CN117168389A - On-line detection device and method for screw thread rolling machine - Google Patents

Abstract

The invention relates to an on-line detection device and method for a screw thread rolling machine, comprising the following steps: the two openable and closable stoppers are arranged on the left side and the right side of the material conveying guide rail, a notch is arranged on the workpiece facing side of the stoppers, a groove formed by the notch can accommodate 1/3-1/2 of the diameter of a workpiece when the two stoppers are folded, a rubbing block which can stretch out and draw back along the direction perpendicular to the moving direction of the workpiece and rub the workpiece in the groove is arranged on the opposite side of the groove, and a measuring sensor is arranged on the rubbing block. The invention utilizes the guide rail conveying chain of the bolt workpiece, a stop block is arranged on the conveying chain, and a rubbing block is adopted to rub the workpiece so as to detect the straightness of the workpiece. The simple mechanism is used for rapidly detecting the bending degree of the workpiece on line after heat treatment, and the influence on thread rolling or straightening processing caused by overlarge bending is avoided. Because the detection speed is high, each workpiece can be detected, the rapid rhythm of a thread or straightening processing machine can be completely kept up, the rapid workpiece processing rhythm is not influenced, and the requirement of high speed and accuracy is met.

Description

On-line detection device and method for screw thread rolling machine

Technical Field

The invention relates to an on-line detection device and method of a screw thread rolling machine, in particular to a mechanical measurement device and method, which are used for rapidly detecting and measuring screw parts of all workpieces on a conveying chain in the machining process of the thread rolling machine.

Background

With the improvement of the product quality, the quality requirement of the bolt is continuously improved, and the outer diameter measurement is required to be carried out on the screw rod parts of all workpieces before or after the bolt is used for processing the threads, so that the diameter tolerance after the thread processing is ensured to be within the design range. In addition, the rod-shaped work is liable to bend after heat treatment, and alignment is required before thread working. However, once the workpiece with larger curvature enters the processing station, not only qualified products can not be processed, but also the processing tool can be influenced, and the processing straightening plate or the thread rolling plate can be seriously damaged, even the processing equipment is damaged. To improve the quality of the machining and to prevent damage to the tooling, it is preferable to check all the workpieces one by one before the threads are machined or straightened. However, bolt machining is a highly automated, very large scale machining process, with the machining cadence of one bolt generally being completed in one to a few seconds. With such a processing rhythm, it is impossible to detect the workpieces one by one using a human. Therefore, how to detect screw workpieces one by one with the rapid pace of thread processing is a problem to be solved.

Disclosure of Invention

In order to overcome the problems in the prior art, the invention provides an online detection device and method for a screw thread rolling machine. The device and the method utilize the stop block to stop the workpiece moving on the conveyor chain slide rail, and then rub the workpiece to measure the equivalent diameter change of the workpiece before and after rubbing, and if the equivalent diameter change is too large, the workpiece is proved to be bent greatly and is a disqualified product.

The purpose of the invention is realized in the following way: an on-line detection device of a screw thread rolling machine, comprising: the two blocks which are arranged at the left side and the right side of the material conveying guide rail and can be opened and closed are provided with notches at the sides facing the workpiece, a groove formed by the notches can accommodate 1/3-1/2 of the diameter of the workpiece when the two blocks are folded, a rubbing block which can stretch out and draw back along the direction perpendicular to the moving direction of the workpiece and rub the workpiece in the groove is arranged at the side opposite to the groove, and a measuring sensor is arranged on the rubbing block.

Furthermore, the notch is a straight line inclined notch or a circular arc notch, and the two stop blocks are folded to form a V-shaped groove or a U-shaped groove.

Further, the notch is provided with at least one row of rollers.

Furthermore, the end part of the rubbing block is provided with an inclined plane.

Further, the rubbing block is divided into a transverse moving block perpendicular to the moving direction of the workpiece and a longitudinal moving block connected to the transverse moving block and capable of moving perpendicular to the moving direction of the transverse moving block, and the measuring sensor is arranged on the longitudinal moving block.

