JPH04353760A - Flaw detector - Google Patents

Abstract

PURPOSE:To obtain an apparatus which can detect a flaw of a workpiece having a complicated shape by a simple structure and with stable precision. CONSTITUTION:A mechanism X for rotating a workpiece W, a mechanism Z for moving a probe 40 having a detecting head (sensor) 42 in the direction parallel to the line of the axis of rotation of the workpiece, and mechanisms 36 and 38 for pressing a head 26 against the workpiece W, are provided. The rotation of the workpiece W and the movement of the head 26 are combined and the head 26 scans the workpiece W spirally. On the occasion, a distance between the detecting head (sensor) 42 and the workpiece W is kept constant and thus execution of stable detection is enabled.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting flaws in a workpiece, such as cracks and cracks in a cast material.

0002

[Prior Art] Conventionally, in order to detect scratches on a workpiece,
The method used is to scan the workpiece surface with a detection head. FIG. 6 shows a conventional scanning method. In FIG. 6(A), a ring-shaped detection head H is moved within the workpiece W in order to detect flaws on the inner surface of the workpiece W. In FIG. 6(C), in order to detect flaws on the outer peripheral surface of the rod-shaped workpiece W, the workpiece W is moved relative to the ring-shaped detection head H. Figure 6
In (B), in order to detect the flaw A on the workpiece W, the detection head H is scanned while being moved in parallel.

0003

[Problems to be Solved by the Invention] However, according to the above scanning method, as partially illustrated in FIG. is difficult to scan. For example, Figure 6(A)
Or, according to the method (C), it is not possible to maintain the gap G between the detection head H and the workpiece W appropriately for a workpiece whose circumferential radius changes variously, and the detection accuracy cannot be kept constant. Difficult to maintain. Further, according to the method shown in FIG. 6(B), a mechanism for moving the detection head H three-dimensionally is required, resulting in a very large-scale apparatus. Therefore, the present invention proposes a flaw detection device that can detect flaws with uniform detection accuracy and has a simplified mechanism for scanning the work surface with a detection head.

0004

[Means for Solving the Problems] Therefore, the present invention is a device that detects flaws on a workpiece by scanning the surface of the workpiece with a detection head. a contactor having the detection head attached at a position offset by a predetermined distance; a support member having a guide surface for guiding the contactor in a direction toward and away from the work surface; and a support member provided between the contactor and the support member. We have created a flaw detection device that has a spring that presses the contactor against the workpiece surface, a means for rotating the workpiece around one axis, and a head moving mechanism that moves the support member in a direction parallel to the rotational axis of the workpiece. .

[0005]

According to the above structure, the workpiece is rotated, and the detection head attached to the contactor is moved in a direction parallel to the rotational axis of the workpiece by the head moving mechanism. Since this device only requires a rotation mechanism and a movement mechanism in one direction, the structure for scanning is greatly simplified. When the workpiece is rotated and the support member is moved in a direction parallel to the rotational axis of the workpiece, the movements of both are combined and the surface of the workpiece is scanned by the detection head. Here, the detection head is pressed against the side of the workpiece by a spring and the distance between the detection part of the detection head and the workpiece is maintained at a predetermined value. According to the present invention, the surface of the workpiece can be inspected with uniform precision using a simple structure. can be inspected.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A shows a front view of a flaw detection device embodying the present invention, and FIG. 1B shows a side view. This flaw detection device includes a workpiece lower support mechanism Y that rotatably supports the workpiece from below, a workpiece upper support mechanism X that supports and rotates the workpiece above, and a head movement mechanism that moves the detection head 26 within a vertical plane. It is composed of Z.

First, the workpiece upper support mechanism X will be explained. For this mechanism, a cylinder 2 is fixed to a frame 4 facing vertically downward. Further, two guide rails 4b are fixed to the front plate 4a of the frame 4 in parallel in the vertical direction. A subframe 6 for the upper support mechanism X is vertically movable with respect to the guide rail 4b via a total of four guides 6b and 6c. A bracket 6a is fixed to the rear of the subframe 6, and the bracket 6a is fixed to the piston 2a of the cylinder 2. With the above configuration, the subframe 6 can be moved up and down by the cylinder 2. Motor 8 is attached to subframe 6
is fixed. A rotating shaft of the motor 8 passes through a bearing 8a and is fixed to an upper chuck 10. That is, the upper chuck 10 is rotatable by the motor 8.

Next, the workpiece lower support mechanism Y will be explained. For this mechanism, a cylinder 12 is fixed vertically downward to the frame 4c. The piston 12a of the cylinder 12 is connected to a subframe 14 for the lower support mechanism Y. A bracket 14 is attached to the subframe 14.
A bearing 16 is fixed via a, and this bearing 1
6 rotatably supports a lower chuck 18. The rotation centers of the upper chuck 10 and the lower chuck 18 are placed on the same vertical line C.

Next, the head moving mechanism Z will be explained. For this mechanism, a motor 20 is fixed to the frame 4d so as to face vertically downward. Also, the support plate 4e of the frame 4
Two guide rails 4f are fixed vertically downward and parallel to each other. The head frame 22c is vertically movable with respect to the guide rail 4f via a total of four guides 22a and 22b. A bracket (not shown) is fixed behind the frame 22c, and this bracket is fixed to a feed screw connected to the motor 20. This mechanism allows the head frame 22c to be moved up and down by the motor 20.

