magnetic belt clamp

Abstract

A magnetic belt clamp for clamping uniform conveyor belts for cutting or clamping. The magnetic belt clamp includes a clamp bar with one or more magnetic switches along its length. When in the on position, the magnetic switches attract ferromagnetic material in a lower belt aligner, clamping a portion of the conveyor belt in the gap between the bottom of the clamp bar and the aligner. The aligner has alignment structures on the deck that accept protruding belt features to align the belt relative to a guide track, along which a cutting assembly slides to cut a precise line across the belt. A belt cutter or magnetic clamp can be easily attached to the belt splicer to clamp the butt ends of the belts to be spliced.

Description

[Technical Field]

[0001] The present invention relates to a magnetic clamping tool for flexible plastic conveyor belts. [Background technology]

[0002] Belt cutters, such as the THERMODRIVE® line of uniform thermoplastic conveyor belts sold by Intralox, LLC of Harahan, Louisiana, USA, are used to cut flexible plastic conveyor belts to length and make precisely oriented cuts in the belt ends before they are welded together. Precise cuts are especially important in belts with regularly spaced drive teeth. If the cut line is not precisely positioned relative to the teeth, the tooth spacing across the welded cut end will not match the regular tooth spacing or pitch on the rest of the belt. Handheld belt cutters can be used, but a human operator must hold the belt while the handheld belt cutter cuts across its width. Clamps are used to stabilize the belt for cutting or splicing. Clamps often clamp the belt only at its side edges, leaving some slack in the belt's inner region. If the cutter traverses an undulation in the unclamped inner region of the belt, the cut may deviate from a straight line. Summary of the Invention

[0003] One version of the magnetic belt clamp includes a clamp bar that extends from a first end to a second end, a front to a rear, and a top to a bottom. One or more magnetic switches are attached to the clamp bar. The belt aligner is positioned across a gap from the clamp bar and includes a ferromagnetic material and a deck facing the clamp bar across the gap. Alignment structures in the deck are adapted to receive protruding features on the surface of a plastic conveyor belt received in the gap to align the conveyor belt. The one or more magnetic switches are manually adjusted between an off position, which does not exert a magnetic attraction on the ferromagnetic material in the belt aligner, and an on position, which pulls the belt aligner toward the bottom of the clamp bar and clamps the conveyor belt in the gap between the belt aligner deck and the clamp bar.

[0004] One version of the belt cutter includes a magnetic clamp including a clamp bar that extends from a first end to a second end, a front to a rear, and a top to a bottom. A series of mounting holes extend along the length of the clamp bar and through the thickness of the clamp bar from top to bottom. A magnetic switch is attached to each mounting hole. A belt aligner is positioned across a gap from the clamp bar. The belt aligner includes a ferromagnetic material and a deck facing the bottom of the clamp bar across the gap. Alignment structures in the deck receive protruding features on the surface of a plastic conveyor belt received in the gap to align the conveyor belt. The magnetic switch is manually adjusted between an off position, which does not exert a magnetic attraction on the ferromagnetic material in the belt aligner, and an on position, which pulls the belt aligner toward the bottom of the clamp bar and clamps the conveyor belt in the gap between the belt aligner deck and the clamp bar bottom. The belt cutter also includes a cutting assembly including a guide track secured to the front face of the clamp bar and extending along its length, a cutting blade, and a carriage slidably mounted on the guide track and sliding along the guide track to cut off the conveyor belt clamped in the gap along a line outside the gap. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is an isometric view of a belt cutter including a magnetic belt clamp embodying features of the present invention. [Figure 2] FIG. 2 is an exploded view of the belt cutter of FIG. [Figure 3] FIG. 3 is an isometric view of a belt aligner that can be used with the magnetic clamp of FIG. [Figure 4] FIG. 4 is an isometric view of two belt cutters similar to FIG. 1 used in a belt splicer. [Figure 5] FIG. 5 is a front view of the belt splicer of FIG. [Figure 6]FIG. 6 is a top view of the clamp bar of the second version of the magnetic belt clamp. [Figure 7] FIG. 7 is a top view of the clamp bar of the electromagnetic version of the magnetic belt clamp. DETAILED DESCRIPTION OF THE INVENTION

[0006] One version of a belt cutter with a magnetic clamp embodying features of the present invention is shown in FIGS. 1 and 2. The cutter 10 includes a magnetic clamp having a clamp bar 12 that extends from a first end 14 to a second end 15, a width from a front face 16 to a rear face 17, and a thickness from a top face 18 to a bottom face 19. A series of mounting holes 20 extend through the thickness of the clamp bar 12 from the top face 18 to the bottom face 19. In this version, the mounting holes 20 are regularly spaced in a row along the length of the clamp bar 12; however, the spacing can also be irregular or staggered. Each mounting hole 20 is fitted with a magnetic switch 22, such as a magswitch® MAGJIG, available from Magswitch USA, Superior, Colorado. In this version, 14 magnetic switches are used, although more or fewer than 14 magnetic switches could be used.