Further, the longitudinal movement block is maintained in an extended state by a spring, and a locking device capable of locking the position of the longitudinal movement block when the spring is in a compressed state is arranged.

Furthermore, a positioning block capable of stretching is further arranged behind the stop block, and the stretching direction of the positioning block is perpendicular to the movement direction of the workpiece.

An online detection method for screw workpieces by using the device comprises the following steps:

step 1, a workpiece enters: a single screw workpiece slides down along a material conveying slideway;

step 2, clamping: the two stop blocks are folded to block the workpiece which slides downwards, and the workpiece enters a groove formed by the two stop block gaps;

step 3, rubbing: the transverse moving block of the rubbing block stretches out, the longitudinal moving block is retracted and locked under the extrusion of the workpiece, and meanwhile, the workpiece in the groove is rubbed, and the workpiece is rubbed to rotate by an angle around the rotation center line;

step 4, measuring: the sensor measures the diameter size change before and after the workpiece rotates, if the diameter size change is larger than the specified size change, the workpiece is judged to be unqualified, and the unqualified workpiece is separated; if the judgment is qualified, entering the next step;

step 5, further processing the workpiece: the workpiece is further subjected to dimension measurement or enters a thread rolling station to finish detection work.

Further, the rubbing workpiece rotates around the rotation center line by 60-120 degrees.

Further, the further dimension measurement of the workpiece comprises the following substeps:

step 1, extending a positioning block;

sub-step 2, positioning the workpiece: the stop block is retracted, so that the workpiece in the groove moves forwards for a small distance and is blocked by the positioning block;

step 3, the locking facility is opened, so that the longitudinal movement blocks extend out by the same small distance;

and 4, accurately measuring the diameter of the workpiece by using the sensor.

The invention has the advantages and beneficial effects that: the invention utilizes the guide rail conveying chain of the bolt workpiece, a stop block is arranged on the conveying chain, and a rubbing block is adopted to rub the workpiece so as to detect the straightness of the workpiece. The simple mechanism is used for rapidly detecting the bending degree of the workpiece on line after heat treatment, and the influence on thread rolling or straightening processing caused by overlarge bending is avoided. Because the detection speed is high, each workpiece can be detected, the rapid rhythm of the thread and straightening processing machinery of the thread rolling machine can be completely kept up, the rapid workpiece processing rhythm is not influenced, and the requirement of high speed and accuracy is met.

Drawings

The invention is further described below with reference to the drawings and examples.

FIG. 1 is a schematic view of a method of an apparatus according to an embodiment of the present invention, wherein the method is a schematic view of an open state of a stopper;

FIG. 2 is a schematic view of a method of the apparatus according to an embodiment of the present invention, wherein the method is a schematic view of a closed state of a stopper;

FIG. 3 is a schematic view of the apparatus according to the embodiment of the present invention, and is a view in direction A in FIG. 1;

FIG. 4 is a schematic diagram of an apparatus for measuring straightness of a workpiece according to an embodiment of the present invention;

FIG. 5 is an enlarged view of a V-shaped groove formed by the straight line inclined notch of the second and third embodiments of the present invention, which is shown in FIG. 2;

FIG. 6 is a U-shaped groove formed by the arc-shaped notches of the second and third embodiments of the present invention;

FIG. 7 is a schematic view of a rubbing block according to a fifth embodiment of the invention, in a compressed state of the longitudinal moving block;

FIG. 8 is a schematic view of a rubbing block according to a fifth embodiment of the invention, in which the longitudinal moving block is extended;

Detailed Description

Embodiment one:

the embodiment is an on-line detection device of a screw thread rolling machine, as shown in fig. 1, 2 and 3. The embodiment comprises the following steps: two openable and closable stoppers 201 and 202 mounted on the left and right sides of the material conveying guide rail 1, notches 2021 and 2022 are formed on the sides of the stoppers 2 facing the workpiece, a groove 203 formed by the notches can accommodate 1/3-1/2 of the diameter of the workpiece 3 (the workpiece is indicated by a dotted line in the figure), a rubbing block 4 capable of stretching and rubbing the workpiece in the groove along the direction perpendicular to the moving direction of the workpiece is arranged on the opposite side of the groove, and a measuring sensor 5 is arranged on the rubbing block.