A head movement device 24 is fixed to the head frame 22c, and the head 26 can be moved back and forth in the left-right direction in FIG. 1(B). That is, the head 26 is movable vertically by the motor 20 and horizontally by the advance/retreat device 24, and is movable within a vertical plane including the rotational center axis C of the workpiece (within the plane of the paper in FIG. 1B). It becomes.

FIGS. 2 and 3 show details of the head 26. 30 shows a bracket that is moved forward and backward by the head movement device 24, and a guide rail 32 is fixed to this bracket. A head frame (contact element) 40 is slidable on this guide rail 32 via a guide 34. A guide bar 36 is fixed to the head frame 40. The guide bar 36 passes through a hole in the vertical side 30a of the bracket 30 and extends to the right. A spring 38 is inserted in a compressed state between the vertical side 30a and the head frame 40, and normally urges the head frame 40 to the left in the figure with respect to the bracket 30. In this embodiment, the support means is constituted by the bracket 30 and the like, and the guide surface is formed by the guide hole of the rail 32 and the guide bar 36.

As best shown in FIG. 3, the head frame 40 is branched in the horizontal direction, and a roller 44 is provided at each end thereof so as to be rotatable about a vertical axis. A detection head, in this case a sensor (detection head) 42 that detects the eddy current flowing in the workpiece W to detect the presence or absence of scratches on the workpiece W, is fixed at the base of the two forks separated by a predetermined distance G from the roller 44. There is.

When the head 26 is controlled by the motor 20 and the head advancing/retracting device 24 in a positional relationship such that the tip of the head slightly enters the workpiece W, the spring 38 contracts and the roller 4
4 comes into contact with the workpiece W, and the distance between the workpiece W and the sensor 42 is kept constant. In addition, since the sensor 42 is attached to the base of the bifurcated part and supported on both sides, the work W
Even if the surface is slightly uneven, it is stably supported and there is no risk of damage.

Next, a description will be given of how this detection device detects flaws on the workpiece W. First, the height of the lower chuck 18 is adjusted by the cylinder 12. Next, the workpiece W is placed on the lower chuck 18. In this state, extend cylinder 2,
The upper chuck 10 is lowered to chuck the upper part of the workpiece W. Thereafter, the motor 20 is adjusted so that the height of the head 26 matches the height of the upper end of the workpiece W. Then, the head advancing/retracting device 24 is extended and the head 26 is brought into contact with the circumferential surface of the workpiece W, so that the spring 38 is in a compressed state. This completes the measurement preparation.

After the preparations are completed, the motor 8 is rotated and at the same time the motor 20 is lowered at a predetermined speed. Then, the head 26 spirally scans around the workpiece W with the roller 44 in contact with the workpiece W. At this time, the sensor 42 is always separated from the workpiece W by the gap amount G, allowing accurate measurement. Further, the sensor 42 will not be damaged due to contact with the workpiece W. Here, if the radius of the workpiece W does not change much in the axial direction, it can be followed only by the deformation of the spring 38, and there is no need to adjust the head advance/retreat device 24. However, if the radius changes significantly and cannot be followed by the deformation of the spring 38 alone, the head advancing/retracting device 24 may be moved back and forth appropriately as the axial position changes.

According to this device, irregularities on the circumferential surface of the workpiece W, which are difficult to detect using conventional scanning methods, can be detected extremely quickly and with constant accuracy. In this embodiment, the head frame 40 can be floated in the direction approaching the workpiece, but by making the tip of the head frame 40 rotatable around a point P shown in FIG. It may also be possible to allow floating in this direction.

[0017]

[Effects of the Invention] According to the present invention, it is possible to scan a workpiece having a complicated shape while keeping the flaw detection head at a constant distance from the surface, and the structure for this purpose is extremely simplified. . Furthermore, since the workpiece is inspected by rotating the workpiece and moving the contactor, the entire side surface of the cylindrical workpiece can be thoroughly inspected. Therefore, it is possible to inspect the workpiece for flaws with stable accuracy using an inexpensive device, making it a highly useful invention.

[Brief explanation of drawings]

FIG. 1 is a front view and a side view of a flaw detection device according to an embodiment.

FIG. 2 is an enlarged side view of the head.

FIG. 3 is an enlarged plan view of the head.

FIG. 4 is a diagram showing another application example of the present invention.

FIG. 5 is a diagram showing another application example of the present invention.

FIG. 6 is a diagram showing a conventional scanning method.

[Explanation of symbols]

26: Head 20, 24: Head moving means 8: Work rotation means 38: Detection head pressing spring 40: Head frame (contact) 42: Detection head (sensor)

Claims (1)

[Claims] Claim 1: A device that detects flaws on a workpiece by scanning the surface of the workpiece with a detection head, and is located between a bifurcated contact portion with a roller attached to the tip and at a position offset from the roller by a predetermined distance. A contact to which the detection head is attached, a support member having a guide surface that guides the contact in a direction toward and away from the work surface, and a support member provided between the contact and the support member to guide the contact to the work surface. A flaw detection device having a pressing spring, means for rotating the work around one axis, and a head moving mechanism for moving the support member in a direction parallel to the rotation axis of the work.