JP2021146735A - Joining method of cover canvas - Google Patents

Abstract

To provide a joining method of a cover canvas, which can more reliably form a molding seam of a stacking allowance within predetermined upper and lower limit values in the cover canvas regardless of a belt type.SOLUTION: There is provided a joining method of a cover canvas, comprising: a step of introducing a rotation amount (estimated required rotation amount) of a drive pulley 3a, which is estimated to be required to move a tip portion 151 of a cover canvas 150 from a predetermined pressing position PP of the cover canvas 150 to a belt ring-shaped body 100 to a predetermined reference position SP; a step of detecting a first distance L1 from a tip position XP to the predetermined reference position SP when the drive pulley 3a rotates the estimated required rotation amount from a time when the tip portion 151 passes through the pressing position PP; a step of calculating a second distance L2 from the tip position XP to a polymerization position LP based on the first distance L1; a step of stopping the drive pulley 3a when the drive pulley 3a rotates a rotation amount R20 corresponding to the second distance L2; and a step of joining the tip portion 151 and a rear end portion 152 of the cover canvas 150 by overlapping thereof.SELECTED DRAWING: Figure 8

Description

The present invention relates to a covering process for covering a belt ring-shaped body with a cover canvas, and relates to a method for joining the cover canvas for superimposing and joining both ends of the cover canvas in the longitudinal direction within a predetermined upper and lower limit values.

As a transmission belt for transmitting power, there is a wrapped V-belt whose surface is covered with a cover canvas in order to ensure vertical crack resistance. The wrapped V-belt is formed, for example, as described below (see, for example, Patent Documents 1 and 2).

Specifically, first, the belt ring-shaped body is wound between a plurality of pulleys, and the belt ring-shaped body traveling between the plurality of pulleys is subjected to skiving treatment for cutting off the corners of the belt ring-shaped body. .. Then, a covering process is performed in which the cover canvas is wrapped around the surface of the belt ring-shaped body that has been subjected to the skive treatment, and the belt ring-shaped body is covered with the cover canvas. As a result, a belt molded body whose surface is covered with a cover canvas is formed. Then, the belt molded body is subjected to a vulcanization treatment to form an elastic wrapped V-belt.

Japanese Unexamined Patent Publication No. 2016-87885 Japanese Unexamined Patent Publication No. 2019-1887773

By the way, as described in Patent Document 2, in the covering process, after the cover canvas is unwound from the canvas feeding portion and cut at a predetermined cutting position, the tip portion (winding start portion) in the longitudinal direction of the cover canvas is used. ) And the rear end (end of winding) are overlapped and joined. The joints at both ends of the cover canvas in the longitudinal direction are referred to as "molding seams".

In order to ensure excellent belt performance, this forming seam is required to be formed in the cover canvas with a stacking allowance within a predetermined upper and lower limit range (hereinafter, also referred to as a predetermined upper and lower limit range). .. For example, if the forming seam is formed with a stacking allowance that is less than the lower limit value of the predetermined upper and lower limit ranges, there is a risk that belt characteristics such as vertical crack resistance cannot be ensured. Further, when the forming seam is formed with a stacking allowance exceeding the upper limit value of the predetermined upper and lower limit ranges, the belt characteristics such as flexibility will be significantly different from other parts, which is not preferable in terms of belt quality. Under these circumstances, it is required that the cover canvas has a forming seam formed with a stacking allowance within a predetermined upper and lower limit range.

Here, even if the same ratio of variation occurs with respect to the belt length of various transmission belts, the longer the belt length (length in the longitudinal direction), the more the belt is used in the molding process such as the covering process. In the ring-shaped body, the permissible range of the belt length with respect to the reference value (that is, the permissible variation of the belt length) becomes large. In particular, since the belt length of the wrapped V-belt is relatively longer than that of other types of transmission belts, the allowable range of the belt length with respect to the reference value is relatively large in the belt ring-shaped body used in the molding process.

However, for example, in the conventional molding method of the belt molded body described in Patent Documents 1 and 2, in the covering process, the cover canvas having a length (wrapping length) predetermined for each belt type is a belt ring-shaped body. Always covered with. As a result, when there is a large variation in the belt length of the belt ring-shaped body to be covered, there is a possibility that the molding seam of the cover canvas is not formed with a stacking allowance within a predetermined upper and lower limit range. In particular, this problem is likely to occur when the belt length of a type of transmission belt having a relatively long belt length (for example, a wrapped V-belt), that is, the belt length of the belt ring-shaped body to be covered is relatively long. Therefore, for example, in the conventional molding method of the belt molded body described in Patent Documents 1 and 2, the type of the belt molded body to be molded is relatively short (for example, belt molding having a belt length of 60 to 75 inches). I had to limit it to the body).

The present invention is for solving the above-mentioned problems, and an object of the present invention is to more reliably form a forming seam of a stacking allowance within a predetermined upper and lower limit values in a cover canvas regardless of the belt type. To provide a method of joining canvas.

(1) In order to solve the above problems, the method of joining the cover canvas according to a certain aspect of the present invention is described in the covering process of covering the belt ring-shaped body traveling between a plurality of pulleys including the drive pulley with the cover canvas. A method for joining a cover canvas in which a front end portion and a rear end portion in the longitudinal direction of the cover canvas are overlapped and joined within a predetermined upper and lower limit values, and the belt traveling between the plurality of pulleys. From a predetermined pressing position where the cover canvas is pressed against the ring-shaped body and the contact of the cover canvas with the belt ring-shaped body is started, the tip end portion and the rear end portion on the outer peripheral surface of the belt ring-shaped body. Is an estimated required amount of rotation of the drive pulley, which is estimated to be required to move the tip portion to a predetermined reference position in the direction opposite to the circumferential direction from the superposition position where and can be overlapped with a predetermined stacking allowance. The derivation step for deriving the rotation amount and the tip portion on the outer peripheral surface of the belt ring-shaped body at the time when the drive pulley rotates the estimated required rotation amount from the time when the tip portion passes the predetermined pressing position. The detection step of detecting the tip position, which is the position of the above, and the first distance, which is the distance from the tip position to the predetermined reference position along the outer peripheral surface of the belt ring, and the first. Based on the distance of 1, the calculation step of calculating the second distance, which is the distance along the outer peripheral surface of the belt ring from the tip position to the overlapping position, and the estimated required rotation amount of the drive pulley. The cover canvas is cut at a stop step for stopping the drive pulley when the rotation amount corresponding to the second distance is rotated from the time when the cover canvas is rotated, and at a predetermined cutting position on the canvas supply path of the cover canvas. At the same time, it has a joining step of superimposing and joining the tip portion and the rear end portion formed by cutting the cover canvas at the polymerization position set based on the predetermined cutting position.

According to this configuration, the first distance from the tip position of the cover canvas when the drive pulley rotates the estimated required rotation amount to a predetermined reference position in the direction opposite to the circumferential direction from the polymerization position is detected. .. Then, a second distance from the tip position to the polymerization position is calculated based on the first distance, and the drive pulley rotates and stops by the amount of rotation corresponding to the second distance. That is, even if the belt length of the belt ring-shaped body varies, the winding length of the cover canvas is adjusted according to the variation before the tip of the cover canvas reaches the overlapping position. Therefore, for example, even when the covering treatment is applied to a type of belt ring-shaped body having a relatively large variation in belt length, the overlapping allowance of the molding seam in the cover canvas within the range of the predetermined upper and lower limit values. Can be formed with. Therefore, regardless of the belt type, it is possible to provide a method for joining the cover canvas, which can more reliably form the molding seam of the overlapping allowance within the range of the predetermined upper and lower limit values in the cover canvas.

(2) Preferably, prior to the detection step, the rotation of the drive pulley is temporarily stopped when the drive pulley rotates the estimated required rotation amount from the time when the tip portion passes the predetermined pressing position. Further, in the detection step, the temporary stop position of the tip portion on the outer peripheral surface of the belt ring-shaped body that has been temporarily stopped due to the temporary stop of the drive pulley is set as the tip portion position. Detected.

According to this configuration, the position of the tip of the cover canvas on the outer peripheral surface of the belt ring is detected in a state where the rotation of the drive pulley is temporarily stopped, that is, a state in which the movement of the cover canvas is suspended. Therefore, the position of the tip of the cover canvas can be detected more accurately.

(3) Preferably, the polymerization position is the outer circumference of the belt ring-shaped body, which is the distance between the predetermined cutting position and the predetermined pressing position along the canvas supply path minus the predetermined stacking allowance. It is provided at a position along the surface that is traced back from the predetermined pressing position in a direction opposite to the circumferential direction.

According to this configuration, the distance between the rear end portion formed by being cut at a predetermined cutting position on the canvas supply path and the predetermined pressing position along the canvas supply path is a belt from the predetermined pressing position to the polymerization position. The distance is obtained by adding a predetermined overlapping allowance to the distance along the outer peripheral surface of the ring-shaped body. Therefore, by simply superimposing the rear end portion formed by cutting at a predetermined cutting position on the canvas supply path on the tip portion as it is, the distance between the rear end portion and the polymerization position becomes a predetermined stacking allowance, and the cover canvas A molding seam is formed that falls within the predetermined upper and lower limit values. Therefore, both ends of the cover canvas can be accurately overlapped with a predetermined overlapping allowance, and a molding seam of the overlapping allowance within a predetermined upper and lower limit values can be easily formed.

