Abstract:
The present invention discloses a rubber band machine. The length of a rubber band to be conveyed may be set by controlling the angle of rotation of a first motor. The rubber band input by a first feeding drive wheel is stored between the first feeding drive wheel and a second feeding drive wheel so that the second feeding drive wheel coordinates with a looping device to continue to output the rubber band. During feeding, the rubber band machine can perform joint examination and ironing to the rubber band, and automatically cut the rubber band off at the discharge port of the second feeding drive wheel via a cutting device. The looping device grips the rubber band via a third gripper and moves rotationally to convey two ends of the rubber band to a first gripper and a second gripper, respectively. After the first gripper and the second gripper have gripped the two ends of the rubber band, the rubber band forms a rubber ring by rotational motion of the first gripper and the second gripper, and the two jointed ends of the rubber ring are fixed on a bracket for subsequent sewing and fixation. The looping device has the advantages of simple structure and automatic control, and the looping speed of rubber bands is thus greatly improved.

Description:
This is a U.S. national stage application of PCT Application No. PCT/CN2014/075542 under 35 U.S.C. 371, filed Apr. 17, 2014 in Chinese, claiming the priority benefit of Chinese Application No. 2013102741210, filed Jul. 2, 2013, which is hereby incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to a rubber band machine for processing a rubber band into a rubber ring. 
     BACKGROUND OF THE INVENTION 
     During the production of rubber rings, the common manufacturing process is as follows: taking bundles or rolls of rubber bands as raw materials, cutting them into segments and sewing them into rings. During the production, those operations are accomplished manually or by a plurality of single machines with different functions. Chinese Utility Model Patent No. 201020269752.5 titled Rubber Band Feeding Device for Automatic Rubber band Machines, Chinese Utility Model Patent No. 201020269792.X titled Rubber Band Length Control Device for Automatic Rubber Band Machines, Chinese Utility Model Patent No. 201020269783.0 titled Cutting Device for Automatic Rubber Band Machines, Chinese Utility Model Patent No. 201020269797.2 titled Rubber Band Looping Device for Automatic Rubber Band Machines, and Chinese Utility Model Patent No. 201020269802.X titled Pulling Device for Automatic Rubber Band Machines disclosed a full-automatic rubber band processing equipment integrating sorting, feeding, length controlling, cutting, splicing and sewing in one equipment. Such a full-automatic rubber band processing equipment can automatically accomplish the whole production procedure of processing rubber bands into rubber rings. However, the processability and production assembly of such a full-automatic rubber band processing equipment can be further improved. 
     SUMMARY OF THE INVENTION 
     In view of the status of the prior art, the present invention provides a rubber band machine with higher processing efficiency. 
     To solve the above technical solution, the present invention employs the following technical solution: a rubber band machine is provided, comprising a feeding device, a cutting device and a looping device, characterized in that the feeding device comprises a first rack and a second rack arranged at intervals, the first rack being provided with a first feeding drive wheel driven by a first motor, the second rack being provided with a second feeding drive wheel driven by a second motor; the looping device comprises a first gripper capable of rotating around a first axis, a second gripper capable of rotating around a second axis, a bracket disposed between the first gripper and the second gripper, and a third gripper capable of rotating around a third axis; the first feeding drive wheel rotates and inputs a predetermined length of rubber band between the first feeding drive wheel and the second feeding drive wheel, the third gripper grips one end of the rubber band at the discharge port of the second feeding drive wheel and rotates around the third axis under the auxiliary feeding of the second feeding drive wheel to allow a predetermined length of the rubber band to pass through the first gripper and the second gripper, and then the rubber band at the discharge port of the second feeding drive wheel is cut by the cutting device; after gripping two ends of the cut rubber band, the first gripper and the second gripper rotate around the first axis and the second axis, respectively, to fix the two ends of the rubber band onto the bracket. 
     To optimize the above technical solution, the present invention further comprises the following improved technical solution. 
