JPS5856758A - Automatic centering device for larger works - Google Patents

Abstract

PURPOSE:To have an automatic centering on the basis of the amount of deviation by catching the reference line drawn on a three-dimensionally curving surface in the form of a picture projected on an image sensing device, converting into a line on a two-dimensional plane, and by determining thereby the amount of deviation with respect to the machine tool at the reference line. CONSTITUTION:In a position where a reference line marked on the surface of a work 2 is visible, a TV camera 8 is fixed out of the table 1, which is to bear the work 2 and rotate. An image signal caught by the TV camera is transmitted to an image processing device 9, which is to find out the reference line 3 from difference in brightness between the line 3 and its surroundings. The change of the intersecting point of the reference line with the normal l in the view field 11 and that of distance d from one end of the view field 11 are determined, and jacks 4-4'' are shifted according to their respective differences from the mean value using the d value and the mean value of maxium and minimum to have centering alignment of the table 1 with reference line 3. Thereby an accurate centering alignment can be made even though the work has uneven surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic setup device, and more particularly to an automatic centering device equipped with an image detection device and an image processing device suitable for setting up a workpiece with an irregular surface in a machine tool.

Conventional setup devices include methods that measure the deviation between the workpiece and the reference surface of the machine tool using a contact or non-contact displacement meter on the surface of the machined surface, and then move the workpiece. Measure the narrow surface shape of a regular workpiece with a three-dimensional measuring head,
There are methods of calculating the machining reference plane by calculation, but the former uses a plane as the reference, and has the disadvantage that the plane that will serve as the reference must be machined in advance. The latter requires inputting the shape and dimensions of the workpiece in advance because the reference plane is calculated by calculation.
There is a complexity.

The purpose of the present invention is to easily match the workpiece to the machine tool standard by detecting a reference line pre-marked on the workpiece using an image detection device and minimizing the deviation between the workpiece and the machine tool standard. To provide automatic centering equipment.

Figure 3 shows an example of a workpiece. As shown in this figure, the surfaces of unprocessed parts often have irregular shapes. The present invention captures such a reference line on a three-dimensional curved surface as an image of an image detection device, converts it into a line on a two-dimensional plane, and calculates the amount of deviation of the reference line with respect to the machine tool. The setup is performed by issuing a move command to the jack that moves the workpiece.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. This implementation yIJ is a jack 4 that moves the workpiece 2.
and 5, a jack control device 10 that controls the amount of movement of the jacks 4 and 5, a calculation device 6 that calculates the distance that the jacks 4 and 5 should move, and a reference line 3 attached to the workpiece 2.
ft Consists of a television camera 8 as an image detection device for photographing, an image processing device 9 for processing the photographed image and detecting the position of a reference line in the image, and a rotation angle detector 7 for detecting all rotation angles of the table. has been done.

Hereinafter, as an example, a method of aligning the center Ow of the reference line 3 previously attached to the workpiece 2 with the rotation center 0 of the table will be explained.

Generally, large-sized processed parts are often welded structures or cast products. Therefore, the surface shape of the processed part has irregular irregularities as shown in FIG. In order to process the workpiece to the desired dimensions, the workpiece 9J must be placed in a position that will accommodate all the objects that are to be cut on the table 1. In the first example, we are trying to use the sword to the diameter of the reference line 3, or the diameter of a circle that is concentric with the reference line 3. For this purpose, the center of the reference a3 and the rotation center of the table 10 must be aligned.

In Fig. 1, when the table 1 is rotated and the reference line 3 is viewed from directly above from a stationary place outside the table 1, the center Qw of the reference line 3 and the rotation center O of the table 1 are aligned. If so, the reference line 31 does not change Vi in the normal direction, and conversely, if the above Ow and the rotation center 0 do not coincide, the reference line 3 changes in the normal direction. In this embodiment, the television camera 8 is installed and fixed outside the table at an appropriate position such that the reference line 3 enters the Hagino field, and the table is rotated.

The television camera obtains an image of the area surrounded by the field of view 11. When the distance d from the intersection of the normal t and the reference line 3 in the visual field ll and one end of the visual field 11 becomes constant, the center Ow of the reference line 3 and the rotation center O of the table 1 coincide. Become. If the above Qw and 0 do not match, the relationship between the angle θ formed by the xi of the coordinate X-Y that rotates with the table and the stationary coordinate X-axis, and the above distance d is shown in Figure 4. It becomes a periodic function like this. In a false example, an image signal captured by a television camera 8 is transmitted to an image processing device 9. In the image processing device 9, based on the brightness difference between the reference line 3 and the same song,
The reference 73ft is found, the distance dl is determined, and the distance dl is transmitted to the arithmetic unit 6. The calculation device 6 receives the distance d and the angle θ between the X axis of the table 1 and the stationary coordinate X axis when the television camera 8 captures the image from the rotation angle detector 7,
Table rotations are stored in orderly correspondence. Thereafter, the arithmetic unit 6 calculates d in FIG. 4 from the stored data.
Find the maximum and minimum values of and find their average line,
The average 4L and each jack 4.4'.

The difference between each of the above distances d when 4//, 4/l/ passes through t and the distance 1 of the average line 'I * d2
e d3sd4 is determined and transmitted to the jack control device 10 in the above-mentioned form dr, d2, ds, d4't-. Nyatsuki system @ Nao is Tani Jyatsuki Tani dl +
It is controlled to move by d2 + d3 + d4.

As a result of the above, the center OW of the reference line 3 attached to the workpiece 2
approaches the rotation center 0 of the table 1. Top = i4 work τkuri〃・Esutoyoshi, above center Owi'[, center of rotation O
The centering is completed when the deviation is below the allowable value.

In the same, we have described the centering of the μ vertical drilling machine in this example, but the centering is OTI based on the same principle in the horizontal boring machine that moves in a straight direction and performs cutting, and in the Plei/Guand milling machine. ]l: For vertical and vertical machining lathes, OT is also effective for centering in a plane perpendicular to the table rotation axis.

In this implementation, we use two television cameras mounted vertically and horizontally in Figure 2, but the reflection g! , i45°l'l Rather than attaching or removing a single TV camera, it can be used both vertically and horizontally, without changing the direction of mounting the TV.
and 3' all can be captured.

According to the present invention, the reference line drawn on the workpiece is horizontally drawn out by the one-plane image detection device, and the workpiece gJ is
In order to match the standard of the machine tool, even if the surface of the workpiece is irregular, it is possible to carry out the setup quickly and accurately.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram illustrating the method for centering a one-dog machine according to the present invention.
Is the ll side view and Figure 3 the invention? FIG. 4, which is a perspective view showing the temperature of usable machining powder, is a graph showing the difference in change between the table rotation angle and the reference line obtained from the image in one embodiment of the present invention.

Claims (1)

[Claims] 1. In a machine tool equipped with a jack that is fixed on a table on which a workpiece is installed and that can drive the workpiece in response to a command, an image detection device that detects a reference previously set on the workpiece; an image processing device that detects the position A of the reference line in the image based on image information from the detection device; a movement amount detection device that detects the amount of relative movement between the image detection device and the workpiece; and from the image processing device. a calculation device that calculates a deviation amount between the machine tool and the workpiece from the position of the reference line and the relative movement amount between the workpiece and the image detection device from the movement amount detection device;
An automatic centering device for a large workpiece, comprising a control device for controlling the amount of movement of the drivable jack.