Tracking guide bonding machine and method of bonding tracking guide to thermoplastic tape

Abstract

A bonding machine and method for bonding a linear tracking guide to a thermoplastic tape at a splice joint. A heater assembly having two heater halves receives the tracking guide in a trapezoidal channel formed between the two halves. Heat is applied to the heater blocks in each heater half to melt a portion of the base of the tracking guide and an adjoining outer surface of the belt to bond the tracking guide to the belt.

Description

Technical Field

[0001] The present invention relates to a bonding tool and method for bonding a tracking guide to a thermoplastic tape. Background Art

[0002] A splicing press is used to weld the butt ends of two thermoplastic conveyor belt segments together. A conventional press includes a pair of clamps, each clamp holding one of the two belt segments. The clamps extending across the entire width of the belt segment firmly hold the segments so that the butt ends face each other across the gap. A heating wand is moved into the gap and the two clamps are closed until the butt ends of the belt segments contact opposite sides of the heating wand. When the butt ends are sufficiently softened or melted by the heat of the heating wand, the clamps are retracted so that the wand can be removed. The clamps are then moved toward each other until the softened or melted butt ends meet. The clamps hold the butt ends together while the joint at the interface of the butt ends cools.

[0003] Tracking guides are raised ribs that extend linearly at each side edge along the length of the conveying surface of the conveyor belt. Typically, the tracking guide has tapered sides that form a trapezoidal cross-section. The wider base of the tracking guide is attached to the conveying surface of the belt. Since the trapezoidal shape of the tracking guide is an inverted truncated V-shape, the guide is often referred to as a V-guide. A complementary guide structure fixed to the conveyor frame receives the V-guide and prevents the belt from lateral deviation. In other words, the V-guide and the mating guide structure cause the belt to travel along the track. A common form of guide structure is a pulley having a sheave shaped to receive the V-guide.

[0004] When a V-guide is damaged, the damaged section of the V-guide must be replaced. When splicing a belt having a V-guide, the V-guide must also be spliced ​​and reattached to the belt. The process of replacing a V-guide section or splicing a V-guide is a series of labor-intensive operations that require the use of sharp knives, heat guns, grinders, soldering irons, and blowers or vacuum cleaners. Summary of the invention

[0005] One type of bonding machine for bonding a tracking guide to a thermoplastic tape includes a base and a heater assembly. The base has a top surface configured to receive a length of thermoplastic tape having a linear tracking guide. An unbonded length of the linear tracking guide is not bonded to an outer surface of the thermoplastic tape. The heater assembly is located above the base and includes: a channel extending in length from a first end to a second end of the heater assembly; and a first heater block and a second heater block, the first heater block and the second heater block forming a bottom portion of a first side and a second side of the channel. The channel is complementary in shape to the linear tracking guide to fit with the unbonded length of the guide. The first heater block and the second heater block apply heat to melt the bottom of the unbonded length of the tracking guide at the first side and the second side of the channel, thereby bonding the unbonded length of the tracking guide to the outer surface of the thermoplastic tape.

[0006] A method for bonding a tracking guide to an outer surface of a thermoplastic tape, the method comprising: (a) registering a bottom portion of a portion of the thermoplastic tape in a base of a bonding fixture; (b) positioning a first heater half against a first side of an unbonded portion of the tracking guide extending linearly along a length of the thermoplastic tape; (c) positioning a second heater half against an opposite second side of the unbonded portion of the tracking guide; (d) drawing the first heater half and the second heater half together to form a channel between a first heater block in the first heater half and a second heater block in the second heater half, wherein the channel is sized and shaped to (e) cinching the first heater half and the second heater half against the first and second sides of the unbonded portion of the tracking guide; (f) applying downward pressure against the first heater block and the second heater block to press the first heater block and the second heater block against the outer surface of the thermoplastic tape at the bottom of the tracking guide at the first and second sides; and (g) heating the first heater block and the second heater block to melt the bottom of the tracking guide at the first and second sides, thereby bonding the tracking guide to the outer surface of the thermoplastic tape. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is an isometric view of a tracking guide bonder embodying features of the present invention.

[0008] Figure 2 is with Figure 1A similar isometric view, but showing the heater assembly and conveyor belt to be joined separated for clarity.