(4) Preferably, in the detection step, the tip portion on the outer peripheral surface of the belt ring-shaped body is detected based on the image data acquired by the vision sensor including the predetermined reference position in the photographing region. The first distance is detected.

According to this configuration, even when the thickness of the belt ring-shaped body changes depending on the type of the belt ring-shaped body, the tip end portion of the cover canvas on the outer peripheral surface of the belt ring-shaped body can be easily detected.

For example, a configuration is also conceivable in which a laser sensor is used to detect the tip of the cover canvas on the outer peripheral surface of the belt ring. Specifically, the tip of the cover canvas is detected by receiving the reflected wave of the laser emitted toward the outer peripheral surface of the belt ring and calculating the distance based on the time from the emission of the laser to the reception. It is also possible to do. However, the data acquired by the laser sensor is one-dimensional data (distance data to the object). In this case, in order to be able to detect the tip of the cover canvas when the thickness of the belt ring-shaped body changes, a complicated arithmetic program for detecting the change point of the reference distance to the object is required.

On the other hand, the image data acquired by the vision sensor is two-dimensional data. Therefore, even when the thickness of the belt ring-shaped body changes, that is, even when the reference distance to the object changes, the tip portion of the cover canvas can be detected without requiring a complicated calculation program.

Therefore, according to the above configuration, the tip portion of the cover canvas can be easily detected.

(5) Preferably, the predetermined reference position is provided in the latter half of the orbit of the belt ring-shaped body traveling between the plurality of pulleys and starting from the predetermined pressing position.

According to this configuration, a section for adjusting the winding length of the cover canvas to be wound around the belt ring-shaped body as compared with the case where a predetermined reference position is provided in the first half portion of the circumference of the belt ring-shaped body traveling between the plurality of pulleys. Becomes shorter. Therefore, the accuracy of adjusting the winding length of the cover canvas can be ensured.

(6) Preferably, in the derivation step, the estimated required rotation amount is derived based on a predetermined peripheral length of the belt ring-shaped body and the peripheral length of the drive pulley.

According to this configuration, a more accurate estimated required rotation amount can be derived according to the type of the belt ring-shaped body to be covered.

According to the present invention, it is possible to provide a method for joining a cover canvas, which can more reliably form a molding seam of a stacking allowance within a predetermined upper and lower limit values in the cover canvas regardless of the belt type.

It is a figure which shows typically the molding apparatus of the belt molded body for realizing the joining method of the cover canvas which concerns on one Embodiment of this invention. It is a figure for demonstrating the shape of the belt ring-shaped body, (A) is the outline view of the belt ring-shaped body, (B) is the cross-sectional view in line IB-IB of (A). It is a figure for demonstrating the shape of the belt molded body, (A) is the outline view of the belt molded body, (B) is the sectional view in line IIB-IIB of (A). It is a schematic diagram for demonstrating the structure of a covering process. It is a schematic diagram for demonstrating the positional relationship with the belt ring-shaped body traveling between a vision sensor, an illumination part, and a pair of pulleys. (A) is a block diagram of an operation panel, and (B) is a block diagram of a control panel. It is a flowchart which shows the joining method of a cover canvas. It is a schematic diagram for demonstrating the adjustment of the winding length of a cover canvas. It is a schematic diagram for demonstrating the amount of deviation of the tip portion position of a cover canvas with respect to a predetermined reference position, and (A) the figure which shows typically the photographed image which image | photographed the tip portion of the cover canvas at the time of a covering process, (B). ) It is a figure which shows typically the model image of the tip part of the cover canvas. It is a schematic diagram which shows the state which the front end part and the rear end part of a cover canvas are overlapped. It is a figure which shows the evaluation in each of the case where the joining method of the cover canvas which concerns on one Embodiment of this invention is adopted, and the case where the joining method of the cover canvas which concerns on a comparative example is adopted.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[Rough configuration of molding equipment for belt molded products]
FIG. 1 is a diagram schematically showing a molding apparatus 1 of a belt molded body for realizing a method of joining a cover canvas according to an embodiment of the present invention. The molding device 1 is configured as a device for molding a belt molded body. The belt molded body is formed as a material constituting a transmission belt (for example, a wrapped V-belt) that transmits power, and by subjecting the belt molded body to a vulcanization treatment, an elastic transmission belt can be obtained. It is formed. As will be described later, the belt molded body is formed by subjecting the belt ring-shaped body to a covering treatment or the like.

In the following, before explaining the detailed configuration of the molding apparatus 1, the belt ring-shaped body and the belt molded body will be described in order.

[Belt ring]
2A and 2B are views for explaining the shape of the belt ring-shaped body 100, FIG. 2A is an outline view of the belt ring-shaped body 100, and FIG. 2B is FIG. 2A. It is sectional drawing in IB-IB line.

As shown in FIG. 2B, the belt ring-shaped body 100 has a core sandwiched between an unvulcanized compressed rubber layer 101, an unvulcanized stretched rubber layer 103, and these rubber layers 101 and 103. It has a line 102 and. The belt ring-shaped body 100 is formed in an endless loop shape having a predetermined peripheral length (for example, 60 to 105 inches). The width w of the belt ring-shaped body 100 is, for example, about 13 mm (millimeters), and the thickness t of the belt ring-shaped body 100 is, for example, about 8 mm.

As shown in FIG. 2B, for example, the belt ring-shaped body 100 has a substantially rectangular cross-sectional shape (a cross-sectional shape perpendicular to the longitudinal direction). The cross-sectional shape of the belt ring-shaped body 100 is not limited to this, and may be a hexagonal shape, a trapezoidal shape, or the like.

The compressed rubber layer 101 is a loop-shaped rubber layer having a predetermined peripheral length, and has a rectangular cross-sectional shape as shown in FIG. 2 (B). The compressed rubber layer 101 is made of, for example, natural rubber (NR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), or the like. The compressed rubber layer 101 is provided as a rubber layer on the inner peripheral side of the belt ring-shaped body 100.

The stretched rubber layer 103 is a loop-shaped rubber layer having a peripheral length substantially the same as that of the compressed rubber layer 101, and has a rectangular cross-sectional shape as shown in FIG. 2 (B). There is. The stretched rubber layer 103 is superposed on the compressed rubber layer 101 with the core wire 102 sandwiched between the stretched rubber layer 103 and the compressed rubber layer 101. The width of the stretched rubber layer 103 is the same as that of the compressed rubber layer 101, while the thickness of the stretched rubber layer 103 is formed to be thinner than that of the compressed rubber layer 101. Like the compressed rubber layer 101, the stretched rubber layer 103 is made of natural rubber (NR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), or the like. The stretchable rubber layer 103 is provided as a rubber layer on the outer peripheral side of the belt ring-shaped body 100.

The core wire 102 is held in a state of being sandwiched between the compressed rubber layer 101 and the stretched rubber layer 103. The core wire 102 is provided over the entire peripheral length of each of the rubber layers 101 and 103. The core wire 102 is provided so as to extend along the circumferential direction of the rubber layers 101 and 103 (specifically, spirally with respect to the circumferential direction). As a result, the core wire 102 functions as a reinforcing member for preventing the belt ring-shaped body 100 from breaking. The core wires 102 are arranged so as to be evenly spaced from each other along the width direction of the rubber layers 101 and 103. As the core wire 102, for example, a wire such as a polyester fiber, a nylon fiber, or an aramid fiber is used. In the cross-sectional view of FIG. 2B, the belt ring-shaped body 100 in which the number of arrangements of the core wires 102 is “8” is exemplified, but the density of the arrangement of the core wires 102 is not limited to this. Although not shown, an adhesive rubber layer may be provided on the surface of the compressed rubber layer 101 on the core wire 102 side and the surface of the stretched rubber layer 103 on the core wire 102 side.

Since the belt ring-shaped body 100 having the above-described configuration is in an unvulcanized state, its surface portion has adhesiveness and low elasticity, and it is a member that is relatively difficult to handle. be.

[Belt molded body]
FIG. 3 is a diagram for explaining the shape of the belt molded body 200, FIG. 3 (A) is an outline view of the belt molded body 200, and FIG. 3 (B) is a view of FIG. 3 (A). It is sectional drawing in line IIB-IIB.

The belt molded body 200 is molded by subjecting the belt ring-shaped body 100 to a predetermined treatment. Specifically, the belt molded body 200 is molded by subjecting the belt ring-shaped body 100 to a skiving treatment and a covering treatment. The skive treatment is a treatment for cutting off the corner portion 101a (see FIG. 2B) of the compressed rubber layer 101 in the belt ring-shaped body 100. The covering treatment is a treatment in which the cover canvas 150 is wrapped around the belt ring-shaped body 100 that has been subjected to the skive treatment to cover it. The belt molded body 200 according to the present embodiment is composed of a two-layer cover canvas 150 having a lower cover 106 and an upper cover 107. The belt molded body 200 may be composed of a single-layer cover canvas 150 without being limited to this.

As shown in FIG. 3B, the belt molded body 200 has, for example, a substantially trapezoidal cross-sectional shape. Further, the belt molded body 200 is a joint portion for joining the longitudinal end portions of the cut cover canvas 150 at one position in the longitudinal direction, and is a joint portion extending perpendicular to the longitudinal direction. A "molding seam" is provided. In addition, the present invention is not limited to this, and the molding seam may be, for example, a joint portion extending diagonally with respect to the longitudinal direction.