     The rubber band input by the first feeding drive wheel is suspended between the first feeding drive wheel and the second feeding drive wheel; a stock sensor for detecting the suspension state of the rubber band is disposed below the first feeding drive wheel; the second feeding drive wheel conveys the suspended rubber band when the third gripper moves rotationally; and, the first motor controls the first feeding drive wheel to convey a next predetermined length of the rubber band after the stock sensor detects that the rubber band in the suspended state is straightened. 
     The first rack is provided with a first feeding driven wheel fitted with the first feeding drive wheel; the second rack is provided with a second feeding driven wheel fitted with the second feeding drive wheel; a rubber band conveying passage is disposed above the first feeding drive wheel, and a heating plate for ironing the rubber band and a heating cylinder for controlling the heating plate to move close to or move away from the rubber band conveying passage are provided on one side of the rubber band conveying passage. 
     A joint sensor for detecting the thickness of the rubber band is provided on one side of the rubber band conveying passage, and the joint sensor controls the first motor to stop working when detecting that the thickness of the rubber band becomes larger. 
     The cutting device comprises a moving cutter and a stationary cutter disposed at the discharge port of the second feeding drive wheel, the moving cutter being connected to the drive rod of a cutting cylinder. 
     The looping device comprises a third rack on which a slidable base is disposed, the base being connected to the drive rod of a sliding cylinder; and, the first gripper, the second gripper and the bracket are all disposed on the base. 
     The base is provided with a first rotating cylinder for driving the first gripper to rotate around the first axis and a second rotating cylinder for driving the second gripper to rotate around the second axis at intervals, and the distance from the first axis to the second axis is adjustable. 
     The third rack is provided with a third drive shaft capable of rotating, and one end of the third drive shaft is connected to the third gripper via a third connecting arm while the other end thereof is linked to a third rotating cylinder on the third rack. 
     A second guide rail, on which the bracket is slidably disposed, is disposed on the base, and a tension spring is disposed between the bracket and the base. 
     Compared with the prior art, the rubber band machine provided by the present invention can allow the first feeding drive wheel to convey a predetermined length of rubber band by controlling the angle of rotation of the first motor, and each segment of the rubber band input by the first feeding drive wheel is stored between the first feeding drive wheel and the second feeding drive wheel so that the second feeding drive wheel coordinates with a looping device to output the rubber band continuously. During feeding, the rubber band machine may perform joint examination and ironing to the rubber band, and automatically cut the rubber band off at the discharge port of the second feeding drive wheel via the cutting device. The looping device grips the rubber band via the third gripper and moves rotationally to convey two ends of the rubber band to the first gripper and the second gripper, respectively. After the first gripper and the second gripper have gripped the two ends of the rubber band, the rubber band forms a rubber ring by rotational motion of the first gripper and the second gripper, and the two jointed ends of the rubber ring are fixed on the bracket for subsequent sewing and fixation. The looping device has the advantages of simple structure and automatic control, and the looping speed of rubber bands is thus greatly improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a stereoscopic/three dimensional structure diagram according to an embodiment of the present invention; 
         FIG. 2  is a stereoscopic structure diagram of a feeding part of  FIG. 1 ; 
         FIG. 3  is an exploded assembly view of a first rack part of  FIG. 2 ; 
         FIG. 4  is an exploded assembly view of a second rack part of  FIG. 2 ; 
         FIG. 5  is a stereoscopic structure diagram of a looping device of  FIG. 1 ; 
         FIG. 6  is a rear stereoscopic structure diagram of  FIG. 5 ; and 
         FIG. 7  is an exploded assembly view of  FIG. 6 . 
