JPS628123B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measuring device for measuring the position of a hole edge of a through hole perpendicular to an axis of an object to be measured with respect to an axial reference plane.

An object of the present invention is to accurately measure the position of the hole edge while continuously rotating the object to be measured without indexing it to a fixed angular position, and to shorten the measurement time.

Conventionally, there has been no device that automatically measures the position of the hole edge of a through hole perpendicular to the axis. Therefore, the object to be measured is rotatably supported at both centers, and the hole edge of the through hole is rotated by hand while observing the hole edge of the through hole. However, such measurements were not only inefficient, but also hindered production management automation.

A contact method has been considered as an attempt to automate such measurements, but in order to bring the contact of the displacement detector into contact with the inside of the through hole, it is necessary to accurately index the object to be measured at a fixed angle position. If there is even a slight indexing error, accurate measurements cannot be made. Moreover, if the diameter of the hole is small, it is difficult to insert the contact, which not only promotes measurement errors, but also makes it extremely difficult to bring the contact into contact with the edge of the hole. It has no choice but to make contact with the inner world. Therefore, if the roundness and surface roughness of the inner surface of the through hole are poor, accurate measurement of the hole edge cannot be expected due to the influence of these factors. Moreover, it took a long time to accurately locate the through hole at a certain angular position, which resulted in a long measurement time, and it was found that such a contact method was not very practical.

After undergoing such trials, the present invention has made it possible to measure hole edge positions without contact and without angular positioning of the object to be measured.

Embodiments of the present invention will be described below based on the drawings.

An example of the object to be measured W is shown in Fig. 1. This is a type of valve, and a through hole h is bored perpendicular to the axis, and the through hole is located closer to the reference plane with respect to the center hole c, which serves as the axial reference plane. The dimension up to hole edge e shall be measured. FIG. 2 is a diagram showing the measurement principle. One end of the object W on the reference surface side is supported by a fixed reference sensor 1, and the other end is supported by a movable center 2 that can move forward and backward and is rotationally driven. ing. A projector 3 that emits a parallel beam of light is arranged on one side of the axis of the object to be measured W, and a projector 3 that emits a parallel beam of light is placed on the other side, and a beam that passes through the through hole h when the center line of the through hole h becomes parallel to the beam is placed on the other side. A video camera 4 is arranged to form a Hall Edge image from the projector side onto an image sensor 5. The image sensor 5 has a large number of photodiodes installed at minute intervals, and a Hall Edge image formed on the image sensor 5
Each photodiode is sensitive to e' (bright and dark image) and outputs an electrical signal. As shown in FIG. 3, this image sensor 5 is arranged in a direction passing through the center of the Hall edge image e' and parallel to the axis of the object to be measured W, so if the signal output of each photodiode is sequentially scanned, the image sensor 5 shown in FIG. Obtained as a pulse signal shown in b,
The number of pulse signals exceeding the reference level _V1 is counted as the number of incident light bits.

The light incident area of the hole edge that is imaged on the image sensor 5 increases and decreases as the object to be measured rotates.
When the optical axis and the center line of the through hole become parallel, the light incident area of the hole edge becomes maximum. Therefore, the image sensor output signal is scanned and the number of incident light bits is counted.
The maximum value of the count value per scan obtained during half a rotation is taken as hole edge position detection data. This measurement data is compared with a reference value to determine the amount of positional deviation of the hole edge. The optical axis of the video camera 4 is tilted with respect to the orthogonal axis S, which is perpendicular to the axis, by an angle θ that allows the hole edge on the projector side to be seen through even if the perpendicularity of the through hole h is twisted.