The cover canvas 150 is provided to ensure the vertical crack resistance of a transmission belt such as a wrapped V-belt. In the cover canvas 150, elasticity in the longitudinal direction of the belt is required in order to follow the bending motion of the transmission belt. Therefore, as the cover canvas 150, for example, a canvas formed by applying a rubberizing treatment to a woven fabric in which fibers are woven by crossing at a predetermined angle, a so-called bias canvas, is used. The thickness of the cover canvas 150 is, for example, about 0.6 mm, and the width of the cover canvas 150 is, for example, about 50 mm.

[Detailed configuration of the molding device for the belt molded body]
Next, the detailed configuration of the molding apparatus 1 of the belt molded body 200 will be described again with reference to FIG. The molding apparatus 1 includes a canvas supply mechanism 2, a covering processing unit 3, an operation panel 4, a control panel 5, and the like.

[Structure of canvas supply mechanism]
The canvas supply mechanism 2 is configured to be able to supply the cover canvas 150 from the canvas feeding unit (not shown) to the covering processing unit 3 via the canvas supply path 22. The canvas supply path 22 is configured as a path for supplying the cover canvas 150 along the plurality of rolls 12 from the canvas feeding section to the covering processing section 3 (more specifically, the pressing position PP by the pressing roll 31). ing.

In the following, the canvas supply mechanism 2 of the cover canvas 150 (specifically, the lower cover 106) of one of the two-layer cover canvas 150 (see FIG. 2B) of the lower cover 106 and the upper cover 107. Will be described. However, the canvas supply mechanism 2 of the other cover canvas 150 (specifically, the upper cover 107) has the same configuration. Further, in FIG. 1, the canvas supply mechanism 2 of the lower cover 106 is shown, and the canvas supply mechanism 2 of the upper cover 107 is omitted. Further, in the following, the lower cover 106 will be referred to as a cover canvas 150.

The canvas supply mechanism 2 includes a canvas grip portion 13, a cutting device 14, a material seam detecting portion 16, a path length adjusting portion 17, and the like. At the upstream end of the canvas supply path 22, a canvas feeding portion (not shown) for supplying the cover canvas 150 to the canvas supply path 22 is provided.

The canvas grip portion 13 is configured to be able to grip the cover canvas 150 on the downstream side of the canvas supply path 22 (downstream in the transfer direction of the cover canvas 150). Specifically, the canvas grip portion 13 is configured to grip the cover canvas 150 at the downstream end of the canvas supply path 22. Further, the canvas grip portion 13 is arranged at a position near the covering processing portion 3.

The canvas grip portion 13 is configured to be able to switch between a gripping operation of gripping the cover canvas 150 and an opening operation of releasing the grip of the cover canvas 150 by operating with compressed air supplied from a pressure source (not shown). ing. Specifically, the canvas grip portion 13 has a clamp portion 13a that opens and closes with the supply and discharge of compressed air from the pressure source. A small air cylinder (not shown) for supplying and discharging compressed air from a pressure source is connected to the clamp portion 13a, and the clamp portion 13a opens and closes as the air cylinder operates due to the supply and discharge of compressed air. The operation is performed.

The canvas gripping unit 13 is controlled to grip the cover canvas 150 when the covering process by the covering processing unit 3 is started and when the covering process is completed. Specifically, the canvas grip portion 13 is controlled to release the grip of the cover canvas 150 while the cover ring processing unit 3 is performing the covering process. The control of the canvas grip portion 13 is, for example, operated based on a command from the drive control unit 5a (see FIG. 6B) stored in the control panel 5 described later, and the operation is controlled by the drive control unit 5a. It is configured as follows.

Further, the canvas grip portion 13 is provided with a grip portion open / close detector 13b that detects the opening / closing operation of the clamp portion 13a of the canvas grip portion 13. When the grip portion opening / closing detector 13b detects the opening / closing operation of the clamp portion 13a of the canvas grip portion 13, the detection result is used as a grip portion opening / closing detection signal in the drive control unit 5a of the control panel 5 (see FIG. 6B). It is configured to send. The grip portion open / close detector 13b is configured as, for example, an auto switch attached to the air cylinder.

Further, on the upstream side of the canvas grip portion 13 (upstream side in the transfer direction of the cover canvas 150) in the canvas supply path 22, a roller guide 24 for smoothly transporting the cover canvas 150 to the canvas grip portion 13 is provided. Has been done.

Further, the canvas supply mechanism 2 is provided with a canvas grip portion displacement mechanism 25 for displacing the position of the canvas grip portion 13. The canvas grip portion displacement mechanism 25 is configured to operate based on a command from the drive control unit 5a of the control panel 5 to displace the position of the canvas grip portion 13 with respect to the upper pulley 3a in the covering processing unit 3. ..

The cutting device 14 is configured to be able to cut a portion of the cover canvas 150 gripped by the canvas grip portion 13 on the covering processing portion 3 side at a predetermined cutting position (also referred to as a cut position) CP. The cutting position CP is arranged, for example, at a position near the upper end portion of the upper pulley 3a of the pair of pulleys 3a and 3b. Specifically, as shown in FIG. 8, the cutting position CP covers a predetermined distance L10 from the pressing position PP of the pressing roll 31 (described later) along the canvas supply path 22 on the side opposite to the transfer direction of the canvas 150. It is installed at a position that goes back to.

The cutting device 14 has a scissors-shaped air cutter (not shown) for cutting the cover canvas 150, and operates with compressed air supplied from a pressure source to drive the air cutter to drive the cover canvas 150. It is configured to perform the disconnection operation of.

Further, the cutting device 14 is provided with a cutting detector 14a (see FIG. 1) for detecting the end of the cutting operation of the cover canvas 150. When the disconnection detector 14a detects the disconnection operation of the disconnection device 14, the disconnection detector 14a is configured to transmit the detection result as a disconnection detection signal to, for example, the drive control unit 5a of the control panel 5. The cutting detector 14a includes, for example, a proximity sensor or a displacement sensor that detects the operation of the air cutter of the cutting device 14.

[Material seam detector]
The cover canvas 150 supplied from the canvas feeding section 11 to the covering processing section 3 along the canvas supply path 22 is a portion in which the cover canvas 150 as a material is overlapped and joined at predetermined intervals in the longitudinal direction. A seam 23 is formed. The material seam detecting unit 16 is provided as a mechanism for detecting the material seam 23 in the cover canvas 150 that is fed and conveyed from the canvas feeding unit. By providing the material seam detecting unit 16, it is possible to prevent the material seam 23, which poses a quality problem, from being included in the belt molded body 200.

The material seam detection unit 16 includes a step detection unit 26 and a position detector 27.

The step detection unit 26 is one of the plurality of receiving rolls 12, and is a thickness direction of the material seam 23 passing over the detection roll 12c on the detection roll 12c arranged at a predetermined position on the canvas supply path 22. It is configured as a mechanism to detect the step difference. Specifically, since the material seam 23 is configured as a portion of the cover canvas 150 that is overlapped and joined in the thickness direction, a step is generated in the thickness direction. The step detection unit 26 is configured to detect this step. Further, the above-mentioned predetermined position is a predetermined position on the canvas supply path 22, and is set as a material seam detection position MP in which the material seam detection unit 16 detects the material seam 23.

The position detector 27 is configured as a detector capable of tracking the current position on the canvas supply path 22 of the material seam 23 detected as a step by the step detection unit 26. More specifically, the position detector 27 is provided as an encoder that detects the rotation angle of the detection roll 12c. Further, the position detector 27 is configured to transmit the detected rotation angle detection signal S27 of the detection roll 12c to, for example, the arithmetic control unit 4a (see FIG. 6A) of the operation panel 4 described later. ing.

[Route length adjustment unit]
The path length adjusting unit 17 moves (displaces) the position of the moving roll 12d, which is one of the plurality of receiving rolls 12 and is arranged on the canvas supply path 22, for each type of the belt molded body 200. It is provided as a mechanism that can adjust the length of the canvas supply path 22.

In the path length adjusting unit 17, when the covering process of a certain type of belt molded body 200 is started, the position of the moving roll 12d is changed in advance based on the control of the drive control unit 5a of the control panel 5, for example. , The length of the canvas supply path 22 is adjusted. At this time, in the path length adjusting unit 17, the length along the canvas supply path 22 from the cutting position CP of the cover canvas 150 to the material seam detection position MP is the length of the cover canvas 150 for one roll of the belt ring-shaped body 100. The canvas supply path 22 is adjusted so as to have a predetermined length slightly longer than the length. Then, in the path length adjusting unit 17, such an operation is executed for each type of the belt molded body 200 to be generated.

[Structure of covering processing unit]
FIG. 4 is a schematic diagram for explaining the configuration of the covering processing unit 3. The cover ring processing unit 3 is configured as a device that executes a cover ring process of winding the cover canvas 150 around the belt ring-shaped body 100 after the skive process and covering the belt ring-shaped body 100. Hereinafter, the configuration of the covering processing unit 3 will be described with reference to FIGS. 1 and 4.

The covering processing unit 3 is configured to include a traveling mechanism having a plurality of pulleys (a mechanism for traveling the belt ring-shaped body 100). The plurality of pulleys have a drive pulley configured to be rotatable around its rotation axis. A belt ring-shaped body 100 is wound around the plurality of pulleys, and the belt ring-shaped body 100 travels between the plurality of pulleys due to the rotation of the drive pulley. Then, the cover canvas 150 supplied from the canvas supply mechanism 2 is wound around the belt ring-shaped body 100 in a state of being wound around the plurality of pulleys to cover the belt ring-shaped body 100.