     
    
    
     In the drawings, the meanings of the reference numerals are as follows:  1 —First rack;  11 —Heating plate;  11   a —Heating guide rail;  11   b —Electrical heating rod;  12 —Heating cylinder;  12 —Stock sensor;  14 —Third motor;  15 —Material sorting roller;  16 —Backup plate;  17 —Adjusting and limiting stopper;  18 —Joint sensor;  18   a —Sensing flap;  2 —Second rack;  21 —First mounting substrate;  22 —Second mounting substrate;  23 —Third mounting substrate;  24 —Feeding carrier;  25 —Driven wheel shaft;  26 —Adjusting block;  3 —First feeding drive wheel;  31 —First motor;  32 —First feeding driven wheel;  33 —First driven wheel mounting support;  34 —First spring;  4 —Second feeding drive wheel;  4   a —Rotary drive shaft;  41 —Second motor;  41   a —First synchronous wheel;  41   b —Second synchronous wheel;  41   c —First synchronous belt;  42 —Second feeding driven wheel;  43 —Second driven wheel mounting support;  44 —Second spring;  5 —Third rack;  5   a —Bedplate;  5   b —Support frame;  51 —Sliding cylinder;  52 —Third drive shaft;  52   a —Third synchronous wheel;  53 —Third connecting arm;  54 —Third rotating cylinder;  54   a —Fourth synchronous wheel;  54   b —Second synchronous belt;  55 —First guide rail;  57 —Third gripper;  6 —Base;  61 —Bracket;  61   a —Material support frame;  62 —Second gripper;  63   a —Second cylinder mounting plate;  63   b —Second drive shaft;  63   c —Second connecting arm;  63   d —Second rotating cylinder;  64 —Second guide rail;  65 —Tension spring;  66 —Support plates;  67 —Connecting plate;  67   a —Carrier mounting frame;  67   b —Carrier;  68 —Air pipe mounting support;  68   a —Air blowpipe;  68   b —Mounting shaft;  68   c —Positioning backup plate;  7 —Moving cutter;  71 —Stationary cutter;  72 —Cutting cylinder;  73 —Moving cutter mounting frame;  74 —Moving cutter arm;  8 —Gripping cylinder;  81 —Fixed arm; and,  82 —Moving arm. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention will be further described as below in details with reference to the accompanying drawings. 
     As shown in  FIG. 1 , the rubber band machine provided by the present invention comprises a feeding device, a cutting device and a looping device. The feeding device comprises a first rack  1  and a second rack  2  arranged at intervals. The first rack  1  is provided with a first feeding drive wheel  3  driven by a first motor  31 . The second rack  2  is provided with a second feeding drive wheel  4  driven by a second motor  41 . The looping device comprises a first gripper  62  capable of rotating around a first axis, a second gripper  63  capable of rotating around a second axis, a bracket  61  disposed between the first gripper  62  and the second gripper  63 , and a third gripper  57  capable of rotating around a third axis. The first feeding drive wheel  3  rotates and inputs a predetermined length of rubber band between the first feeding drive wheel  3  and the second feeding drive wheel  4 . The third gripper  57  grips one end of the rubber band at the discharge port of the second feeding drive wheel  4  and rotates around the third axis under the auxiliary feeding of the second feeding drive wheel  4  to allow a predetermined length of the rubber band to pass through the first gripper  62  and the second gripper  63 , and then the rubber band at the discharge port of the second feeding drive wheel  4  is cut by the cutting device. After gripping two ends of the cut rubber band, the first gripper  62  and the second gripper  63  rotate around the first axis and the second axis, respectively, to fix the two ends of the rubber band onto the bracket  61 . 
     As shown  FIG. 2 , the feeding device of the rubber band machine comprises a first rack  1  and a second rack  2  spaced apart from each other. The first rack  1  is provided with a first feeding drive wheel  3  driven by a first motor  31 . The second rack  2  is provided with a second feeding drive wheel  4  driven by a second motor  41 . The first feeding drive wheel  3  inputs a predetermined length of rubber band under the control of the first motor  31 , and the rubber band is suspended between the first feeding drive wheel  3  and the second feeding drive wheel  4 . A stock sensor  13  for detecting the suspension state of the rubber band is disposed below the first feeding drive wheel  3 . The second feeding drive wheel  4  conveys the suspended rubber band under the control of the second motor  41 . The first motor  31  controls the first feeding drive wheel  3  to convey a next predetermined length of the rubber band after the stock sensor  13  detects that the rubber band in the suspended state is straightened. 
