of the workpiece W and a tapered portion Gt inclined with respect to the rotation axis of the workpiece W are provided on the outer periphery of the grindstone G. As shown in FIG. 7, the tapered portion Gt has a length H in the radial direction of the grindstone G of the tapered portion Gt.
Is set to be longer than the distance h from the outer diameter at the start of machining of the workpiece W to the finished workpiece diameter.

Reference numeral 16 denotes a sizing device, which is a table 1
Measuring head 18 on a bracket 17 mounted on
Are supported so as to be able to move forward and backward, and measure the diameter of the cylindrical portion of the workpiece W. A pair of contacts 19 are displaceably supported by the measuring head 18, and a signal corresponding to the amount of displacement of the contacts 19 is output by a displacement detector provided in the measuring head 18 and input to the amplifier 20. . Amplifier 20
Compares an input signal with a preset set value, outputs a sizing signal to a numerical control device 21 described later at a coincidence point,
The feed advance end position of the wheel head 13 is controlled.

The numerical controller 21 is connected to a grindstone drive circuit 36, a table drive circuit 37, and a spindle drive circuit 38.
6. The drive of the table drive servomotor 27 and the spindle drive servomotor 28 is controlled. Next, a description will be given of a grinding process for machining an arc-shaped corner using the grinding method according to the present invention with reference to FIGS. FIG. 2 is a diagram showing a first grinding process in which the cylindrical portion a of the workpiece W is plunge-ground while measuring the size, and FIG. 3 is a second grinding process in which the workpiece is actually ground to a target size.
It is the figure which showed the grinding process.

First, as shown in FIG. 2, the measurement position of the sizing device 16 in the cylindrical portion a of the workpiece W is subjected to first grinding by plunge grinding. The sizing device 16 performs in-process measurement, which always performs measurement during plunge processing,
When the grinding is performed to a set value to be described later, a fixed size signal is output to stop the cutting of the grindstone G. Here, the set value is set to a value that is larger by a small amount Δd than the actual finished dimension D (the two-dot chain line in the drawing).

When the sizing signal is output and the cutting of the grindstone G is stopped, the coordinate system in the X-axis direction of the grindstone G at this position is reset, and the grindstone G is retracted. Then, the machine coordinate system of the grinding wheel G and the workpiece coordinate system, which is the coordinate system of the shape of the workpiece, coincide with each other. Therefore, as shown in FIG. P2 is plunge ground,
A second grinding process is performed in which the section P2-P3 of the corner b is circularly ground and the traverse grinding of the section P3 and subsequent sections of the cylindrical portion a is performed.

Next, FIG. 4 will be described in detail with reference to a flowchart showing the flow of the grinding process of the present embodiment. In step 100, the numerical controller 21
The value (set value) of the diameter of the workpiece W when the fixed size signal is output is set. This value is set to a value that is large by a small amount Δd to the finishing dimension D of the cylindrical portion a of the workpiece W so as not to affect the processed surface when the main grinding is performed.

In step 101, the sizing device 16 is advanced, and the grindstone G is cut while the in-process measurement is performed by the sizing device 16 until the diameter of the cylindrical portion a of the workpiece W becomes D + Δd. The cut of the grindstone G is actually given the value of D + Δd−Δv, in which the overcount value Δv is subtracted in consideration of the deviation between the machine coordinates and the workpiece coordinates, and the grindstone G always reaches the set value. It has become.

In step 102, the coordinate system of the grinding wheel G is reset. The resetting of the coordinate system as used herein means that the deviation between the machine coordinates and the workpiece coordinates is obtained and the machine coordinates are corrected, and the value of a counter (not shown) that counts the current position of the grinding wheel head 13 is used. And the value of the sizing device 16 (actually, the machine coordinates are newly set by the G code (G92) of the NC program, and the machine coordinates and the workpiece coordinates are matched).