The material conveying guide rail is a common conveying chain in bolt processing and comprises two parallel rails. The track may be two thin bars or may be sheet-like, as shown in fig. 3.

The shoulder of the bolt head of the workpiece is hung on the rail, the bolt rod is hung between the two rails, and the rail is inclined according to the transportation requirement, so that the workpiece can automatically slide down along the rail by means of gravity. In this embodiment, a section of relatively clear position is selected on the lower sliding rail, and a stop block, a rubbing block and a sensor are provided to measure whether the screw straightness of the workpiece meets the requirement or not, and also to measure the diameter of the screw part of the workpiece accurately.

The device is mainly used for detecting the straightness of the workpiece screw rod part, and adopts the mode that the workpiece screw rod part is accommodated in a groove by utilizing the groove capable of accommodating the outer circular surface of the workpiece screw rod, and the workpiece is rubbed to rotate in the groove, so that the equivalent diameter change of the workpiece before and after rotation is compared, and if the straightness of the workpiece is qualified, the equivalent outer diameter change is not large; if the workpiece is bent beyond the desired, the equivalent diameter will react more. The equivalent diameter as used herein refers to the dimensional and form tolerance of the screw portion of the workpiece and the diameter variation that occurs when measured together. When the form and position tolerance (mainly straightness) is large, that is, when the workpiece is relatively bent, the equivalent diameter is large in difference from the dimension diameter, and when the form and position tolerance is small, the equivalent diameter is close to the dimension diameter.

The equivalent diameter measurement requirement is to measure the diameter of the entire length of the workpiece. For the measurement of equivalent diameter of the shank portion of a bolt work, it is required that the length of the measurement groove accommodating the shank portion of the work should be adapted to the length of the shank portion of the work, or be equal, or the work be slightly longer, or the groove be slightly longer, but not differ too much, as shown in fig. 4. The length of the groove 203 is slightly shorter than the length of the workpiece in fig. 4, but is sufficient to measure the length of the workpiece. As shown in FIG. 4, the screw portion of the workpiece is curved more (as the workpiece curvature in FIG. 4 is exaggerated for purposes of illustration) in that the equivalent diameter D of the workpiece is significantly greater than the dimensional diameter D of the workpiece ₁ When the workpiece is rotated 90 degrees, the equivalent diameter and the size diameter of the workpiece are equal, as shown in figure 3,

the two stop blocks are strip-shaped blocks which are respectively arranged at the left side and the right side of the guide rail and are respectively folded from the two sides of the guide rail to the middle, as shown by an arrow a in fig. 1, so that the stop block for the workpiece is formed. The end of the blocking piece is provided with a notch to accommodate the screw portion of the piece. The notch may have various shapes, but is commonly used as an inclined surface or an arc surface. The inclined surfaces of the two block notches form a V-shaped groove when being folded, and the V-shaped groove is a common positioning shape of the outer circular surface. The notch of the two stop blocks can also be two arc surfaces, and when the two arc surfaces are folded, a semicircular groove is formed.

The rubbing block is arranged on one side of the track, and when the workpiece enters the groove formed by folding the check blocks, the rubbing block moves along the direction of an arrow b in fig. 1, one surface of the rubbing block contacts with the outer circular surface of the workpiece and drives the workpiece to rotate around the rotation central axis (the direction of an arrow c in fig. 2) so as to judge whether the straightness of the screw part of the workpiece is larger than the tolerance range. In order to reduce the friction force during the rotation of the workpiece, rolling bodies can be arranged on the notch of the stop block.

The sensor is used for detecting the equivalent diameter size change before and after the workpiece is rubbed and judging the straightness of the workpiece, and the sensor can adopt various sensors such as strain, angle measurement and the like.