       FIG. 3  shows an exploded assembly view of the first rack  1  part. A rubber band conveying passage is disposed above the first feeding drive wheel  3 . A material sorting roller  15  driven by the third motor  14  is disposed above the first feeding drive wheel  3 . The rubber band conveying passage is vertically disposed between the material sorting roller  15  and the first feeding drive wheel  3 . 
     In this embodiment, the first rack  1  is fixedly connected with a backup plate  16 , and the rubber band conveying passage is vertically disposed on the backup plate  16 . An adjusting and limiting stopper  17  for adjusting the width of the rubber band conveying passage is disposed on the backup plate  16 . 
     A heating plate  11  for ironing the rubber band and a heating cylinder  12  for controlling the heating plate  11  to move close to or move away from the rubber band conveying passage is disposed on one side of the rubber band conveying passage. 
     When the first motor  31  works, the heating cylinder  21  controls the heating plate  11  to move close to the rubber band inside the rubber band conveying passage, and irons the rubber band being conveyed. When the first motor  31  stops working, the heating cylinder  12  controls the heating plate  11  to move away from the rubber band conveying passage. 
     The first rack  1  is provided with a heating guide rail  11   a  on which the heating plate  11  is slidably disposed. An electrical heating rod  11   b  is provided in the heating plate  11 . 
     A joint sensor  18  for detecting the thickness of the rubber band is disposed on one side of the rubber band conveying passage. The rubber band may have joints which cannot be allowed during the manufacturing of rubber rings. As the thickness of the rubber band at a joint becomes larger, the first motor  31  and the second motor  41  are controlled to stop conveying the rubber band when the joint sensor  18  detects the thickness of the rubber band becomes larger, so that it is convenient for workers to remove the joints of the rubber band. 
     The joint sensor  18  is provided with a freely suspended sensing flap  18   a . One bent portion of the sensing flap  18   a  is fitted with the vertical rubber band in the rubber band conveying passage, while the other bent portion of the sensing flap  18   a  is positioned in the vicinity of a contact point of the joint sensor  18 . When there is a joint on the rubber band, the sensing flap  18   a  comes into contact with the contact point of the joint sensor  18 , so that the joint sensor  18  detects the joint of the rubber band and timely controls the feeding device to stop working. 
     The first feeding drive wheel  3  is provided with a first feeding driven wheel  32  clung thereto due to elasticity. A first driven wheel mounting support  33  capable of rotating is disposed on the other side of the backup plate  16 . The first feeding drive wheel  3  is rotatably disposed on the first driven wheel mounting support  33 . The backup plate  16  is provided with a first spring  34  fitted with the first driven wheel mounting support  33 . One end of the first spring is fitted with a mounting rod on the backup plate  16 , while the other end thereof is fitted with a connecting member on the first driven wheel mounting support  33 . The first driven wheel mounting support  33  enables in the aid of the elasticity of the first spring  34  the first feeding driven wheel  32  to cling to the first feeding drive wheel  3 . 
       FIG. 4  shows an exploded assembly view of the second rack  2  part. The second rack  2  comprises a first mounting substrate  21  and a second mounting substrate  22  which are provided in parallel, and a third mounting substrate  23  vertically connected to the first mounting substrate  21  and the second mounting substrate  22 , respectively. 
     A rubber band conveying passage is provided between the first mounting substrate  21  and the second mounting substrate  22 . A feeding carrier  24  is fixed between the first mounting substrate  21  and the second mounting substrate  22 . A driven wheel shaft  25  is disposed above the feeding carrier  24 . The rubber band conveying passage is positioned between the feeding carrier  24  and the driven wheel shaft  25 . 
     After conveyed by the first feeding drive wheel  3 , the rubber band passes between the driven wheel shaft  25  and the feeding carrier  24  and is then conveyed by the second feeding drive wheel  4 . An adjusting block  26  capable of adjusting the width of the rubber band conveying passage is disposed on the driven wheel shaft  25  in order to adapt for conveying rubber bands in different width. 