[0009] Figure 3 yes Figure 1 Exploded view of the heater assembly.

[0010] Figure 4A and Figure 4B yes Figure 1 A top isometric view and a bottom isometric view of a heater assembly in which the heater is split in half.

[0011] Figure 5 yes Figure 1 Bottom isometric view of the heater assembly. DETAILED DESCRIPTION

[0012] Figure 1 A tracking-guide bonder is shown bonding a section of a V-guide to a thermoplastic conveyor belt. The bonding machine 10 is shown bonding a length of a tracking guide (V-guide 12) to the outer surface 14 of a thermoplastic conveyor belt 16 near a splice joint 18. The V-guide 12 is a raised rib that extends linearly along the length of the belt 16, slightly indented into the side edge 20 of the belt. However, the V-guide may alternatively be positioned anywhere across the width of the belt. The belt 16 shown in this example is a homogeneous positive drive conveyor belt made of a thermoplastic material (e.g., polyurethane) having periodically spaced drive rods 22 on the inner side 24 of the belt.

[0013] The bonding machine 10 includes a heater assembly 26 and a fixture 28. The fixture 28 has a top platform 30 connected to a parallel lower base 32 by a pair of side frames 34, 35. A recess 36 in the top surface of the base 32 is sized to receive the drive rod 22 of the belt to keep the belt 16 in registration with the bonding machine 10. A threaded push rod 38 with an adjustment knob 40 extends through a quick release nut 42 and the top platform 30 to a pressure plate 44. The end of the push rod 38 opposite the adjustment knob 40 has a pad 46 that pushes against the pressure plate 44 when the push rod is extended.

[0014] Figure 2 The bonding machine 10 is shown in greater detail with the heater assembly 26 and belt 16 separated from the fixture 28 for clarity. The metal platen 48 of brass, bronze or aluminum is made of thermally insulating PTFE. The liner 50 and the platen 48 form a continuation of the top surface, which includes the groove 36 in the base 32 of the fixture. The platen 48 applies heat to the bottom of the belt 16 to assist the bonding process.

[0015] The incorporation of the V-guide 12 is performed as follows. First, in a separate operation, the two butt ends of the belt 16 are spliced ​​together at the splice joint 18, in which operation the unfixed ends 52, 53 of the V-guide 12 extending from the two butt ends of the belt are separated from the outer surface 14 of the belt. The two separated V-guide ends 52, 53 are cut and aligned so that they meet at the V-guide joint. Then, in a separate operation, the cut ends are spliced ​​together. The V-guide splice can be located at the location of the splice joint 18 of the belt, or it can be offset from this location. After the ends of the V-guide have been tacked together, the outer edge 20 of the belt 16 with the V-guide splice is inserted into the fixing device 28. (In Figure 2 , the belt 16 is flipped relative to its orientation when inserted into the fixture 28 (i.e., so that the V-shaped guide belt edge is deeper into the fixture). The belt drive rod is registered in the groove 36 in the top surface of the base 32. The belt 16 is positioned so that its V-shaped guide 12 rests above the conductive platen 48. See FIG. Figure 2 and Figure 4B , insert the first heater half 54 into the fixture 28 against one side of the V-shaped guide 12. Then, insert the second heater half 55 into the fixture against the other side of the V-shaped guide 12. Turn the thumbscrew 72 to pull the heater halves 54 and 55 toward each other, thereby tightening the heater halves against the V-shaped guide 12. Tighten the push rod 38 against the pressure plate 44, which in turn tightens the heater assembly 26 around the V-shaped guide 12. The heater assembly heats the base of the V-shaped guide and the outer surface 14 of the belt 16 to bond the V-shaped guide to the belt. After the V-shaped guide 12 is bonded to the belt 16, the push rod 38 is raised to disengage it from contact with the pressure plate 44, and the pressure plate is removed from the top of the heater assembly 26. Then, unscrew the thumbscrew 72 to separate the heater halves 54, 55 from the V-shaped guide 12. The belt 16 with the incorporated V-shaped guide 12 is then removed from the fixture 28 .

