JPH0253186B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for setting the origin of coordinates on a workpiece when the workpiece is ground by a cylindrical grinder.

<Prior Art> A cylindrical grinder is used when grinding a cylindrical workpiece having a step. NC for cylindrical grinding machine
There are cylindrical grinders and angular slide cylindrical grinders that simultaneously grind the outer peripheral surface and end surface of a workpiece simply by moving a rotating grindstone in one direction.

Figure 1 shows the structure of the angular slide cylindrical grinder. The workpiece 1 is rotatably supported between a headstock 3 and a tailstock 4, and is rotationally driven by a motor (not shown) (attached to the headstock 3), a drive pin (not shown), and the like. The headstock 3 and tailstock 4 are held on a sliding table 6 that is slidably provided on sliding surfaces 7 and 8.
The sliding table 6 includes a servo motor 10 for moving the sliding table 6.
are connected via a feed screw 9. The sliding surfaces 7, 8 and the servo motor 10 are located on the bed 5, and 2 indicates the axis of the workpiece 1. On the other hand, a rotary grindstone (hereinafter simply referred to as a grindstone) 11 is rotated by a motor 13 via a speed reduction mechanism such as a pulley or a belt.
The grindstone stand 12 that holds the grindstone slide base 14
It is slidably supported on sliding surfaces 15 and 16 of.
A servo motor 18 for moving the whetstone head 12 is connected to the whetstone head 12 via a feed screw 17.

Using such a grinding machine, grinding is performed according to control information created based on the finished dimensions of the workpiece 1. A rotation drive command is given to the servo motors 10 and 18 from a control device (not shown) having control information, so that the grindstone 11 engages with the workpiece 1 and the workpiece 1 is ground. In this case, the grindstone head 12
The grindstone slide table 14 is attached to the bed 5 so that the sliding direction of the grindstone is θ ₁ (<90°) with respect to the axis 2, and the workpiece 1 can be moved by simply sliding the grindstone head 12 in one direction. The angular slide cylindrical grinder is characterized by its ability to simultaneously grind the outer peripheral surface and the end surface perpendicular to the outer peripheral surface.

Figure 2 shows the working principle of the angular slide cylindrical grinder. In the figure, 1a is the outer peripheral surface of the workpiece 1,
b is an end surface perpendicular to the outer circumferential surface 1a, and _P1 is the intersection point of the finished surface of the outer circumferential surface 1a and the end surface 1b. In addition, 11a is a grindstone 11 parallel to the outer peripheral surface 1a.
11b is a side surface formed on the grindstone 11 parallel to the end surface 1b, that is, at right angles to the front surface 11a, and _P2 is the intersection of the front surface 11a and the side surface 11b. In addition, 11' is the tip of the grinding wheel 11, and the intersection point
Same position as P ₂ . When the whetstone 11 formed in this way is moved along the straight line connecting the intersection point _P1 and the intersection point _P2 , the front side 11a and the side face 11 of the whetstone 11 are moved.
b will move in parallel with workpiece 1.
The outer circumferential surface 1a and side surface 1b of can be ground simultaneously.

<Problem to be solved by the invention> In a cylindrical grinding machine, when machining a new workpiece for the first time, the coordinate system representing the relative position of the workpiece and the grinding wheel is completely unknown, or the coordinate system is roughly unknown. Even if it is known, it is insufficient for accurate machining, and it is necessary to set accurate coordinates. Further, since the tip of the grindstone 11 is worn out at the same time as grinding, when grinding is performed continuously, the relative position of the workpiece 1 and the tip of the grindstone 11 shifts over time.

Therefore, when grinding the workpiece 1 for the first time or when grinding it continuously, it is necessary to reset the relative positional relationship between the workpiece 1 and the grinding wheel 11 every time one or several times of grinding. Is required.

Therefore, in the past, for example, JP-A-56-52163
As disclosed in the publication, the tip of the grindstone 11 is aligned with the tip of the headstock 3 that supports the workpiece 1, that position is set as the origin, and one coordinate axis is set in the axial direction from the origin. However, the other coordinate axis was set in a direction perpendicular to this.