     The second feeding drive wheel  4  is rotatably disposed between the first mounting substrate  21  and the second mounting substrate  22 . The second motor  41  and the second feeding drive wheel  4  are positioned on two sides of the first mounting substrate  21 , respectively. A power output shaft of the second motor  41  is connected with a first synchronous wheel  41   a . The rotary drive shaft  4   a  of the second feeding drive wheel  4  passes through the first mounting substrate  21 , and the outgoing end thereof is connected with a second synchronous wheel  41   b . A first synchronous belt  41   c  is disposed between the first synchronous wheel  41   a  and the second synchronous wheel  41   b . The second motor  41  drives the second feeding drive wheel  4  to move via the first synchronous wheel  41   a , the first synchronous belt  41   c  and the second synchronous wheel  41   b.    
     A moving cutter  7  and a stationary cutter  71  for cutting the rubber band off are disposed at the discharge port of the second feeding drive wheel  4 . The moving cutter  7  cuts off the rubber band at the discharge port via a cutting cylinder  72  after the second feeding drive wheel  4  completes the feeding of the rubber band. 
     In this embodiment, a moving cutter mounting frame  73  is fixedly connected to one side of the third mounting substrate  23  close to the first feeding drive wheel  3 . The moving cutter mounting frame  73  is provided with a moving cutter arm  74  capable of rotating. The moving cutter  7  is fixed on the moving cutter arm  74  and positioned below the second feeding drive wheel  4 . 
     The cutting cylinder  72  for driving the moving cutter  7  to rotate is movably mounted on the first mounting substrate  21 , and positioned below the second motor  41 . The drive rod of the cutting cylinder  72  drives the moving cutter arm  74  to rotate via a connecting rod. 
     The second feeding drive wheel  4  is provided with a second feeding driven wheel  42  clung thereto due to elasticity. A second driven wheel mounting support  43  capable of rotating is disposed on the outer side of the third mounting substrate  23 , and the second feeding driven wheel  42  is rotatably disposed on the second driven wheel mounting support  43 . The third mounting substrate  23  is provided with a second spring  44  fitted with the second driven wheel mounting support  43 . One end of the second spring  44  is fitted with a mounting rod on the third mounting substrate  23 , while the other end thereof enables due to the elasticity the second feeding driven wheel  42  on the second driven wheel mounting support  43  to compress the second feeding drive wheel  4 . 
     When in work, the rubber band passes between the first feeding drive wheel  3  and the first feeding driven wheel  32  at first, and then passes between the second feeding drive wheel  4  and the second feeding driven wheel  42 . A stock sensor  13  is fixedly disposed below the first feeding drive wheel  3 . The length of the rubber band conveyed by the first feeding drive wheel  3  may be controlled by controlling the rotating revolutions of the first motor  31 . After the first feeding drive wheel  3  conveys a predetermined length of rubber band, the rubber band is suspended between the first feeding drive wheel  3  and the second feeding drive wheel  4 , and the suspended rubber band coordinates with the stock sensor  13  to enable the stock sensor  13  to detect that the rubber band is in the suspended state. 
     When the third gripper  57  grips and rotates the rubber band, the second motor  41  controls the second feeding drive wheel  4  to feed quickly and output the rubber band for subsequent looping operation. The rubber band suspended between the first feeding drive wheel  3  and the second feeding drive wheel  4  is straightened gradually. The rubber band after straightened is separated from the stock sensor  13 , and the stock sensor  13  controls the first motor  31  to make the first feeding drive wheel  3  convey a next segment of the rubber band after detecting that the rubber band is separated from it. 
     As shown in  FIG. 5 , the looping device of the rubber band machine comprises a third rack  5  and a base  6  disposed on the third rack  5 . In this embodiment, the third rack  5  is a composite member consisting of a bedplate  5   a  and a support frame  5   b . The third rack  5  is positioned below the second rack  2 , so that it is convenient for the third gripper  57  to grip the rubber band at the discharge port of the second feeding drive wheel  4 . 