The structure of a hole edge position measuring device to which this measurement principle is applied will be explained with reference to FIGS. 4 and 5.
20 is a base; 21, 22, and 23 are intermediate bases placed on the base 20; and on the intermediate base 21 is a center support stand 25 on which a reference center 24 is mounted.
and a headstock 28 bearing a spindle 27 on which a movable center 26 is mounted and capable of rotation and axial movement;
A spindle drive motor 29 is mounted. A spindle advance/retreat drive device is built in the headstock 28. On the intermediate base 22, the object to be measured W
A projector 30 is placed on one side of the intermediate base 23, and a video camera 31 is placed on the other side of the axis. 32 is a hopper for storing the object W to be measured;
3 is a parts feeder that aligns the posture of the object W to be measured and sends it out from the hopper 32; 34 is a conveyance chute; 3
Reference numeral 5 denotes an escape device installed at the tip of the transport chute 34 to separate and deliver the objects to be measured W one by one;
Reference numeral 36 denotes a rotatable carry-in arm that carries the workpiece W delivered from the escape device 35 to both center support positions, 37 a swing drive device that turns the carry-in arm 36, 38 a carry-out chute, and 39 a hole edge position A selection gate that is selectively opened and closed based on measurement data divides the holes into multiple ranks according to the amount of positional deviation of the hole edge. Reference numeral 40 denotes a storage box that stores the ranked objects W to be measured for each rank. 41 is a control device that processes the output signal from the video camera 31 and determines the hole edge position.

The configuration of this control device 41 will be explained with reference to FIG.

50 is a clock generation circuit, 51 is a scanning circuit,
A clock pulse generated from the clock generation circuit 50 outputs a scanning signal for detecting each bit of light incident on the image sensor 5. Reference numeral 52 denotes an amplifier for video pulses output from the image sensor 5, and 53 a counter, which counts video pulses output in correspondence with incident light bits and detects the number of incident light bits. This counter 53 is reset each time by a start pulse from the scanning circuit 51, and counts the incident light bit video pulses given thereafter, so that when scanning is completed, the value becomes the number of incident light bits for each scan. 54 and 57 are interfaces, 55 is a microcomputer, 56 is a memory, and 58 is a measured value display device. Each time the scan circuit 51 receives each scan end signal, the count value of the number of incident light bits of the counter 53 is read into the computer 55. The read count values are processed within the computer 55 according to the flowchart shown in FIG. Steps (i), (ii)
The count read in step (iii) is compared with the stored value stored at a specific address in the memory 56, and the larger value is stored at the specific address. If this is repeated until a half-rotation signal of the object W to be measured is obtained, the maximum value of the count value will be detected. step
When the half-rotation signal is detected in (iv) and (v), the stored value at the specific address is stored in the memory as the maximum value.
These steps are executed repeatedly until the maximum value is 4.
Once the data have been stored, the process proceeds from step (vi) to step (vii), where the average value of the maximum values is calculated, the average value is compared with the reference value, and the data is ranked into a plurality of ranks according to the deviation.
The ranking signal is output to the sorting gate 39, controls opening and closing of the gate, and ranks the objects to be measured to be sent to the carry-out chute 38 upon completion of the inspection.

Next, a measurement operation based on this configuration will be explained.

The object to be measured W in the hopper 32 is the parts feeder 3
3, the materials are aligned in attitude and supplied to the transport chute 34, separated one by one by the escape device 35, and delivered to the carry-in arm 36. The carry-in arm 36 rotates and the spindle 27 reaches the state shown by the two-dot chain line in FIG. 4. The spindle 27 moves forward and supports the object W at both ends with the reference center 24 and the movable center 26. The carry-in arm 36 rotates back and waits. When the spindle 27 is rotated, the object W to be measured is rotated by the frictional force with the contact surface of the movable center 27. In this case, since the radial position of the contact point of the movable center 26 is larger than the contact point of the reference center 24 with respect to the center axis, the friction torque is larger on the movable center side. Therefore, slippage occurs on the contact surface on the reference center side, causing the object to be measured W
is rotated.