The present embodiment is slightly modified to also be used to more accurately measure dimensional tolerances of the diameter of the workpiece screw portion. And a positioning block is arranged at the downstream (rear) of the stop block, after the straightness judgment of the workpiece is finished, the stop block is removed, the workpiece moves forward a little to block the forward path by the positioning block, and at the moment, the rubbing block also moves correspondingly a little forward, so that the size and the diameter of the screw part of the workpiece can be accurately measured as long as the sensor is accurately positioned. The device can be used for carrying out on-line on the workpieces with screw threads (with threads) after thread rolling processing, namely directly removing the stop blocks, blocking the falling workpieces by the positioning blocks, and carrying out accurate dimension measurement so as to classify the workpieces after thread rolling according to tolerance and realize automatic on-line control on the quality of the workpieces.

It should be noted that "front", "rear", "left", "right", "upstream", "downstream" in this embodiment and the following embodiments are determined according to the movement direction of the workpiece, that is: the element contacted first in the moving direction of the workpiece is 'front' or 'downstream', and the element contacted later is 'rear' or 'downstream'; the work piece was simulated as a vehicle that was driven forward, and "left", "right" were determined conventionally for vehicles.

Embodiment two:

the present embodiment is an improvement of the above embodiment, and is a refinement of the above embodiment about the notch, where the notch is a straight inclined notch or a circular arc notch, and the two blocks are folded to form a V-shaped groove or a U-shaped groove, as shown in fig. 3 and 4.

The blocks on the left side and the right side move towards the middle at the same time and fold in the middle of the guide rail, and the straight line inclined notch (corresponding to chamfer angle) on the stop block forms a V-shaped groove, as shown in figure 3, or as shown in figure 4, the arc-shaped notch forms a U-shaped groove. Fig. 3 and 4 show enlarged views at point B of the removal guide rail of fig. 2.

Embodiment III:

the embodiment is a modification of the above embodiment, and is a refinement of the above embodiment about the notch, where at least one row of rollers 6 are disposed at the notch on the stop block, as shown in fig. 5 and 6.

The roller is used for changing sliding friction between the workpiece screw rod part and the supporting point into rolling friction when the supporting point of the workpiece screw rod part is a stop block at two sides, so that the workpiece is easier to roll and rotate. As shown in fig. 5 and 6, the roller is disposed at a position where the straight inclined notch or the circular arc notch contacts the workpiece.

Since fig. 5 and 6 are top views, the thickness of the stopper cannot be represented, and thus the row of rollers means that the rollers extend along the thickness of the stopper, but only one roller, or a row of rollers, is visible in fig. 5 and 6.

Embodiment four:

the present embodiment is a modification of the above embodiment, and is a refinement of the above embodiment about the rubbing block, where the end of the rubbing block is provided with an inclined plane 401, as shown in fig. 5 and 6.

When the rubbing block moves along the arrow b (see fig. 5 and 6), a rubbing action is generated on the workpiece, and the inclined surface at the end of the rubbing block can gradually strengthen the rubbing force, so that the workpiece can rotate more easily.

Fifth embodiment:

the present embodiment is a modification of the above embodiment, and is a refinement of the above embodiment about a rubbing block, where the rubbing block is divided into a transverse moving block 402 perpendicular to the moving direction of the workpiece, and a longitudinal moving block 403 connected to the transverse moving block and capable of moving perpendicular to the moving direction of the transverse moving block, and the measuring sensor is disposed on the longitudinal moving block, as shown in fig. 7 and 8.

The rubbing block is divided into two parts, and one part moves transversely, wherein the transverse movement refers to the movement direction of the rubbing block and the movement direction perpendicular to the movement direction of the workpiece on the guide rail, namely the arrow b direction in fig. 7 and 8, which is consistent with the movement direction of the rubbing block entering the workpiece rubbing position and rubbing the workpiece in fig. 2 and 3, namely the movement of the rubbing block to perform the station and the movement of the rubbing workpiece. The longitudinal movement refers to that the rubbing block can move along the movement track of the workpiece so as to provide pressure on the workpiece, as indicated by an arrow d in fig. 7 and 8.