     A first guide rail  55  is provided on the bedplate  5   a  of the third rack  5 , while the base  6  is slidably disposed on the first guide rail  55 . A sliding cylinder  51  for driving the base  6  to slide is disposed on the third rack  5 . By controlling the base  6  to move via the sliding cylinder  51 , the looped rubber band may be conveyed to a sewing position for sewing. 
     The first gripper  62  and the second gripper  63  for gripping the rubber band are disposed on the base  6  at intervals, and may rotate around the first axis and the second axis, respectively. In this embodiment, a first cylinder mounting plate  62   a  and a second cylinder mounting plate  63   a  are fixed on the base  6  at intervals, with a first rotating cylinder  62   d  and a second rotating cylinder  63   d  being mounted on the first cylinder mounting plate  62   a  and the second cylinder mounting plate  63   a , respectively. 
     The first rotating cylinder  62   d  is provided with a first drive shaft  62   b  connected to the first gripper  62  via a first connecting arm  62   c . The first axis is coincided with the axis of the first drive shaft  62   b . The second rotating cylinder  63   d  is provided with a second drive shaft  63   b  connected to the second gripper  63  via a second connecting arm  63   c . The second axis is coincided with the axis of the second drive shaft  63   b.    
     The first rotating cylinder  62   d  may drive the first gripper  62  to rotate around the first drive shaft  62   b  where the first axis is located. The second rotating cylinder  63   d  may drive the second gripper  63  to rotate around the second drive shaft  63   b  where the second axis is located. 
     The first cylinder mounting plate  62   a  and the second cylinder mounting plate  63   a  are formed with adjustable mounting grooves, respectively. The positions of the first cylinder mounting plate  62   a  and the second cylinder mounting plate  63   a  on the base  6  may be adjusted by the adjustable mounting grooves, thereby adjusting the distance from the first axis to the second axis. 
     A bracket  61  is disposed between the first gripper  62  and the second gripper  63 , and fixed on the base  6  via a material support frame  61   a.    
     The material support frame  61   a  has an extended end which is positioned between the first gripper  62  and the second gripper  63 . The bracket  61  is fixed on the end of the material support frame  61   a . The first rotating cylinder  62   d  and the second rotating cylinder  63   d  may drive the corresponding first gripper  62  and second gripper  63  to rotate, respectively, to fix the gripped rubber band onto the bracket  61 . 
     In this embodiment, the extended end of the material support frame  61   a  is protruded relatively. The bracket  61  will run into a sewing device in the process of moving the base  6  to the sewing position. Therefore, during the movement of the base  6 , the movement stroke of the bracket  61  is less than that of the base  6 . To make the movement stroke of the bracket  61  less than that of the base  6 , a second guide rail  64  is disposed on the base  6 . The second guide rail  64  is positioned between the first cylinder mounting plate  62   a  and the second cylinder mounting plate  63   a . The material support frame  61   a  is slidably disposed on the second guide rail  64 , and a tension spring  65  is provided between the material support frame  61   a  and the base  6 . In this way, the bracket  61  may stop moving when running into the sewing device, and the base  6  continues to move and convey the looped rubber band to the sewing position. 
     The base  6  is connected to a connecting plate  67  via two support plates  66 . An air pipe mounting support  68  is fixed at the upper part of the connecting plate  67 . The air pipe mounting support  68  is provided with two air blowpipes  68   a  connected to an air pump. The outlets of the air blowpipes  68   a  are positioned above the bracket  61 . A mounting shaft  68   b  is fixed between the two air blowpipes  68   a , and fixedly provided thereon with a positioning backup plate  68   c  for positioning the rubber band. A carrier mounting frame  67   a , fixed with a carrier  67   b , is fixed on the side wall of the connecting plate  67 . The carrier  67   b  is positioned above the bracket  61 . When rotating to the position of the bracket  61 , the first gripper  62  and the second gripper  63  are rightly positioned on two sides of the carrier  67   b.    