In the present embodiment, as shown in FIG. 1, the covering processing unit 3 has a pair of pulleys 3a and 3b arranged so as to face each other in the vertical direction (vertical direction), and the pair of pulleys 3a and 3b. One of the pulleys (for example, the upper pulley 3a) is configured as a drive pulley. Here, the pair of pulleys 3a and 3b are arranged to face each other in the vertical direction, but the present invention is not limited to this, and for example, the pair of pulleys 3a and 3b may be arranged to face each other in the horizontal direction. Further, the plurality of pulleys are not limited to the pair of pulleys arranged so as to face each other, and may be, for example, pulleys having three or more axes.

The drive pulley 3a is connected to a traveling mechanism drive unit 3c (see FIG. 1) including an electric motor (for example, a servomotor), and is rotationally driven by the drive of the electric motor. The traveling mechanism drive unit 3c is configured to operate based on a command from the drive control unit 5a of the control panel 5 and to control the operation by the drive control unit 5a. Further, the traveling mechanism driving unit 3c is provided with a detector 3d that detects the rotation angle of the rotation shaft of the electric motor of the traveling mechanism driving unit 3c. Examples of the detector 3d include an encoder. By detecting the rotation angle of the rotation shaft of the electric motor of the travel mechanism drive unit 3c by the detector 3d, the rotation amount of the transmission motor of the travel mechanism drive unit 3c, that is, the rotation amount (rotation number) of the drive pulley 3a is controlled. Will be done. In the schematic view of FIG. 1, the drive pulley 3a and the traveling mechanism driving unit 3c are shown separately, but in reality, the driving pulley 3a and the traveling mechanism driving unit 3c are connected to each other.

As shown in FIG. 4, the covering processing unit 3 has a pressing roll 31, a catcher unit 32, and a pair of bottom-side bent discs 38.

The pressing roll 31 is for pressing the cover canvas 150 against the belt ring-shaped body 100 traveling on the pair of pulleys 3a and 3b. The pressing roll 31 is traveling on the pair of pulleys 3a and 3b by applying a pressing force toward the drive pulley 3a side to the cover canvas 150 at a predetermined pressing position PP (also referred to as a pressing start position). The cover canvas 150 is pressed against the outer peripheral surface of the belt ring-shaped body 100 of the above. As a result, the contact of the cover canvas 150 with the outer peripheral surface of the belt ring-shaped body 100 is started. Then, the side surface side bending roll 34 described below covers the side surface of the belt ring-shaped body 100 with the cover canvas 150, and the back roller 35 covers the inner peripheral surface of the belt ring-shaped body 100 with the cover canvas 150.

Specifically, the catcher portion 32 has a curving roll 33, a side bending roll 34, and a back roller 35. In the catcher portion 32, each component constituting the catcher portion 32 cooperates to wind the cover canvas 150 around the belt ring-shaped body 100.

The curving roll 33 is for bending both side portions in the width direction of the cover canvas 150 pressed against the outer peripheral surface of the belt ring-shaped body 100 by the pressing roll 31 toward the side surface side of the belt ring-shaped body 100 to perform curving. Is.

The side-side bending roll 34 is for pressing a portion of the cover canvas 150 that is bent toward the side surface side of the belt ring-shaped body 100 by the curving roll 33 against the side surface of the belt ring-shaped body 100. Further, the side bending roll 34 is also for bending the outer portion of the cover canvas 150 in the width direction toward the bottom surface (inner peripheral surface) side of the belt ring-shaped body 100.

The back roller 35 is configured to be able to press the back surface (outer peripheral surface) of the cover canvas 150 toward the belt ring-shaped body 100 side. In the covering process, when both end portions of the cover canvas 150 in the width direction are pressed against the side surfaces of the belt ring-shaped body 100 by the side bending roll 34, the central portion of the cover canvas 150 in the width direction is pressed by the back roller 35. It is held down. As a result, the winding wrinkles of the cover canvas 150 can be effectively suppressed.

The pair of bottom-side bent discs 38 is formed by bending a portion of the cover canvas 150 that is bent toward the bottom surface side of the belt ring-shaped body 100 by the side-side bending roll 34 to the bottom surface (inner peripheral surface) of the belt ring-shaped body 100. It is for pressing.

Further, when the covering process for the belt ring-shaped body 100 is completed and the belt molded body 200 is molded, the covering processing unit 3 runs the belt molded body 200 by a traveling mechanism (specifically, a pair of pulleys 3a and 3b). It is configured to be automatically removed from.

[Approximate operation of covering processing unit]
The schematic operation of the covering processing unit 3 will be described with reference to FIG.

First, in the state before the covering process is performed by the covering processing unit 3, the pressing roll 31 is on standby at the standby position P1. Then, when the covering process is performed, the canvas grip portion 13 in a state of gripping the tip portion 151 (in other words, the downstream end portion) of the cover canvas 150 is near the upper end portion of the upper pulley (drive pulley) 3a. Move to. As a result, the tip portion 151 of the cover canvas 150 comes into close contact with the belt ring-shaped body 100.

After that, the pressing roll 31 moves from the standby position P1 to the pressing position PP. As a result, the tip portion 151 of the cover canvas 150 in close contact with the belt ring-shaped body 100 is pressed against the outer peripheral surface of the belt ring-shaped body 100 by the pressing roll 31. After that, the canvas grip portion 13 releases the grip on the cover canvas 150 and retracts to the rear. At this time, the catcher portion 32 and the bottom side bent disc 38 move from their respective standby positions to the covering processing position.

In such a state, the cover canvas 150 is sequentially sent out from the canvas supply path 22 in the circumferential direction of the belt ring-shaped body 100 along with the rotational drive of the drive pulley 3a. Then, the cover canvas 150 is squeezed by the squeeze roll 33 so that the cross-sectional shape becomes substantially U-shaped, and then travels further in the circumferential direction, and the side side bending roll 34, the back roller 35, and the bottom surface are further circulated. The side bent disc 38 is wound around the belt ring-shaped body 100.

Then, after the winding length (winding processing length) adjustment processing described later is executed, when the tip portion 151 of the cover canvas 150 reaches the polymerization position LP (described later), the rotational drive of the upper pulley 3a is stopped. .. The polymerization position LP is a position where the tip portion 151 of the cover canvas 150 and the rear end portion 152 formed by cutting the cover canvas 150 by the cutting device 14 as described later can be overlapped with a predetermined stacking allowance K1. be. This polymerization position LP is set based on a predetermined cutting position CP. Specifically, the polymerization position LP is a belt having a distance L20 (see FIGS. 8 and 10) obtained by subtracting a predetermined stacking allowance K1 from the distance L10 along the canvas supply path 22 between the cutting position CP and the pressing position PP. It is preferable that the ring-shaped body 100 is provided at a position that goes back from the pressing position PP in the direction opposite to the circumferential direction along the outer peripheral surface of the ring-shaped body 100.

Next, after the cover canvas 150 is gripped by the canvas grip portion 13, the cover canvas 150 is cut by the cutting device 14 at a predetermined cutting position CP provided on the belt ring-shaped body 100 side with respect to the gripped portion. NS.

After that, the rear end portion 152 (in other words, the upstream end portion) of the cover canvas 150 formed by cutting the cover canvas 150 by the cutting device 14 is stopped on the polymerization position LP of the cover canvas 150. It is overlapped and joined to the tip portion 151. That is, the winding start portion (tip portion 151) and the winding end portion (rear end portion 152) of the cover canvas 150 are overlapped and joined.

Then, the upper pulley 3a is rotationally driven again, and the remaining cover canvas 150 is wound around the belt ring-shaped body 100, so that the winding of the cover canvas 150 around the belt ring-shaped body 100 is completed. In addition, the above-mentioned operation is executed in both the lower cover 106 and the upper cover 107. Then, the belt molded body 200 (see FIG. 2) is molded by this.

The joints of both ends 151 and 152 in the longitudinal direction of the cover canvas 150 are referred to as "molding seams". In order to ensure excellent belt performance, the forming seam is required to be formed with a stacking allowance within a predetermined upper / lower limit range (hereinafter, also referred to as a predetermined upper / lower limit range) in the longitudinal direction. The predetermined upper and lower limit ranges are the lower limit value obtained by subtracting the predetermined value (for example, 7 mm) from the reference value (for example, 10 mm) of the molding seam (the overlap margin of both ends in the longitudinal direction of the cover canvas 150), and the predetermined value. It is a range (10 ± 7 mm) between the upper limit value obtained by adding the values.

[Vision sensor]
As shown in FIG. 1, the covering processing unit 3 further includes a vision sensor 40 configured by a camera or the like. The vision sensor 40 photographs the tip portion 151 of the cover canvas 150 wound around the pair of pulleys 3a and 3b, and the tip portion position XP, which is the position of the tip portion 151 on the outer peripheral surface of the belt ring-shaped body 100. It functions as a position detector for detecting (see FIG. 8). Further, the vision sensor 40 serves as a distance detector for detecting a first distance L1 which is a distance along the outer peripheral surface of the belt ring-shaped body 100 from the tip position XP to a predetermined reference position SP (described later). Also works. Note that FIG. 8 is a diagram for explaining the adjustment of the winding length of the cover canvas 150.