Light projected from the light projector 30 as the object to be measured rotates is received by the video camera 31 through the through hole h every half rotation, and forms a Hall-edge image on the image sensor 5. The output signal of each photodiode incorporated in the image sensor is scanned at high speed, the number of incident light bits corresponding to the incident area is counted by a counter, the counted value is read into the computer 55, and the data is processed as described above and ranked. Issue a separation signal. The ranked selection signal operates the selection gate 39 to open or close a predetermined gate. When the measurement of the hole edge position is completed, the spindle 27 is retracted, and the objects to be measured W are dropped into the carry-out chute 38, passed through the selection gate 39, sorted into the same rank, and stored in the storage box 40. spindle 27
When the carry-in arm 36 moves backward, the carry-in operation of the carry-in arm 36 is started again, and the hole edge position of the next object W to be measured is measured. In this way, hole edge positions are continuously measured and sorted in a fully automatic manner.

According to the above embodiment, as a means for scanning the image sensor and detecting the number of incident light bits, the incident light bit video pulses output from the video pulse amplifier 52 are counted by the counter 53. Since the total number of bits of 5 is constant,
The number of light incident bits can also be determined by detecting the number of light incident bits and calculating (total number of bits) - (light non incident bit number).

Detection of the number of non-light-incident bits is carried out by a gate controlled by the reset side output of the flip-flop 60, which is reset by the scan start signal and set by the first light-incident bit video pulse, as shown in FIG. The clock pulses supplied from the clock pulse generation circuit 50 via the counter 5
It is sufficient to count at 3a. Counter 5 in this case
Reference numeral 3a denotes an addition counter which is reset by a scan start signal. Also this counter 5
By using 3a as a subtraction counter, the number of incident light bits can be detected by presetting an initial value corresponding to the total number of bits of the image sensor using the scanning start signal and subtracting it with the clock pulse given from the gate 61. Any configuration is effective as a number detection means.

According to the present invention, the projector is placed on one side of the object to be measured, and the video camera that images the hole edge of the projector on the image sensor through a through hole is arranged on the other side. Since the number of incident light bits is detected by scanning at high speed, the position of the hole edge on the reference surface side can be accurately measured while the object to be measured is continuously rotated. In addition, since the light transmitted through the through hole is received and a hole edge image is formed on the image sensor,
The brightness contrast of the hole edge image can be strengthened, and the signal level change can be large at the boundary between the light-incident bit and the non-light-incident bit, so the light-incident bit position can be clearly distinguished, preventing measurement errors from intervening, and improving accuracy. It has the effect of increasing

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 shows an example of the shape of an object to be measured, FIG. 2 shows the principle of Hall Edge measurement, and FIG. 3 shows the relationship between the Hall Edge image and the image sensor. , Figure 4 is a front view of the entire measuring device, Figure 5 is its left side view, Figure 6 is a block diagram of the control device, Figure 7 is a flowchart of measurement data processing, and Figure 8 is the number of incident light bits. It is a figure which shows another Example of a detection means. 3, 30... Floodlight, 4, 31... Video camera, 5... Image sensor, 24... Reference center, 26... Movable center, 28... Headstock, 51
... Scanning circuit, 53 ... Counter, 55 ... Microcomputer, 56 ... Memory.

Claims (1)

[Claims] 1 A measuring device that measures the position of a hole edge of a through hole perpendicular to an axis with respect to an axial reference plane of a measured object while rotating, the reference plane of the measured object being positioned at a fixed position and the axis line A device for supporting an object to be measured rotatably supported at the center, a drive device for rotating the object to be measured supported by the device supporting the object to be measured, and a drive device for rotating the object to be measured supported by the object supporting device; A video camera that forms a bright and dark image of the hole edge on an image sensor using a projector arranged to project light and a lens arranged on the other side across the axis and focused on the hole edge on the projector side through the through hole. and an incident light bit number detection means for detecting the number of incident light bits by repeatedly scanning the image sensor at high speed; 1. A hole edge position measuring device comprising: position determination means for comparing the maximum value of the number of optical bits with a reference value to determine the position of the hole edge with respect to a reference plane.