[0007] Magnetic switch 22 contains two identical, stacked, oppositely polarized permanent magnets within a ferromagnetic housing 24. The lower magnet is stationary, while the upper magnet can be rotated by an upper knob 26. When knob 26 is rotated to the off position, the north pole of the upper magnet is directly above the south pole of the lower magnet, and the south pole of the upper magnet is directly above the north pole of the lower magnet. In this arrangement, magnetic flux is largely confined to housing 24 and the two magnets. Little or no magnetic flux is generated, and therefore no magnetic attractive force is generated outside switch 20. When magnetic switch 20 is rotated to the on position, the north pole of the upper magnet is directly above the north pole of the lower magnet, and the south pole of the upper magnet is directly above the south pole of the lower magnet. In this arrangement, the two magnets effectively become a single magnet that generates magnetic flux outside magnetic switch 20 and can attract nearby external ferromagnetic materials.

[0008] Located below the clamp bar 12 is a belt aligner 28. The belt aligner 28 has alignment structure in the form of an elongated slot 30 recessed into the belt aligner's top deck 32. The elongated slot 30 receives a complementarily shaped protruding feature, such as a drive lug, in the bottom surface of the flexible conveyor belt 34 to be cut. Belts having different protruding features can be received by different belt aligners having corresponding complementary alignment structure in the top deck.

[0009] The side rails 36 at the first and second ends 14 and 15 of the clamp bar 12 are fastened to the ends of the belt aligner 28 by screws 38. The side rails 36 have vertical tracks 40 along which sliders 42 at the first and second ends 14 and 15 of the clamp bar 12 can slide vertically. When the sliders 42 are within the tracks 40, the clamp bar 12 and the belt aligner 32 are aligned. A handle 48 on the top of the clamp bar 12 is used to raise and lower the clamp bar relative to the belt aligner 32. A spring plunger 46 attached to the outside of the side rails 36 has a shaft that passes through the side rails and contacts the slider 42 to stabilize the clamp bar 12. When the plunger is compressed, it releases the clamp bar 12, allowing it to be lifted upward along the side rails 36 by the handle 48 on the top 18 of the clamp bar.

[0010] A portion of the belt 34 is positioned over the belt aligner 28, with the aligner's slots 30 accepting the conveyor belt's drive lugs. The clamp bar 12 is lowered along the side rails 36 and positioned over the belt 34. The magnetic switches 22 are switched to their on position, resulting in an attractive force between the switches and the ferromagnetic material within the belt aligner 28. The attractive magnetic force tightly clamps and stabilizes the conveyor belt 34 in the gap 50 between the belt aligner 28 and the clamp bar 12. The closely spaced magnetic switches 22 clamp the belt with pressure applied substantially uniformly across its entire width, not just on the outside of the belt.

[0011] Belt aligner 28 is shown in more detail in Figure 3. A ferromagnetic insert 47 made of carbon steel or another ferromagnetic material is secured to aligner 28 within a recess in deck 32 directly across a gap 50 from magnetic switch 22, Figure 2. The remainder of belt aligner 28 may be made of aluminum for weight savings; however, the entire belt aligner may be made of carbon steel or another ferromagnetic material.

[0012] The guide track 52 is secured to the front surface 16 of the clamp bar 12. The guide track 52 has an upper groove 54 and a lower groove 55. The carriage 56 has upper and lower legs 58 and 59 that engage the upper and lower grooves 54 and 55 of the guide track 52. The carriage 56 is part of a cutting assembly 60, which further includes a cutting blade 62 and two blade housing halves 64 and 65. The cutting blade 62 is sandwiched between the two housing halves 64 and 65, which are closed around the blade by screws. A thumbscrew 66 in the outer housing half 64 allows for tool-less blade replacement. The inner housing half 65 is secured to the carriage 58. A cutter handle 68 is used to manually slide the cutting assembly 60 along the guide track 52.