The vision sensor 40 is installed in the molding apparatus 1 together with the illumination unit 45 (for example, an LED light source) via a mounting member (not shown). Specifically, the vision sensor 40 is positioned so that the imaging region A10 (see FIG. 9A) includes the predetermined reference position SP in the molding apparatus 1, that is, the position where the predetermined reference position SP can be imaged. It is installed in. Note that FIG. 9A is a diagram schematically showing a photographed image of the tip portion 151 of the cover canvas 150 during the covering process. The photographing area A10 is a rectangular area, and is set as an image processing area by the image processing unit 4b described later.

FIG. 5 is a schematic view for explaining the positional relationship between the vision sensor 40, the illumination unit 45, and the belt ring-shaped body 100 traveling between the pair of pulleys 3a and 3b, and these are viewed from above in the vertical direction. It is a figure. The vision sensor 40 is arranged at a position shifted to one side in the width direction of the belt ring-shaped body 100 with respect to a position facing the outer peripheral surface (back surface) of the belt ring-shaped body 100. That is, the vision sensor 40 is arranged at a position where not only the outer peripheral surface of the cover canvas 150 wound around the belt ring-shaped body 100 but also the side surface can be photographed. The illumination unit 45 is arranged at a position deviated from the position facing the outer peripheral surface of the belt ring-shaped body 100 on the other side (opposite side of the vision sensor 40) in the width direction of the belt ring-shaped body 100.

Further, as shown in FIG. 1, in the vertical direction, the vision sensor 40 is arranged at substantially the same position (height) as the predetermined reference position SP, while the illumination unit 45 is arranged at the predetermined reference position. It is preferably arranged below the SP. That is, the vision sensor 40 and the illumination unit 45 are arranged in a positional relationship such that a relatively dark shadow is formed on the stepped portion between the belt ring-shaped body 100 and the tip portion 151 of the cover canvas 150 in the image captured by the vision sensor 40. It is preferable that it is. As a result, when the tip portion 151 of the cover canvas 150 is photographed by the vision sensor 40, the bright and dark portions in the captured image can be sharpened, and the position detectability of the tip portion 151 of the cover canvas 150 can be improved. can. In other words, the tip position XP of the tip 151 of the cover canvas 150 can be detected more reliably.

The vision sensor 40 includes a memory (not shown), an interface circuit (not shown), and the like.

In the memory built in the vision sensor 40, a model image G10 (see FIG. 9B) of the tip portion 151 of the cover canvas 150 photographed in advance by the vision sensor 40 is stored. The model image G10 is stored as a identification image for identifying and detecting the tip portion 151 of the cover canvas 150 in the photographing region A10 of the captured image captured by the vision sensor 40 during the covering process.

Further, the memory built in the vision sensor 40 stores a program that defines various processes related to joining both ends of the cover canvas 150 in the longitudinal direction, in other words, forming a molding seam. For example, in the memory built in the vision sensor 40, a first distance, which is the distance between the tip position XP of the tip 151 of the cover canvas 150 and the predetermined reference position SP, based on the image captured by the vision sensor 40. A program for detecting L1 is stored.

[About the operation panel and control panel]
As shown in FIG. 1, the molding apparatus 1 has an operation panel 4 and a control panel 5.

FIG. 6A is a block diagram of the operation panel 4. As shown in FIG. 6A, the operation panel 4 houses the arithmetic control unit 4a. The arithmetic control unit 4a is configured by using, for example, a computer including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), or a PLC (Programmable Logic Controller).

The arithmetic control unit 4a has an image processing unit 4b and a setting information storage unit 4c. The image processing unit 4b is configured to be able to read and execute a predetermined program stored in the memory of the vision sensor 40. The setting information storage unit 4c is composed of a memory or the like. The setting information storage unit 4c is used to derive the estimated required rotation amount R10, which will be described later, and to calculate the distance (second distance L2) from the tip position XP of the tip 151 of the cover canvas 150 to the polymerization position LP. Contains the program to execute.

FIG. 6B is a block diagram of the control panel 5. As shown in FIG. 6B, the control panel 5 has a drive control unit 5a. The drive control unit 5a controls the drive operation of the traveling mechanism drive unit 3c and the like.

[How to join the cover canvas]
The joining method of the cover canvas 150 realized by the molding apparatus 1 having the above configuration will be described below with reference to FIGS. 7 to 10. FIG. 7 is a flowchart showing a method of joining the cover canvas 150 of the belt molded body 200. FIG. 8 is a schematic view for explaining the adjustment of the winding length of the cover canvas 150. FIG. 9 is a schematic view for explaining the amount of deviation (described later) of the tip position XP of the cover canvas 150 with respect to a predetermined reference position SP. FIG. 10 is a schematic view showing a state in which the front end portion 151 and the rear end portion 152 of the cover canvas 150 are overlapped with each other.

First, the outline of the joining method of the cover canvas 150 according to the present embodiment will be described.

Here, it is conceivable to stop the drive pulley 3a when the drive pulley 3a rotates a predetermined amount of rotation for moving the tip portion 151 of the cover canvas 150 from the pressing position PP to the polymerization position LP. However, as described above, the belt length of the belt ring-shaped body 100 varies. In particular, since the belt length of the wrapped V-belt is relatively longer than that of other types of transmission belts, the allowable range of the belt length with respect to the reference value is relatively large in the belt ring-shaped body 100 used in the molding process. The variation in belt length is relatively large.

Therefore, even if the drive pulley 3a rotates by the predetermined rotation amount and stops due to the variation in the belt length of the belt ring-shaped body 100, the tip portion 151 of the cover canvas 150 on the belt ring-shaped body 100 overlaps. It may have stopped at a position deviated from the position LP. For example, the tip portion 151 of the cover canvas 150 may have passed through the polymerization position LP, or may have reached only in front of the polymerization position LP. As described above, the tip portion 151 of the cover canvas 150, which should be stopped at the polymerization position LP in the calculation, stops at a position deviated from the polymerization position LP due to the variation in the belt length of the belt ring-shaped body 100. There may be. When the variation in the belt length of the belt ring-shaped body 100 is relatively large, the deviation of the tip portion 151 of the cover canvas 150 with respect to the polymerization position LP does not fall within the predetermined upper and lower limit ranges, and the cover canvas 150 has a predetermined deviation. There is a risk that the forming seam of the overlapping margin within the range of the upper and lower limits will not be formed.

In consideration of such a point, in the method of joining the cover canvas 150 according to the present embodiment, as will be described later, the cover canvas 150 is not at the polymerization position LP but at a predetermined reference position SP provided on the front side thereof. The rotation amount R10 of the drive pulley 3a that stops the tip portion 151 is derived. Then, when the drive pulley 3a rotates the rotation amount R10, the drive pulley 3a is stopped. After that, the amount of deviation of the position (tip position XP) of the tip portion 151 of the cover canvas 150 with respect to the reference position SP is detected, and the drive pulley 3a is controlled to rotate the rotation amount R20 in consideration of the detected deviation amount. NS.

As a result, even when the variation of the belt ring-shaped body 100 is relatively large, the tip portion 151 of the cover canvas 150 can be stopped more accurately at the polymerization position LP. As a result, regardless of the type of belt, the cover canvas 150 can form a molding seam of a stacking allowance within a predetermined upper and lower limit values.

Hereinafter, the method of joining the cover canvas 150 according to the present embodiment will be described in detail.

First, in step S11 (see FIG. 7), the estimated required rotation amount R10 (described below) is derived. The estimated required rotation amount R10 is estimated to be required to move the tip portion 151 of the cover canvas 150 from the predetermined pressing position PP by the pressing roll 31 to the predetermined reference position SP along the outer peripheral surface of the belt ring-shaped body 100. This is the amount of rotation of the drive pulley 3a. It should be noted that this step S11 constitutes the "derivation step" in the present invention.

The predetermined reference position SP is provided in order to more reliably adjust the winding length of the cover canvas 150 according to the variation in the length of the belt ring-shaped body 100. For example, as shown in FIG. 1, the predetermined reference position SP travels on the outer peripheral surface of the belt ring-shaped body 100 in a direction opposite to the circumferential direction with respect to the polymerization position LP, specifically, between the pair of pulleys 3a and 3b. It is provided in the latter half of the circumference of the inner belt ring-shaped body 100 (circulation starting from the pressing position PP). More specifically, as shown in FIG. 8, the reference position SP belts the reference distance L30 from the pressing position PP, which is considerably longer than the distance L10 along the canvas supply path 22 between the cutting position CP and the pressing position PP. It is provided at a position that goes back along the outer peripheral surface of the ring-shaped body 100 in a direction opposite to the circumferential direction.

Here, the shorter the distance along the outer peripheral surface of the belt ring-shaped body 100 from the reference position SP to the polymerization position LP, the shorter the adjustment section of the winding length of the cover canvas 150, and the better the adjustment accuracy (in other words, in other words). Adjustment error becomes smaller). However, when the distance from the reference position SP to the polymerization position LP is extremely short, for example, when the reference position SP is substantially the same as the polymerization position LP, it is caused by the variation in the belt length of the belt ring-shaped body 100. Therefore, there is a possibility that the tip position XP has reached the polymerization position LP when the drive pulley 3a rotates the estimated required rotation amount R10. In this case, the winding length of the cover canvas 150 cannot be adjusted.

Therefore, the reference position SP is more than the position (also referred to as the adjustment limit position) in which the adjustment limit distance described below is traced back from the pressing position PP along the outer peripheral surface of the belt ring-shaped body 100 in the direction opposite to the circumferential direction. It is preferable that it is provided in the direction opposite to the circumferential direction. The adjustment limit distance (not shown) is the maximum tolerance β of the belt length of the belt ring-shaped body 100 and the cover canvas with respect to the distance L20 along the outer peripheral surface of the belt ring-shaped body 100 from the pressing position PP to the overlapping position LP. It is the distance (= L20 + β + γ) including the maximum tolerance γ of the stacking allowance of 150.