In step 103, the grinding wheel G (specifically, the grinding wheel base 13) is retracted, and in step 104, the sizing device 16 (specifically, the measuring head 18) is retracted. In step 105, as shown in FIG. 3, a second grinding process for actually grinding the workpiece W to a target size is performed. At 105a, the end face c is plunge-ground, and then at 105b, the corner b is arc-ground. Finally, the cylindrical portion a is traversed to finish the grinding. In this case, since the machine coordinates are reset in step 102, the position of the grindstone G in the machine coordinates matches the dimension of the workpiece, and the arc grinding of the corner b is started from the grinding end point P2 of the end face c. , The end point P3 of the corner b grinding
Then, traverse grinding of the cylindrical portion a is started, and the corner b having the target size is formed.

As described above, when machining the end face c, the corner b, and the cylindrical part a of the workpiece W, after grinding the end face c and the corner b in the conventional manner, using the sizing device 16, Instead of starting the grinding of the part a, first, the measuring position of the cylindrical part a by the sizing device 16 is ground by an appropriate amount, the coordinates of the grinding wheel table are corrected, and then the end face c, the corner b, and the cylindrical part a Since the machining is performed, there is an effect that the accuracy of the cylindrical portion a is secured and the corner portion b can be ground to the target size.

In this embodiment, after the machine coordinates of the grinding wheel head are reset, the grinding process is performed in the order of the end face c, the corner b, and the cylindrical part a. However, the cylindrical part a, the corner b The same effect can be obtained by processing in the order of the end face c. In the present embodiment, the formation of the arc-shaped corner has been described, but the tapered corner can be ground in the same manner.

[0021]

As described above, in machining a cylindrical portion and a corner of a workpiece according to the present invention, grinding of the cylindrical portion is started using a measuring device after grinding the corner as in the conventional method. Instead, first grind the measuring position of the cylindrical part by the measuring device by an appropriate amount, reset the coordinate system in the direction intersecting the grinding wheel axis, correct it correctly, and then grind the cylindrical part and corner part Thus, there is an effect that the accuracy of the cylindrical portion is ensured, and the corners can be ground to the target dimensions.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a grinding machine showing an embodiment of the present invention.

FIG. 2 is a view showing a first grinding process.

FIG. 3 is a view showing a second grinding process.

FIG. 4 is a flowchart showing a grinding process.

FIG. 5 is a view showing a conventional grinding process.

FIG. 6 is a diagram showing a conventional grinding result.

FIG. 7 is a diagram illustrating a conventional grinding process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Grinding machine 12 Table 13 Tailstock 16 Sizing device 20 Amplifier 21 Numerical control device G Grinding wheel L Workpiece axis W Workpiece

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-149993 (JP, A) JP-A-56-3168 (JP, A) JP-A-58-59759 (JP, A) 25030 (JP, B1) JP 50-27636 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B24B 49/00-49/18 B23Q 15/00 309 B24B 5/14

Claims (1)

(57) [Claims] A measuring device for measuring a diameter of a cylindrical portion of a workpiece, a straight portion parallel to a workpiece axis, and a workpiece shaft;
A grindstone having a tapered portion inclined with respect to a line, the grindstone can be relatively moved in a direction parallel to the workpiece axis and in a direction intersecting the same, the cylindrical portion of the workpiece and the In a grinding method for grinding a corner portion adjacent to a cylindrical portion, plunge grinding is performed while measuring a part of the cylindrical portion with the measuring device, and the diameter of the cylindrical portion is larger than a finished diameter by the measuring device. When a signal indicating that the set value has been reached is output, the signal is output.
Reconfigure the coordinate system in a direction intersecting the workpiece axis of the grinding wheel based on the position of the grinding wheel when it is, the
After that, finishing the workpiece based on the reset coordinate system
Moving the whetstone relative to the workpiece along the shape,
The taper of the grinding stone from the corner toward the cylindrical portion
Continuous so that the part precedes the processing direction of the cylindrical part
A grinding method characterized in that grinding is performed by a single grinding feed .