Such work is generally referred to as origin setting, but an error occurs in the origin setting depending on the accuracy with which the workpiece 1 is attached to the tip position of the headstock 3. Therefore, after the workpiece 1 is held between the headstock 3 and the tailstock 4, it is generally necessary to measure the diameter of the workpiece 11 and correct the origin.

In this way, in the above-mentioned conventional technology, the origin is set on the axis of the workpiece, and therefore setting the origin becomes a complicated task. Also, when aligning the tip of the grinding wheel 11 with the tip of the headstock 3,
If this positioning work were to be done visually, it would be a very nerve-racking and extremely tiring work, and since it was done visually, it would have the disadvantage of being time-consuming, and furthermore, it would require skill. .

In addition, when the diameter of the workpiece 11 to be ground is known and grinding is performed with a constant machining allowance, the origin setting of the workpiece 1 is not necessarily the same as the diameter of the workpiece is known. There is no need to set it on the axis of object 1. Furthermore, even if the diameter of a workpiece is unknown, it may be ground with a constant machining allowance. For example, when the surface of a workpiece is ground extremely thin simply for the purpose of smoothing it. In this case as well, it is not necessarily necessary to set it on the center axis of the workpiece.

The present invention has been made in view of the above-mentioned prior art, and aims to provide an origin setting method that can be easily performed by even an unskilled person in a short time by setting the origin on the outer peripheral surface of a grindstone. This is the purpose.

<Means for Solving the Problems> The configuration of the present invention to achieve the above object is such that when a stepped workpiece is ground by a cylindrical grinder, a grindstone and the workpiece are moved relative to each other so that the grindstone is The contact with either the outer peripheral surface or the end surface of the workpiece is automatically detected by detecting an increase in the electric power of the motor that rotationally drives the grindstone or a fluctuation in the rotation of the workpiece, and the contact line is moved to one side. After setting the reference coordinate axis and then retracting the grindstone from either the outer peripheral surface or the end surface of the workpiece to eliminate the contact state,
The grindstone and the workpiece are relatively moved along the one reference coordinate axis, and the grindstone contacts the other of the outer circumferential surface or end surface of the workpiece by increasing the electric power of the motor that rotationally drives the grindstone, or The present invention is characterized in that rotational fluctuations of the workpiece are automatically detected and the other reference coordinate axis orthogonal to the one reference coordinate axis is set on the contact line.

<Operation> According to the present invention, the grindstone and the workpiece are moved relative to each other, the time when the grindstone contacts the outer peripheral surface or the end surface of the workpiece is automatically detected, and the two contact lines are orthogonally crossed. Since it is set as the reference coordinate axis, even an unskilled person can easily set the origin quickly and safely compared to the conventional case where the coordinate origin was set on the center axis of the workpiece.

In particular, for a workpiece with a known diameter, the workpiece can be ground to a desired diameter simply by grinding the machining allowance from the reference coordinate axis.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

An embodiment of the present invention will be described with reference to FIG. This figure shows the grinding state of a workpiece 1', which is a stepped workpiece 1 with a step added, and 1c.
indicates an outer circumferential surface parallel to the outer circumferential surface 1a, and 1d indicates an end surface perpendicular to the outer circumferential surface 1c. Further, P ₃ is the intersection point of the finished surface of the outer circumferential surface 1c and the end surface 1d.
Other parts are given the same reference numerals as in FIG. 2, and their explanation will be omitted.

Here, a case will be explained in which the angular slide NC cylindrical grinder shown in FIG. 1 is used.

In an angular slide NC cylindrical grinding machine, the outer circumference and end faces at multiple locations are controlled by the servo motors 10 and 18 from the control device using control information created in advance.
A rotation command is given to the grindstone 11 to grind the workpiece 1', but at this time, the movement path of the grindstone 11 with respect to the workpiece 1' is Z, which coincides with the axis 2 of the workpiece 1'. A coordinate axis is provided, and an X coordinate axis is provided in a direction perpendicular to the axis 2, and the grinding wheel 11 is
A common method is to move the tip 11' of the.

By the way, when machining a new workpiece for the first time, either the coordinate system as described above that represents the relative position of the workpiece and the grindstone is completely unknown, or even if the outline of the coordinate system is known, it is difficult to process it accurately. It is insufficient for this purpose, and it is necessary to set accurate coordinates.