The detailed operation of step S11 will be described. The arithmetic control unit 4a reads out a predetermined program stored in the setting information storage unit 4c, and has predetermined reference dimensions (specifically, outer peripheral length and thickness) and a drive pulley 3a for the belt ring-shaped body 100 to be supplied. The estimated required rotation amount R10 is derived based on the circumference of the above.

Specifically, first, the arithmetic control unit 4a acquires the outer peripheral length and the thickness of the supplied belt ring-shaped body 100, and inside the belt ring-shaped body 100 (specifically, the engagement surface with the drive pulley 3a). The circumference C10 is calculated. The outer peripheral length and thickness of the supplied belt ring-shaped body 100 are registered in advance in the setting information storage unit 4c, for example, in association with the belt type.

Then, based on the calculated inner peripheral length C10 and the outer peripheral length C20 of the drive pulley 3a (specifically, the engagement surface with the belt ring-shaped body 100), the tip portion 151 of the cover canvas 150 is the outer circumference of the belt ring-shaped body 100. The amount of rotation R0 (= C10 / C20) of the drive pulley 3a required to make one round on the surface is derived. Then, based on the rotation amount R0, the calculation control unit 4a is estimated to require the rotation amount of the drive pulley 3a to move the tip portion 151 of the cover canvas 150 from the pressing position PP to the reference position SP, that is, The estimated required rotation amount R10 is derived. Specifically, the rotation amount R0 is multiplied by the ratio of the outer peripheral length C100 of the belt ring-shaped body 100 to the peripheral length C90 from the pressing position PP to the reference position SP divided by the outer peripheral length C100. R0 × C90 / C100) is derived as the estimated required rotation amount R10.

In the next step S12, when the covering process is started and the drive pulley 3a rotates the estimated required rotation amount R10 from the time when the tip portion 151 passes through the pressing position PP (that is, the time when the covering process is started). , The rotation of the drive pulley 3a is temporarily stopped. Along with this, the running of the belt ring-shaped body 100 is temporarily stopped, and the movement of the cover canvas 150 on the outer peripheral surface of the belt ring-shaped body 100 is also temporarily stopped. In other words, the covering process is suspended. The step S12 constitutes the "pause step" in the present invention.

In the operation of step S12, the estimated required rotation amount R10 derived by the arithmetic control unit 4a is transmitted to the drive control unit 5a, and the drive control unit 5a performs the rotation operation of the drive pulley 3a based on the estimated required rotation amount R10. It is realized by controlling.

In the next steps S13 to S15, an operation of adjusting (in other words, correcting) the deviation of the tip position XP of the cover canvas 150 with respect to the reference position SP is executed.

First, in step S13, a first distance L1 which is a distance along the outer peripheral surface of the belt ring-shaped body 100 from the tip position XP of the tip 151 of the cover canvas 150 to the predetermined reference position SP by the vision sensor 40. Is detected. In addition, this step S13 constitutes the "detection step" in this invention.

Specifically, the vision sensor 40 generates image data (two-dimensional image data) including the tip portion 151 of the cover canvas 150. The image data generated by the vision sensor 40 is input to the image processing unit 4b in the arithmetic control unit 4a, and the image processing unit 4b reads a predetermined program in the memory built in the vision sensor 40. Then, based on the model image G10 (see FIG. 9B) of the cover canvas 150 photographed in advance, the tip portion 151 of the cover canvas 150 included in the imaging area A10 (see FIG. 9A) of the image data (see FIG. 9B). Specifically, the tip position XP) is specified and detected. More specifically, in the photographing region A10, the temporary stop position of the tip portion 151 of the cover canvas 150 on the outer peripheral surface of the belt ring-shaped body 100 is detected as the tip portion position XP of the tip portion 151. Here, in the photographing region A10, the direction parallel to the circumferential direction of the belt ring-shaped body 100 is the Y direction, and the direction perpendicular to the circumferential direction is the X direction.

Then, the image processing unit 4b generates Y coordinate data (for example, -5 mm) of the reference position SP with respect to the origin in the photographing region A10, and also generates Y coordinate data (for example, -15 mm) of the tip position XP with respect to the origin. Generate. Here, the bisector that bisects the photographing area A10 in the Y direction is used as the X coordinate axis in the photographing area A10. Then, the image processing unit 4b detects the first distance L1 (for example, 10 mm) along the outer peripheral surface of the belt ring-shaped body 100 from the tip position XP to the predetermined reference position SP based on each Y coordinate data. do. More specifically, the deviation amount α (for example, −10 mm) of the tip position XP with respect to the predetermined reference position SP is detected. Here, the orbital direction (downstream side) is set to "positive" and the direction opposite to the orbiting direction (upstream side) is set to "negative" with respect to the origin (Y = 0) in the Y direction in the photographing region A10.

Then, in step S14, based on the detected first distance L1 (more specifically, the deviation amount α), the outer peripheral surface of the belt ring-shaped body 100 from the tip position XP of the cover canvas 150 to the polymerization position LP. The second distance L2 (see FIG. 8), which is the distance along the line (distance in the circumferential direction), is calculated. More specifically, the distance between the pressing position PP and the reference position SP along the outer peripheral surface of the belt ring-shaped body 100 (distance in the circumferential direction) is the distance obtained by subtracting the distance L20 from the distance L30 and further reducing the deviation amount α. , The second distance is calculated as L2 (L2 = L30-L20-α). As described above, the distance L20 is the distance L10 from the cutting position CP to the pressing position PP on the canvas supply path 22 minus the predetermined stacking allowance K1.

For example, when the tip position XP of the tip 151 of the cover canvas 150 is in the circumferential direction with respect to the reference position SP (when the deviation amount α is a positive value), the distance is obtained by subtracting the distance L20 from the distance L30. The distance obtained by further subtracting the first distance L1 is calculated as the second distance L2 (L2 = L30-L20-L1). On the contrary, when the tip position XP of the tip 151 of the cover canvas 150 is in the direction opposite to the circumferential direction from the reference position SP (when the deviation amount α is a negative value), the distance L20 is subtracted from the distance L30. The distance obtained by adding the first distance L1 to the distance is calculated as the second distance L2 (L2 = L30-L20 + L1).

Then, in step S15, the covering process is restarted, and the drive pulley 3a is re-rotated when the rotation amount R20 corresponding to the second distance L2 is rotated from the time when the drive pulley 3a rotates the estimated required rotation amount R10. Control to stop is performed. The step S15 constitutes the "stop step" in the present invention.

Specifically, the arithmetic control unit 4a rotates the drive pulley 3a corresponding to the second distance L2 based on the outer peripheral length C20 of the drive pulley 3a (specifically, the engagement surface with the belt ring-shaped body 100). The quantity R20 is derived. Then, the derived rotation amount R20 is transmitted to the drive control unit 5a, and the drive control unit 5a controls the rotation operation of the drive pulley 3a based on the rotation amount R20. As a result, the covering process is restarted, and the drive pulley 3a stops again when the rotation amount R20 is rotated from the time when the drive pulley 3a rotates the estimated required rotation amount R10. As a result, the tip portion 151 of the cover canvas 150 stops at a position substantially the same as the polymerization position LP.

For example, in step S12, when the tip portion 151 of the cover canvas 150 is temporarily stopped at a position on the front side (upstream side in the circumferential direction) by the first distance L1 from the reference position SP, the first rotation amount is larger than the original rotation amount. The drive pulley 3a is controlled to rotate by the amount of rotation corresponding to the distance L1. As a result, the tip portion 151 of the cover canvas 150 stops at a position substantially the same as the polymerization position LP.

On the contrary, when the tip portion 151 of the cover canvas 150 is temporarily stopped on the downstream side in the circumferential direction by the first distance L1 from the reference position SP in step S12, it corresponds to the first distance L1 rather than the original rotation amount. The drive pulley 3a is controlled to rotate with a small amount of rotation. As a result, the tip portion 151 of the cover canvas 150 stops at a position substantially the same as the polymerization position LP.

In this way, the deviation of the tip portion 151 of the cover canvas 150 according to the variation of the belt ring-shaped body 100 is adjusted.

Then, in step S16, the cover canvas 150 is cut at a predetermined cutting position CP on the canvas supply path 22 by the cutting device 14, and both ends 151 and 152 of the cover canvas 150 are overlapped and joined (see FIG. 10). ).

Specifically, when the cover canvas 150 is cut by the cutting device 14 at a predetermined cutting position CP, the rear end portion 152 of the cover canvas 150 is formed. Then, the rear end portion 152 is overlapped and joined to the tip portion 151 of the cover canvas 150 stopped at the polymerization position LP. As described above, the polymerization position LP is the distance L20 (see FIG. 8) obtained by subtracting the predetermined stacking allowance K1 from the distance L10 on the canvas supply path 22 between the cutting position CP and the pressing position PP. It is provided at a position that goes back from the pressing position PP in the direction opposite to the circumferential direction along the outer peripheral surface. Therefore, when the rear end portion 152 of the cover canvas 150 formed by being cut at a predetermined cutting position CP is overlapped with the tip portion 151, the molding seam (the tip portion 151 and the rear end portion 152) of the cover canvas 150 is formed. The joint portion) is formed by a predetermined stacking allowance K1. Then, the drive pulley 3a rotates again, and the process of winding the rear end portion 152 of the cover canvas 150 around the belt ring-shaped body 100 is executed by the back roller 35, the side bending roll 34, and the like. As a result, the front end portion 151 and the rear end portion 152 are pressure-bonded to each other in a state where a molding seam of a predetermined stacking allowance K1 is formed, and are joined more firmly.