When the rubbing block is in contact with the workpiece, the workpiece is rubbed by the inclined surface on the rubbing block, and a spring can be arranged on the longitudinal movement for adjusting the force so that the rubbing block can compress the workpiece and control the force for compressing the workpiece, and meanwhile, the device can be prepared for accurately measuring the diameter of the workpiece.

Example six:

this embodiment is a modification of the above embodiment, and is a refinement of the above embodiment with respect to a longitudinal movement block, where the longitudinal movement block is provided with a spring that maintains an extended state, and a locking device 405 that can lock the position of the longitudinal movement block when the spring is in a compressed state, as shown in fig. 7 and 8.

The springs in fig. 7 and 8 are in the form of pressure springs to provide pressure to the workpiece, and in order to utilize the pressure provided by the inclined surface of the rubbing block in the rubbing process, a locking device can be arranged between the longitudinal moving block and the transverse moving block, namely, the longitudinal moving block and the transverse moving block can not move relatively in the rubbing process, the pressure of gradually lifting the workpiece by the inclined surface of the rubbing block is fully utilized, and after the pressure reaches a certain degree, the locking mechanism is released for measurement, so that the effect of detecting the straightness of the workpiece is achieved.

Embodiment seven:

the present embodiment is an improvement of the foregoing embodiment, and is a refinement of the foregoing embodiment about the stop, where a positioning block 7 capable of extending and contracting is further disposed behind the stop, and the extending and contracting direction of the positioning block is perpendicular to the moving direction of the workpiece, as indicated by arrow e in fig. 7 and 8.

The positioning block is also a telescopic moving piece and is mainly used for measuring the size and the diameter of a workpiece. After the workpiece passes the bending detection, a relatively accurate dimensional measurement of the workpiece can be made. For diameter measurement, two opposite points of the outer circle are required, but no V-shaped groove or U-shaped groove can provide such measurement, so this embodiment adopts a positioning block, i.e. a plane is provided, to perform accurate size measurement relative to two opposite measurement points formed on the rubbing block.

The positioning block can extend onto the guide rail after the workpiece is bent to block the forward path of the workpiece, the stop block is retracted, the workpiece moves forward a little and is blocked by the positioning block, the longitudinal moving block on the rubbing block extends out at the moment, so that the longitudinal moving block maintains the pressure on the workpiece, as shown in fig. 8, and the diameter size and tolerance of the workpiece can be obtained by using a relative measurement method.

Example eight:

the embodiment is an online detection method for a screw workpiece by using the device described in the embodiment, and the method comprises the following steps:

step 1, a workpiece enters: a single screw workpiece slides down the feed chute.

The workpieces are sometimes positioned one next to the other or at a distance from each other while they are in orbital motion. This embodiment requires that the workpiece be spaced apart for access to the inspection to provide a short period of time for inspection of the workpiece.

Step 2, clamping: the two stop blocks are closed to block the workpiece which slides downwards, and the workpiece enters the groove formed by the two stop block notches.

When the workpiece moves to the vicinity of the two stop blocks, the two stop blocks are folded to form a V-shaped groove or a U-shaped groove, the workpiece is blocked from going to the way, and the workpiece enters the V-shaped groove or the U-shaped groove. The workpiece entering the V-groove or U-groove corresponds to positioning the workpiece for measurement.

Step 3, rubbing: the transverse moving block of the rubbing block extends out, and the longitudinal moving block is retracted and locked under the extrusion of the workpiece, and meanwhile, the workpiece in the groove is rubbed, so that the workpiece rotates by an angle around the rotation center line.

The purpose of rubbing the workpiece is to judge the straightness of the workpiece, if the straightness of the workpiece meets the requirement, the equivalent diameter change before and after rubbing is not large, otherwise, when the equivalent diameter change after rubbing is large, the bending large angle of the workpiece is indicated, that is, the straightness of the screw part of the workpiece does not meet the requirement.