[0016] exist Figure 3Details of the heater assembly 26 are shown in FIG. The left heater half 54 is nearly identical to the right heater half 55. Each heater half 54, 55 has an aluminum heater block made from two heater block halves 56, 57. A cavity 58 in the facing surfaces of the heater block halves 56, 57 forms a mounting cavity that receives a thermocouple and associated wires (not shown). The thermocouple measures the temperature of the heater block. The bottom of the inner heater block half 56 extends downwardly, slightly lower than the outer heater block half 57. The lower protrusion 60 is a heat applicator that contacts the adjacent outer surfaces of the V-shaped guide and the belt to bond the V-shaped guide in place on the outer surface of the belt. PTFE on the applicator The strips prevent molten plastic from flowing into the heater assembly 26 and also help form a smoother weld line.

[0017] The heater block halves 56, 57 in each heater half 54, 55 are sandwiched between the inner insulation block 62 and the outer insulation block 63. The heater block halves 56, 57 are located in recesses 64, 65 in the lower portions of the insulation blocks 62, 63. Screws 66 passing through aligned holes in the inner insulation block 62 and the heater block halves 56, 57 are screwed into threaded inserts 68 in holes 70 in the outer insulation block 63 to hold the heater block halves 56, 57 all together.

[0018] Two thumbscrews 72 extend through aligned holes in the right heater half 55 and through aligned holes in the left inner insulation block 62 and the left heater halves 56, 57, which are screwed into threaded inserts 74 in holes 76 in the left outer insulation block 63. The thumbscrews 72 are used to close the two heater halves 54, 55 against the V-guide and to release the two heater halves 54, 55 from the V-guide after joining.

[0019] The heater assembly 26 has a first end cap 78 and a second end cap 79 at opposite ends. The first end cap 78 is fixed to the left heater half 54 by screws (not shown), and the second end cap 79 is fixed to the right heater half 55 in a similar manner. Dowels 81 align the end caps 78, 79 with holes 83 in the heater halves 54, 55. Similar to the insulation blocks 62, 63, the end caps 78, 79 are also made of insulation material. Each end cap 78, 79 has a channel 80 in its face 82 facing the heater halves 54, 55. The channel 80 communicates with an inlet 84 in which an air fitting 86 is installed. An air hose (not shown) connected to the fitting 86 forces air through the channel 80 to cool the heater assembly 26 and the V-shaped guide after bonding. If the temperature exceeds the maximum allowable temperature, a thermal fuse 88 in each end cap 78, 79 disconnects the heating circuit for the heater block.

[0020] Wiring to the heater halves 56, 57, thermal fuses 88, and thermocouples extend through openings 90, 91 in the end caps 78, 79 from a terminal block 92, which is attached to the end caps by screws 94. A connector receptacle 96 attached to the terminal block 92 receives a cable plug (not shown) having wires that power the heater block halves 56, 57 and send thermocouple signals to an external controller (not shown) that controls heating power and heating time.

[0021] Figure 4A and Figure 4B The heater assembly 26 is shown with the two heater halves 54, 55 separated from the platen 44. Figure 4B As best shown, the bottom of the end caps 78, 79 has two legs 98, 99 spaced apart across a trapezoidal gap 100, the angled walls of which diverge toward the bottom ends of the legs. The gap 100 is sized and shaped to receive a V-shaped guide. One of the legs 99 of each of the end caps 78, 79 is continuous with the bottom of the outer insulation block 63. Figure 5 As shown, when the heater halves 54, 55 are pulled together by the thumbscrews 72, the bottom sides of the heater halves 54, 55 form a trapezoidal channel 102 that is continuous with the gap 100 in the bottom of the end caps 78, 79. Figure 4A and Figure 4B As shown, the bottom ends of the heater block halves 56, 57 form a portion of each side of the channel 102 for heating the base of the V-guide and the outer surface of the belt.