[effect]
As described above, in the method of joining the cover canvas 150 according to the present embodiment, when the drive pulley 3a rotates the estimated required rotation amount R10 from the time when the tip portion 151 of the cover canvas 150 passes through the pressing position PP. The position (tip position) XP of the tip portion 151 is detected. Further, the first distance L1 from the tip position XP to the predetermined reference position SP is detected. Then, the second distance L2 from the tip position XP to the polymerization position LP is calculated based on the first distance L1, and the drive pulley 3a rotates the rotation amount R20 corresponding to the second distance L2. And stop. After that, the front end portion 151 and the rear end portion 152 of the cover canvas 150 are overlapped and joined.

According to this configuration, the first position from the tip position XP of the cover canvas 150 when the drive pulley 3a rotates the estimated required rotation amount R10 to the predetermined reference position SP in the direction opposite to the circumferential direction from the polymerization position LP. Distance L1 is detected. Then, based on the first distance L1, the second distance L2 from the tip position XP to the polymerization position LP is calculated, and the drive pulley 3a determines the rotation amount R20 corresponding to the second distance L2. Rotate and stop. That is, even if the belt length of the belt ring-shaped body 100 varies, the winding length of the cover canvas 150 corresponds to the variation before the tip portion 151 of the cover canvas 150 reaches the overlapping position LP. Is adjusted. Therefore, for example, even when the covering treatment is applied to the belt ring-shaped body 100 (for example, the belt ring-shaped body of the wrapped V-belt) of a type in which the variation in the belt length is relatively large, the molding on the cover canvas 150 is performed. The seam can be formed with a stacking allowance within a predetermined upper and lower limit values. Therefore, regardless of the type of belt, it is possible to provide a method for joining the cover canvas 150, which can more reliably form a molding seam of a stacking allowance within a predetermined upper and lower limit range in the cover canvas 150. As a result, the yield can be secured regardless of the belt type of the transmission belt, and the productivity of the transmission belt can be improved.

Further, since such an operation is automatically performed by the control by the molding apparatus 1, the winding length of the cover canvas 150 is efficiently compared with the case where the worker manually adjusts the winding length, for example. Can be adjusted.

Further, in the method of joining the cover canvas 150 according to the present embodiment, the drive pulley 3a occurs when the drive pulley 3a rotates the estimated required rotation amount R10 from the time when the tip portion 151 of the cover canvas 150 passes through the predetermined pressing position PP. Control is executed to suspend the rotation of. Then, the temporary stop position of the tip portion 151 of the cover canvas 150 on the outer peripheral surface of the belt ring-shaped body 100 that has been temporarily stopped due to the temporary stop of the drive pulley 3a is detected as the tip portion position XP.

According to this configuration, the position of the tip portion 151 of the cover canvas 150 on the outer peripheral surface of the belt ring-shaped body 100 is a state in which the rotation of the drive pulley 3a is temporarily stopped, that is, a state in which the movement of the cover canvas 150 is suspended. Is detected by. Therefore, the position of the tip portion 151 of the cover canvas 150 can be detected more accurately.

Here, the vision sensor 40 is arranged in the vicinity of the polymerization position LP, and the rotation of the drive pulley 3a is stopped at the moment when the vision sensor 40 detects that the tip portion 151 of the cover canvas 150 has reached the polymerization position LP. , Is also possible. However, there is a limit to the image acquisition speed of the moving object, and after the vision sensor 40 detects that the tip portion 151 of the cover canvas 150 has reached the polymerization position LP, the drive pulley 3a actually rotates. There may be a slight time lag before the stop. As a result, the tip portion 151 of the cover canvas 150 may pass through the polymerization position LP.

On the other hand, in the joining method of the cover canvas 150 according to the present embodiment, the tip of the cover canvas 150 is set at a predetermined reference position SP in the direction opposite to the circumferential direction from the polymerization position LP instead of the polymerization position LP as a target stop position. The unit 151 is stopped. Therefore, the tip portion 151 does not pass through the polymerization position LP due to the time lag as described above, and the forming seam of the overlapping margin within the range of the predetermined upper and lower limit values can be more reliably formed in the cover canvas 150.

Further, in the present embodiment, the polymerization position LP sets the distance L20, which is obtained by subtracting the predetermined stacking allowance K1 from the distance L10 along the canvas supply path 22 between the cutting position CP and the pressing position PP, as the outer peripheral surface of the belt ring-shaped body 100. It is provided at a position upstream from the pressing position PP along the upper side in the direction opposite to the circumferential direction. That is, the distance (= L10) between the rear end portion 152 formed by being cut at the cutting position CP on the canvas supply path 22 and the pressing position PP along the canvas supply path 22 is from the pressing position PP to the polymerization position LP. The distance (= L20) along the outer peripheral surface of the belt ring-shaped body 100 is the distance obtained by adding the predetermined overlapping allowance K1. Therefore, the distance (= L10-) between the rear end portion 152 and the polymerization position LP is simply superposed on the tip portion 151 as it is by superimposing the rear end portion 152 formed by cutting at a predetermined cutting position CP on the canvas supply path 22 as it is. L20) becomes a predetermined overlapping allowance K1, and a molding seam that falls within the range of the predetermined upper and lower limit values is formed. Therefore, both ends 151 and 152 of the cover canvas 150 can be accurately overlapped with a predetermined overlapping allowance K1, and a forming seam of the overlapping allowance within a predetermined upper and lower limit values can be easily formed.

Further, in the method of joining the cover canvas 150 according to the present embodiment, the predetermined reference position SP is in the orbit of the belt ring-shaped body 100 traveling between the plurality of pulleys (in the present embodiment, the pair of pulleys 3a and 3b). It is provided in the latter half. Therefore, the winding length of the cover canvas 150 to be wound around the belt ring-shaped body 100 is adjusted as compared with the case where the predetermined reference position SP is provided in the first half portion of the circumference of the belt ring-shaped body 100 traveling between the plurality of pulleys. The section becomes shorter. Therefore, the accuracy of adjusting the winding length of the cover canvas 150 can be ensured.

Further, in the method of joining the cover canvas 150 according to the present embodiment, the estimated required rotation amount R10 is based on the predetermined peripheral length of the belt ring-shaped body 100 to be covered and the peripheral length of the drive pulley 3a. Is derived. Therefore, a more accurate estimated required rotation amount R10 can be derived according to the type of the belt ring-shaped body 100 to be covered.

Further, in the method of joining the cover canvas 150 according to the present embodiment, the tip portion 151 of the cover canvas 150 on the outer peripheral surface of the belt ring-shaped body 100 is detected based on the image data acquired by the vision sensor 40, and the first Distance L1 has been detected.

However, the present invention is not limited to this, and the tip portion 151 of the cover canvas 150 on the outer peripheral surface of the belt ring-shaped body 100 may be detected by the laser sensor.

Specifically, the laser is emitted toward a predetermined region on the outer peripheral surface of the belt ring-shaped body 100, and the reflected wave reflected in the predetermined region is received by the laser sensor. Then, the tip portion 151 of the cover canvas 150 is detected by calculating the distance (one-dimensional data) based on the time from the laser emission to the reception. In this way, the laser sensor may detect the tip portion 151 of the cover canvas 150 on the outer peripheral surface of the belt ring-shaped body 100.

However, the data acquired by the laser sensor is one-dimensional data (distance data to the object). In this case, in order to be able to detect the tip portion 151 of the cover canvas 150 when the thickness of the belt ring-shaped body 100 changes, a complicated arithmetic program for detecting the change point of the reference distance to the object is required. It takes.

Therefore, it is more preferable that the tip portion 151 of the cover canvas 150 is detected by using the vision sensor 40 as in the above embodiment. Specifically, the image data acquired by the vision sensor 40 is two-dimensional data. In this case, even if the thickness of the belt ring-shaped body 100 changes, that is, the reference distance to the object changes, the tip portion 151 of the cover canvas 150 can be detected without requiring a complicated calculation program. Therefore, even when the thickness changes depending on the belt type, the tip portion 151 of the cover canvas 150 on the outer peripheral surface of the belt ring-shaped body 100 can be easily detected.

[evaluation]
FIG. 11 is a diagram showing evaluations in each of the case of the embodiment of the present invention in which the cover canvas joining method according to the above embodiment is adopted and the case in which the cover canvas joining method according to the comparative example is adopted. .. In the embodiment of the present invention, the vision sensor 40 provided in the covering processing unit 3 of the molding apparatus 1 of the belt molded body for carrying out the method of joining the cover canvas according to the above embodiment is manufactured by Mitsubishi Electric Corporation. The vision sensor of model number VS80M-200E was used. Further, as a comparative example, an embodiment in which the adjustment process of the winding length of the cover canvas is not executed is illustrated.