Step 4, measuring: the sensor measures the diameter size change before and after the workpiece rotates, if the diameter size change is larger than the specified size change, the workpiece is judged to be unqualified, and the unqualified workpiece is separated; if the judgment is qualified, the next step is carried out.

The measuring process is actually started when the rubbing block starts to contact the workpiece, if a stress pressure sensor is adopted, the equivalent diameter change of the workpiece before and after being rubbed can be judged by measuring the pressure change of the rubbing block on the workpiece before and after being rubbed, and therefore whether the curvature of the workpiece is qualified is judged.

Step 5, further processing the workpiece: the workpiece is further subjected to dimension measurement, or the detection work is finished after entering the thread rolling station.

After the workpiece is rubbed, the straightness of the workpiece can be judged through the measuring result of the sensor, after the straightness of the workpiece is judged, if the straightness of the workpiece is within a qualified range, the thread can be continuously processed or the workpiece can be straightened, and if the straightness is unqualified, the unqualified workpiece is separated from the processing sequence. In order to improve the machining precision, after the straightness of the workpiece is detected, the workpiece is further measured in diameter and size, so that better data support is provided for the thread rolling process of the workpiece, and the machining precision is improved. There are various ways of measuring, and the diameter and size of the workpiece are measured by using the facilities for detecting the straightness of the workpiece.

Example nine:

the embodiment is an improvement of the embodiment, and is a refinement of the rotation angle of the rubbing workpiece around the rotation center line, wherein the rotation angle of the rubbing workpiece around the rotation center line is 60-120 degrees.

In general, the bolt blank workpiece after hot working is easy to bend, namely the screw rod parts are bent to each other, the deformation is easy to judge, and the workpiece is rotated by 90 degrees by rubbing the workpiece in the stop block, so that the change of the equivalent diameter of the screw rod can be obviously sensed. If the screw part of the workpiece is deformed in a wave shape, the mode that the rubbing workpiece rotates 90 degrees can be used for judging the completeness of the workpiece, but the condition of wave bending is less, and most of the wave bending is arc bending.

Example ten:

this embodiment is a modification of the above embodiment in that the above embodiment is a refinement of further dimensional measurements made with respect to the workpiece.

The measuring of the size of the workpiece is mainly to measure the diameter and tolerance of the screw part of the workpiece, and as the diameter of the workpiece is measured, two corresponding points on the diameter of the workpiece are needed to be found, two parallel lines are arranged at the two points, and the two parallel lines are perpendicular to the diameter line, so that the diameter of the workpiece can be measured only by the two parallel lines. For this purpose, the present embodiment employs a rubbing block and a positioning block parallel to the rubbing block, and the rubbing block itself is a workpiece diameter line perpendicular to the direction of movement of the workpiece (after rubbing, the bevel has passed through the workpiece and the rear portion has no bevel), so that the diameters of the screw portions of the workpiece can be accurately measured by two parallel lines (two planes of the rubbing block and the positioning block). The further dimension measurement of the workpiece according to this embodiment comprises the following sub-steps:

step 1, extending a positioning block;

the locating block sets up in the rear of dog, therefore the locating block still can not exert an influence to the work piece under the circumstances that the dog was closed, consequently, in order to save time when the dog stretches out, the locating block also can stretch out.

Sub-step 2, positioning the workpiece: the stop block is retracted, so that the workpiece in the groove moves forwards for a small distance and is blocked by the positioning block.

In order to solve the problem that the positioning of the V-shaped groove and the U-shaped groove is not accurate enough, the positioning block is used for replacing the V-shaped groove and the U-shaped groove to form a reference for measuring the diameter, and the diameter of the workpiece is measured by a relative measuring method. However, after the two stop blocks are separated, the workpiece loses the support of the stop blocks and naturally falls down, and forwards advances for a small distance, but is blocked by the positioning blocks to go.

And 3, opening the locking facility to enable the longitudinal movement block to extend out by the same small distance.