     The third rack  5  is provided with the third gripper  57  capable of rotating around the third axis, and a third rotating cylinder  54  for driving the third gripper  57  to rotate around the third axis. 
     Before looping the rubber band, the first gripper  62  and the second gripper  63  are positioned on two sides of the bracket  61 , and the third axis is positioned between the first axis and the second axis. The radius, by which the third gripper  57  rotates around the third axis, is rightly fitted with the distance from the third gripper  57  to the first gripper  62  and the second gripper  63 . Thus, the third gripper  57  may pass through the unfolded first gripper  62  and second gripper  63 , respectively, while rotating around the third axis. 
     The third rotating cylinder  54  may directly drive the third gripper  57  to move rotationally, or may drive the third gripper  57  to move rotationally via a transmission structure. 
     In this embodiment, the support frame  5   b  of the third rack  5  is provided with a third drive shaft  52  capable of rotating, with the axis of the third drive shaft  52  being coincided with the third axis. The third drive shaft  52  is connected to the third gripper  57  via a third connecting arm  53 . The third gripper  57  may rotate around the third drive shaft  52  where the third axis is located. A third synchronous wheel  52   a  is fixed on the third drive shaft  52 . A fourth synchronous wheel  54   a  is fixedly provided on the drive shaft of the third rotating cylinder  54 . The third synchronous wheel  52   a  is linked to the fourth synchronous wheel  54   a  via a second synchronous belt  54   b.    
     In this embodiment, with a similar structure, the first gripper  62 , the third gripper  63  and the third gripper each comprises a fixed arm  81 , a moving arm  82  and a gripping cylinder  8  for driving the moving arm  82  to coordinate with the fixed arm for gripping. The fixed arm  81  is mounted on the body of the gripping cylinder  8 , while the moving arm  82  is connected to the piston rod of the gripping cylinder  8 . The moving arm  82  may be controlled to coordinate with the fixed arm  81  for gripping under the drive of the gripping cylinder  8 . 
     When in work, the first gripper  62  and the second gripper  63  are positioned on two sides of the bracket  61 , respectively, and are unfolded for gripping. The third gripper  57  grips an end of the rubber band at the discharge port of the second feeding drive wheel  4 , and rotates around the third axis to allow the end of the end of the rubber band to pass through the unfolded first gripper  62  and second gripper  63 . After the first gripper  62  and the second gripper  63  have gripped corresponding portions of the rubber band, the cutting device cuts off the segment of rubber band gripped by the first gripper  62  and the second gripper  63 . At this time, two ends of this segment of rubber band have been gripped by the first gripper  62  and the second gripper  63 . Subsequently, the first gripper  62  and the second gripper  63  move rotationally to the position of the bracket  61 , respectively, where the two ends of the rubber band are fixedly joined on the bracket  61 , and the rubber band is spliced into a ring. The sliding cylinder  51  controls the base  6  to move to convey the first gripper  62 , the second gripper  63  and the bracket  61  to the sewing position for sewing. The air blowpipes  68   a  and the positioning backup plate  68   c  may assist in positioning the looped rubber band, thereby conveying the rubber ring to the sewing device. 
     The distance from the first axis to the second axis can be adjusted by adjusting the mounting positions of the first cylinder mounting plate  62   a  and the second cylinder mounting plate  63   a . During looping a rubber band, the connecting parts are overlapped or spliced as required. When the distance from the first axis to the second axis shortens, two ends of the rubber band are overlapped after the first gripper  62  and the second gripper  63  rotate and fold the rubber band. When the distance from the first axis to the second axis increases, two ends of the rubber band are spliced after the first gripper  62  and the second gripper  63  rotate and fold the rubber band. 
     The preferred embodiment of the present invention has been described above. Various changes or variations made by an ordinary person of skill in the art shall not depart from the scope of the present invention.