As a preliminary step to the origin setting method of the present invention, the origin of the X-axis is placed on the axis 2 of the workpiece 1' in FIG.
The origin of the Z axis is placed on the finished surface of the end face 1b.

Then, set the tip 11' of the grindstone 11 to the initial position.
After moving to P ₂ ′ (X ₀ , Z ₀ ), press a push button (not shown) to instruct the control device to start setting the origin. As a result, the origin setting work starts in the order shown in FIG.

That is, the grindstone head 12 moves at a preset speed (V
mm/min). At this time, the workpiece 1' is rotated at a preset rotation speed. Eventually, the front surface 11a of the grindstone 11 becomes the outer peripheral surface 1 of the workpiece 1'.
Since it makes contact with a, the contact is detected and the movement of the grindstone head 12 is stopped.

In order to detect such contact, a device is provided that detects an increase in the electric power due to the load applied to the servo motor 13, or,
This is done by providing an accelerometer that detects changes in rotational acceleration occurring in the workpiece 1'.

The X coordinate of the contact line between the front surface 11a of the grindstone 11 and the outer peripheral surface 1a of the workpiece 1' when the movement of the grindstone head 12 is stopped is defined as _X1 . That is, in the state of contact, X=X ₁ . Here, the contact line refers to a series of contact points formed on the outer circumferential surface 1a parallel to the axis 2 when the front surface 11a of the grindstone 11 and the outer circumferential surface 1a of the workpiece 1' come into contact.

Next, in order to release the contact state between the front surface 11a of the grindstone 11 and the outer circumferential surface 1a of the workpiece 1', the grindstone head ₁₂ is moved back in the X-axis direction by a preset amount of X2. That is, let X=X ₁ +X ₂ . The reason for releasing these contact states is to stop the output of the accelerometer and the like to facilitate measurement work.

After that, by moving the sliding table 6, the workpiece 1' is moved in the axial direction of the workpiece 1'.
Move it to the right in the figure. However, the initial position of the tip 11' of the grindstone 11 with respect to the workpiece 1' is Z=Z ₀ .

When the side surface 11b of the grindstone 11 eventually comes into contact with the end surface 1b of the workpiece 1, the contact is again detected by the same device as described above, and the movement of the sliding table 6 is stopped.

The Z coordinate of the contact line between the front surface 11b of the grindstone 11 and the outer peripheral surface 1b of the workpiece 1' when the sliding table 6 is stopped is defined as _Z1 . In other words,
In the state of contact, Z=Z ₁ , and the coordinates of the tip 11' of the grindstone 11 when in contact are (X ₁ +X ₂ , Z ₁ ).

Therefore, this coordinate (X ₁ + X ₂ , Z ₁ ) becomes (X ₂ ,
For example, a coordinate conversion command is output to subtract X ₁ and Z ₁ from the X and Z coordinate values, respectively, so that the coordinate system configured in the control device is automatically converted so that

Here, since X ₂ is the amount of retraction for the purpose of releasing the contact state, it may be set to a sufficiently small amount of retraction as long as this purpose can be achieved. In other words, the amount is set to such an extent that the amount of retreat can be approximately zero. In that case, the coordinates of the tip 11' of the grindstone 11 in contact will be (X ₁ , Z ₁ ), and therefore the new coordinates after coordinate transformation will be (O, O).

As a result of this coordinate transformation, the contact line between the front surface 11a of the grinding wheel 11 and the outer peripheral surface 1a of the workpiece 1 becomes the Z axis,
A straight line located on the end surface 1b of the workpiece 1 and perpendicular to the axis 2 and the Z-axis is the X-axis.

As shown in the process of FIG. 4, if the coordinate origin that the operator is trying to determine is the intersection of the outer peripheral surface 1a and end surface 1b of the workpiece 1, then the origin setting is completed. For example, this is the case when grinding is performed with a constant machining allowance from the outer peripheral surface 1a of the workpiece 1.

However, since the diameter of the outer peripheral surface 1a of the workpiece is generally required to be ground to a certain size,
The origin of the coordinates is often required to be on the axis 2. In such a case, the steps up to and including those shown in FIG. 4 are performed continuously.

That is, by moving the grindstone head 12, the tip 11' of the grindstone 11 is moved backward. The coordinates of the tip 11' of the grindstone 11 after retreating are (X ₃ , Z ₂ ) in the newly set coordinate system.