The locking means are normally locked during the thread rolling process so that the lateral and longitudinal moving blocks are fixed together, creating a rubbing screw action, but when the workpiece falls towards the positioning block, the rubbing block should follow, at which point the locking means are unlocked, allowing the longitudinal moving block to follow the workpiece forward and move forward under the action of the spring, as indicated by arrow d in fig. 7, 8.

And 4, accurately measuring the diameter of the workpiece by using the sensor.

The sensor measures the workpiece accurately and calculates the diameter of the workpiece accurately by means of comparison of databases and the like.

Finally, it should be noted that the above is only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred arrangement, it should be understood by those skilled in the art that the technical solution of the present invention (such as the dynamic movement mode of each moving member, the form and application mode of the sensor, the sequence of steps, etc.) may be modified or replaced equivalently, without departing from the spirit and scope of the technical solution of the present invention.

Claims (10)

1. An on-line detection device and method for a screw thread rolling machine is characterized by comprising the following steps: the two blocks which are arranged at the left side and the right side of the material conveying guide rail and can be opened and closed are provided with notches at the sides facing the workpiece, a groove formed by the notches can accommodate 1/3-1/2 of the diameter of the workpiece when the two blocks are folded, a rubbing block which can stretch out and draw back along the direction perpendicular to the moving direction of the workpiece and rub the workpiece in the groove is arranged at the side opposite to the groove, and a measuring sensor is arranged on the rubbing block.

2. The detecting device according to claim 1, wherein the notch is a straight line inclined notch or a circular arc notch, and the two stoppers are folded to form a V-shaped groove or a U-shaped groove.

3. The device of claim 2, wherein the notch is provided with at least one row of rollers.

4. A testing device according to claim 3, wherein the end of the rubbing block is provided with a bevel.

5. The detecting device for detecting the movement of a workpiece as claimed in claim 4, wherein the rubbing block is divided into a transverse moving block perpendicular to the movement direction of the workpiece and a longitudinal moving block connected to the transverse moving block and capable of moving perpendicular to the movement direction of the transverse moving block, and the measuring sensor is provided on the longitudinal moving block.

6. The detecting apparatus according to claim 5, wherein the longitudinal movement block is maintained in an extended state by a spring, and a locking means capable of locking the position of the longitudinal movement block when the spring is in a compressed state is provided.

7. The detecting device according to claim 6, wherein a positioning block capable of stretching and retracting is further arranged behind the stop block, and the stretching and retracting direction of the positioning block is perpendicular to the moving direction of the workpiece.

8. A method for on-line inspection of a screw workpiece using the apparatus of claim 7, the method comprising the steps of:

step 1, a workpiece enters: a single screw workpiece slides down along a material conveying slideway;

step 2, clamping: the two stop blocks are folded to block the workpiece which slides downwards, and the workpiece enters a groove formed by the two stop block gaps;

step 3, rubbing: the transverse moving block of the rubbing block stretches out, the longitudinal moving block is retracted and locked under the extrusion of the workpiece, and meanwhile, the workpiece in the groove is rubbed, and the workpiece is rubbed to rotate by an angle around the rotation center line;

step 4, measuring: the sensor measures the diameter size change before and after the workpiece rotates, if the diameter size change is larger than the specified size change, the workpiece is judged to be unqualified, and the unqualified workpiece is separated; if the judgment is qualified, entering the next step;

step 5, further processing the workpiece: the workpiece is further subjected to dimension measurement, or the station detection work is finished after the workpiece enters the thread rolling.

9. The method according to claim 8, wherein the rubbing member rotates around the rotation center line by an angle of 60 to 120 degrees.

10. The method of claim 9, wherein said further dimensional measurement of the workpiece comprises the sub-steps of:

step 1, extending a positioning block;

sub-step 2, positioning the workpiece: the stop block is retracted, so that the workpiece in the groove moves forwards for a small distance and is blocked by the positioning block;

step 3, the locking facility is opened, so that the longitudinal movement blocks extend out by the same small distance;

and 4, accurately measuring the diameter of the workpiece by using the sensor.