Claims

1. A bonding machine for bonding a tracking guide to a thermoplastic tape, comprising: a base having a top surface configured to receive a length of thermoplastic tape having a linear tracking guide having an unbonded length that is not bonded to an outer surface of the thermoplastic tape; A heater assembly is located above the base and includes: a passage extending in length from a first end to a second end of the heater assembly; and first and second heater blocks, the first and second heater blocks forming bottom portions of first and second sides of the channel; wherein the channel is complementary in shape to the linear tracking guide to mate with the unbonded length of the tracking guide; wherein the first and second heater blocks apply heat to melt the bottom of the unbonded length of the tracking guide at the first and second sides of the channel to bond the unbonded length of the tracking guide to the outer surface of the thermoplastic tape.

2. The bonding machine according to claim 1, characterized in that: The channel is trapezoidal in shape.

3. The bonding machine according to claim 1, characterized in that: The top surface of the base includes a recess sized to receive a drive rod on the thermoplastic ribbon to maintain the thermoplastic ribbon in registration with the bonding machine.

4. The bonding machine according to claim 1, characterized in that: The base is part of a fixture that also includes a top platform and a pair of side frames connecting the top platform to the base.

5. The bonding machine according to claim 4, characterized in that: The bonding machine includes a push rod extending through the top platform, the push rod being adjustable to push the heater assembly against the linear tracking guide so that the bottom portion of the unbonded length is bonded to the outer surface of the thermoplastic tape.

6. The bonding machine according to claim 1, characterized in that: Each of the first and second heater blocks includes two heater block halves and inner and outer insulation blocks that sandwich the two heater block halves together to form a heat applicator that contacts the unbonded length of the linear tracking guide and the outer surface of the thermoplastic tape to bond the unbonded length of the linear tracking guide to the outer surface.

7. The bonding machine according to claim 6, characterized in that: The bonding machine includes a PTFE strip on the heat applicator to prevent molten plastic from flowing into the heater assembly.

8. The bonding machine according to claim 6, characterized in that The heater assembly includes a first insulated end cap at the first end of the heater assembly and a second insulated end cap at the second end of the heater assembly, wherein the first and second end caps include a gap forming a continuation of the channel in the heater assembly.

9. The bonding machine according to claim 8, characterized in that The bonding machine also includes a thermal fuse in each of the first end cap and the second end cap, the thermal fuse disconnecting power to each of the first heater block and the second heater block when a temperature exceeds a maximum allowable temperature.

10. The bonding machine according to claim 1, characterized in that The base includes a metal platen surrounded by an insulating liner, the metal platen and the insulating liner together forming a continuation of the top surface, and the metal platen applies heat to the thermoplastic tape to help bond the linear tracking guide to the thermoplastic tape.

11. The bonding machine according to claim 10, characterized in that The metal platen is made of brass, bronze or aluminum.

12. The bonding machine according to claim 1, characterized in that The first heater block and the second heater block are separable.

13. A method for bonding a tracking guide to an outer surface of a thermoplastic belt, the method comprising: registering a bottom portion of a portion of the thermoplastic tape in a base incorporating a fixture; positioning a first heater half against a first side of an unbonded length of a tracking guide extending linearly along a length of the thermoplastic tape; positioning a second heater half against an opposite second side of the unbonded length of the tracking guide; drawing the first heater half and the second heater half together to form a channel between a first heater block in the first heater half and a second heater block in the second heater half, wherein the channel is sized and shaped to receive the unbonded length of the tracking guide; cinching the first and second heater halves against first and second sides of an unbonded portion of the unbonded length of the tracking guide; applying downward pressure against the first heater block and the second heater block to press the first heater block and the second heater block against the outer surface of the thermoplastic tape at a bottom of the unbonded length of the tracking guide at the first side and the second side; The first and second heater blocks are heated to melt the bottom portions of the unbonded length of the tracking guide at the first and second sides to bond the unbonded length of the tracking guide to the outer surface of the thermoplastic tape.

14. The method according to claim 13, characterized in that The method includes, prior to registering a bottom portion of a portion of a thermoplastic tape in a base incorporating a fixture: splicing two butted ends of the thermoplastic tape at a splice joint, both butted ends having a length of unbonded tracking guide and at least one of the butted ends including an unbonded tracking guide extending a length; cutting two lengths of unbonded tracking guides and aligning the two lengths of unbonded tracking guides so that the two lengths of unbonded tracking guides meet at a tracking guide joint; The two unjoined tracking guides of a certain length are spliced ​​at the tracking guide joint.

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