Next, measure the radius of the outer peripheral surface 1a of the workpiece 1,
Let the measured value be _d1 . In addition, the end surface 1 of the workpiece 1
Assume that the machining allowance of b is ΔZ.

Then, the coordinates of the tip 11' of the grinding wheel 11 are (X ₃ +
d ₁ , Z ₂ +ΔZ), for example, coordinate transformation is performed by adding d ₁ and ΔZ to the X-axis coordinate value and the Z-axis coordinate value, respectively.

As a result, the coordinate origins of the X-axis and Z-axis are set at the origin positions shown in FIG. 3, that is, on the axis 2 and on the finished surface of the end surface 1b of the workpiece 1.

Note that here as well, since X ₃ and Z ₂ are the amount of retraction for releasing the contact state, generally X ₃ and Z ₂ are extremely small and can be approximately negligible. For this reason, the grindstone 11 in the above-mentioned contact state
The coordinates of the tip 11' of are (O, O), and the new coordinates after coordinate transformation are (d ₁ , ΔZ).

Further, when the measured value of the outer circumferential surface 1a of the workpiece 1 is not a radius but a diameter, d ₁ /2, which is half of that value, may be used instead of d ₁ .

Incidentally, although an angular slide cylindrical grinder was used in the above embodiment, the present invention is not limited to this. In other words, even if a grinding machine other than this grinding machine is used, for example, a straight cylindrical grinding machine,
Since the outer circumferential surface of the workpiece and its end surface are simultaneously ground, the present invention can be applied. Also,
In this example, since an angular slide cylindrical grinder was used, the grinding wheel was brought into contact with the outer peripheral surface of the workpiece and then brought into contact with the end surface of the workpiece. If it is a board, the opposite may be true. In other words, the grinding wheel may be brought into contact with the outer circumferential surface of the workpiece to set one reference coordinate axis, and then the end face thereof may be contacted to set the other reference coordinate axis, or conversely, One of the reference coordinate axes may be set by contacting the reference coordinate axis first, or the other reference coordinate axis may be set by contacting the outer circumferential surface of the reference coordinate axis later.

<Effects of the Invention> As described above in detail based on the embodiments, according to the present invention, when the grindstone and the workpiece are moved relatively and the grindstone comes into contact with the outer peripheral surface and end surface of the workpiece, is automatically detected and the two contact lines are set as orthogonal reference coordinate axes, making it easier even for unskilled workers compared to the conventional case where the origin was set on the center axis of the workpiece. The origin can be set quickly and safely. In particular, when the diameter of the workpiece to be ground is known, the workpiece can be easily ground to the desired diameter by grinding the machining allowance from the origin on the outer peripheral surface of the workpiece. Furthermore, the same applies even if the diameter of the workpiece is unknown or if only a certain machining allowance needs to be ground.

[Brief explanation of the drawing]

Figures 1 and 2 relate to an angular slide cylindrical grinder, where Figure 1 is a structural diagram, Figure 2 is a diagram of the processing principle, and Figures 3 and 4 show the origin setting method according to the present invention. FIG. 3 is an explanatory diagram, and FIG. 4 is a flowchart. In the drawing, 1' is the workpiece, 1a and 1c are the outer peripheral surfaces,
1b, 1d are end faces, 2 is an axis, 11 is a grindstone, 11
a is the front, and 11b is the side.

Claims (1)

[Claims] 1. When grinding a stepped workpiece with a cylindrical grinder, the grindstone and the workpiece are moved relative to each other, and the time when the grindstone contacts one of the outer peripheral surface or the end surface of the workpiece is defined as The contact line is automatically detected by detecting an increase in the electric power of the rotationally driven motor or a variation in the rotation of the workpiece, and the contact line is set as one of the reference coordinate axes. The grinding wheel and the workpiece are moved relative to each other along the reference coordinate axis of the one, and the grinding wheel is brought into contact with the other of the outer peripheral surface or end surface of the workpiece. This is automatically detected by detecting an increase in the electric power of the motor that rotationally drives the grindstone or a fluctuation in the rotation of the workpiece, and the other reference coordinate axis orthogonal to the one reference coordinate axis is set on the contact line. A method for setting the origin of a cylindrical grinding machine.