Here, the evaluation was performed using the following belt ring-shaped body. Specifically, the belt length is at the upper limit level that can be molded by the molding device of the belt molded body, and the reference value of the belt length exceeds the allowable range with respect to the reference value of the stacking allowance of the cover canvas. A belt ring-shaped body having a large permissible range was used. The reference value of the belt length (outer peripheral length) of the belt ring-shaped body is 105 inches (2667 mm). Further, the allowable range with respect to the reference value is ± 10 mm, that is, the maximum tolerance β is 10 mm with respect to the reference value of 2667 mm. The variation (measured value) with respect to the reference value is ± 9.0 mm, which is almost a normal distribution. It should be noted that this variation is a measurement result measured by an inspector, assuming that the number of objects is 200. The thickness t is 8.2 mm and the width w is about 13 mm. The permissible range of the thickness t with respect to the reference value is ± 0.2 mm.

Then, 100 belt ring-shaped bodies and a cover canvas (two-layer cover canvas composed of a lower cover and an upper cover) were supplied to the molding apparatus to prepare 100 belt molded bodies.

The evaluation method (measurement method) is as follows.

As a method for measuring the outer peripheral length of the belt ring shape, an inspector uses a gold tape measure (measurement unit 1 mm) for each of the 100 belt ring shapes (belt ring shapes of the same production lot) supplied for evaluation. The outer circumference length of the body was measured.

Further, the upper and lower limit range (reference range) of the overlapping allowance of the molding seam was set to 10 mm ± 7 mm, and the number of inspection points was set to two places, the back side and the bottom side, with respect to one molding seam in the belt molded body. In addition, a two-layer cover canvas composed of a lower cover and an upper cover was inspected. That is, the total number of inspection points is 400 (= the number of molding seams 100 × 2 layers of cover canvas × 2 inspection points). As a method for inspecting the molding seam, the inspector measured the overlap margin of the molding seam with a metal scale (measurement unit 0.5 mm) after the covering treatment of each of the lower cover and the upper cover was completed. After the covering treatment of the lower cover, the inspection was performed with the molding seam moved between the pair of pulleys.

The evaluation criteria are as follows.
A1: The overlap margin (actual value) of the molding seam is all within the predetermined upper and lower limit range (the part outside the upper and lower limit range is "0") with respect to the total number of inspection points.
A2: The average value of the stacking allowance is within the range of 10 mm (reference value) ± 3 mm.
A3: The fluctuation width R value of the stacking allowance is 7 mm (half of the allowable width of 14 mm) or less.
When all of the three criteria A1 to A3 of the above are satisfied, it is evaluated that it is possible to provide a joining method of the cover canvas that can more reliably form a molding seam of a predetermined stacking allowance in the cover canvas (determination "○"). .. Specifically, when all of the above three criteria A1 to A3 are satisfied, if the belt ring is a formable type, the belt ring exceeds the permissible range for the reference value of the stacking allowance of the cover canvas. Even if the belt lengths vary, it can be evaluated that the molding seams of a predetermined stacking allowance can be formed more reliably regardless of the belt type (particularly the belt length).

On the contrary, when at least one of the above three criteria A1 to A3 is not satisfied, it cannot be said that the molding seam of the predetermined stacking allowance can be surely formed in the cover canvas (determination "x").

Under such evaluation criteria, the evaluation results of the above-described embodiment and the aspect according to the comparative example are as follows.

First, in the method of joining the cover canvas according to the present embodiment, as shown in FIG. 11, the number of places where the overlapping allowance (actual value) of the molding seam is outside the predetermined upper and lower limit range is the total number of inspection places. It was "0 places" with respect to "400 places". The average value of the stacking allowance was 10.2 mm, which was within the range of the reference value of 10 ± 3 mm. The fluctuation width R value of the stacking allowance was 3.0 mm (maximum value was 11.5 mm, minimum value was 8.5 mm), and was 7 mm or less. That is, in the method of joining the cover canvas according to the present embodiment, all of the above three criteria A1 to A3 are satisfied. As a result, regarding the method of joining the cover canvas according to the present embodiment, it was evaluated that "a molding seam of a predetermined stacking allowance can be more reliably formed in the cover canvas" ("○" in FIG. 11).

On the other hand, in the cover canvas joining method according to the comparative example, as shown in FIG. 11, the number of places where the overlapping allowance (actual value) of the molding seam is outside the predetermined upper and lower limit range is the total inspection place. The number was "88" as opposed to "400". The fluctuation width R value of the stacking allowance was 18.0 mm (maximum value was 19.5 mm, minimum value was 1.5 mm), which was larger than 7 mm. The average value of the stacking allowance was 10.4 mm, which was within the range of the reference value of 10 ± 3 mm. That is, in the method of joining the cover canvas according to the comparative example, the two criteria A1 and A3 out of the above three criteria A1 to A3 are not satisfied, and "the molding seam of the predetermined stacking allowance is surely secured in the cover canvas. It cannot be said that it can be formed in "(" x "in FIG. 11).

From the above evaluation results, it can be seen that the cover canvas joining method according to the above embodiment can more reliably form a molding seam within a predetermined upper and lower limit range (more preferably, a predetermined stacking allowance) in the cover canvas. ..

[Modification example]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, the following modification may be carried out.

(1) In the above-described embodiment, the rotation of the drive pulley 3a is temporarily stopped when the drive pulley 3a rotates the estimated required rotation amount R10 from the time when the tip portion 151 of the cover canvas 150 passes the pressing position PP. (Step S12 in FIG. 7), but the present invention is not limited to this. For example, the rotation speed of the drive pulley 3a is reduced at the time when the drive pulley 3a rotates the estimated required rotation amount R10 from the time when the tip portion 151 of the cover canvas 150 passes through the pressing position PP, or at the time immediately before that. You may.

The present invention relates to a covering process for covering a belt ring-shaped body with a cover canvas, and a wide range of methods for joining the cover canvas for superimposing and joining both ends of the cover canvas in the longitudinal direction within a predetermined upper and lower limit values. Applicable.

1 Molding device 2 Canvas supply mechanism 3 Covering processing unit 3a Drive pulley (upper pulley)
3b Lower pulley 4 Operation panel 4a Calculation control unit 5 Control panel 13 Canvas gripping unit 14 Cutting device 22 Canvas supply path 100 Belt ring 106 Lower cover (cover canvas)
107 Top cover (cover canvas)
150 Cover canvas 151 Front end of cover canvas 152 Rear end of cover canvas 200 Belt molded body

Claims (6)

In the covering process of covering the cover canvas with the belt ring-shaped body traveling between the plurality of pulleys including the drive pulley, the front end portion and the rear end portion in the longitudinal direction of the cover canvas are overlapped within a predetermined upper and lower limit values. It is a method of joining cover canvas for joining together.
The outer circumference of the belt ring from a predetermined pressing position where the cover canvas is pressed against the belt ring running between the plurality of pulleys and the contact of the cover canvas with the belt ring is started. It is presumed that it is necessary to move the tip portion to a predetermined reference position in the direction opposite to the circumferential direction from the stacking position where the tip portion and the rear end portion can be overlapped with a predetermined stacking allowance on the surface. The derivation step for deriving the estimated required rotation amount, which is the rotation amount of the drive pulley,
Detects the tip position, which is the position of the tip on the outer peripheral surface of the belt ring-shaped body, when the drive pulley rotates the estimated required rotation amount from the time when the tip passes the predetermined pressing position. In addition, a detection step of detecting a first distance, which is a distance along the outer peripheral surface of the belt ring from the tip position to the predetermined reference position,
A calculation step of calculating a second distance, which is a distance along the outer peripheral surface of the belt ring from the tip position to the polymerization position, based on the first distance.
A stop step of stopping the drive pulley when the drive pulley rotates the rotation amount corresponding to the second distance from the time when the estimated required rotation amount is rotated.
The cover canvas is cut at a predetermined cutting position on the canvas supply path of the cover canvas, and the front end portion and the rear end portion formed by cutting the cover canvas are set based on the predetermined cutting position. The joining step of superimposing and joining at the said polymerization position,
A method of joining a cover canvas, which comprises having. In the method for joining the cover canvas according to claim 1,
Prior to the detection step, a pause step of suspending the rotation of the drive pulley from the time when the tip portion passes the predetermined pressing position to the time when the drive pulley rotates the estimated required rotation amount is further performed. Have and
The detection step is characterized in that the temporary stop position of the tip portion on the outer peripheral surface of the belt ring-shaped body that has been temporarily stopped due to the temporary stop of the drive pulley is detected as the tip portion position. How to join the cover canvas. In the method of joining the cover canvas according to claim 1 or 2.
The polymerization position is the distance between the predetermined cutting position and the predetermined pressing position along the canvas supply path minus the predetermined stacking allowance along the outer peripheral surface of the belt ring-shaped body. A method of joining a cover canvas, characterized in that the cover canvas is provided at a position that goes back from a predetermined pressing position in a direction opposite to the circumferential direction. The method for joining the cover canvas according to any one of claims 1 to 3.
In the detection step, the tip portion on the outer peripheral surface of the belt ring-shaped body is detected based on the image data acquired by the vision sensor including the predetermined reference position in the photographing region, and the first distance is set. A method of joining a cover canvas, characterized in that it is detected. The method for joining the cover canvas according to any one of claims 1 to 4.
The cover is characterized in that the predetermined reference position is the orbit of the belt ring-shaped body traveling between the plurality of pulleys and is provided in the latter half of the orbit starting from the predetermined pressing position. How to join the canvas. The method for joining the cover canvas according to any one of claims 1 to 5.
In the derivation step, a method of joining a cover canvas, characterized in that the estimated required rotation amount is derived based on a predetermined peripheral length of the belt ring-shaped body and the peripheral length of the drive pulley.

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