[0013] A ledge 70 extends outward from the front face 16 of the clamp bar 12 below the guide track 52. The ledge 70 terminates in a vertical wall that forms a straight edge 72. Because the straight edge 72 is part of the clamp bar 12, which is aligned with the belt aligner 28 and, therefore, with the conveyor belt 34 itself, sliding the cutting assembly 60 along the straight edge of the ledge 70 cuts the belt along a precise line across the width of the belt, a known distance from the protruding feature of the belt, outside the gap 50. Two cutting assemblies 60 are shown in FIGS. 1 and 2; the operator can use whichever is more convenient. However, the belt cutter 10 may also be made with a single cutting assembly 60.

[0014] The belt cutter and splicer 80 of FIGS. 4 and 5 uses two belt cutters with magnetic clamps like those of FIGS. 1 and 2. The belt aligner 28 and side rails 36 are adapted to easily mount on top of the opposing jaws 82 of the belt splicer 84. The jaws 82 are separated by a space 86. The clamp bars 12 are received in the side rails 36. The cutting assemblies 60 on the front faces 16 of the clamp bars 12 face each other across the space 86 and can be used to trim the ends of the belt 34. If belt cutting is not required, the cutting assemblies 60 and guide tracks 52 can be eliminated. A heating rod 88 is movable into the space 86 from below. The splicer 84 includes a mechanism that (a) closes the jaws 82 and moves the butt ends of the conveyor belt 34 together into contact with the sides of a heated heater rod 88, which melts the butt ends; (b) retracts the butt ends from contact with the sides of the heater rod and moves the heater rod out of the space 86; (c) moves the melted butt ends to the same position within the space to join them; and (d) releases the jaws when cooling and joining of the joined butt ends is complete.

[0015] Springs 90 on each end of the jaws 82 are compressed as the jaws move toward each other. The energy stored in the compressed springs 90 is used to rapidly separate the molten belt ends from the sides of the heated rod 88, allowing the rod to move out of the space 88 and the molten belt ends to move into position to form a splice. Further details of the splicer mechanism can be found in U.S. Patent No. 9,796,135, issued October 14, 2017 to Laitram, LLC. The disclosure of that patent is incorporated herein by reference.

[0016] Figures 6 and 7 show alternative versions of the magnetic belt clamp, shown in conjunction with the guide track and cutting assembly. In Figure 6, multiple magnetic switches 92 are embedded at spaced locations across the width of the clamp bar 94. A single on / off lever 96 is coupled to all of the magnetic switches 92 via a rack-and-pinion arrangement, a timing belt and gear arrangement, or an equivalent arrangement that allows all of the magnetic switches to be simultaneously switched between on and off positions. Instead of a permanent magnet, the clamp bar 98 in Figure 7 has a coil 100 wound around its periphery, forming an electromagnetic belt clamp. The coil may have a ferrite core. Power is supplied to the coil by a power cord 102 terminating in a plug 104 that can be plugged into a power source such as a standard outlet. Alternatively, it may be battery-powered. Although not shown, a conventional on / off switch, either on the cord 102 or integral with the clamp bar 98, allows the magnetic clamp to be switched on and off. Thus, an electromagnet that can be selectively switched on and off by an on / off switch is a magnetic switch. Instead of a single coil as in FIG. 7, multiple electromagnets electrically connected in parallel may be spaced apart across the clamping bar to generate the magnetic attraction force.

[0017] All of the magnetic clamps described in the preceding description can have what may be called magnetic switches that can be switched on and off, thus selectively generating a uniform magnetic attraction along the entire length of the clamp bar to apply a substantially uniform clamping force across the entire width of the conveyor belt. Alternatively, non-switchable permanent magnets may be installed in the clamp bar to achieve an equivalent uniform clamping force on the conveyor belt.

Claims

1. A magnetic belt clamp, a clamp bar extending in length from the first end to the second end, in width from the front to the rear, and in thickness from the top to the bottom; one or more magnetic switches attached to the clamp bar; a belt aligner located across a gap from the clamp bar, ferromagnetic material, a deck facing the clamp bar across the gap; a belt aligner including alignment structures in the deck for receiving protruding features on a surface of a plastic conveyor belt received in the gap to align the conveyor belt; the one or more magnetic switches are manually adjusted between an off position, which exerts no magnetic attraction on the ferromagnetic material in the belt aligner, and an on position, which pulls the belt aligner toward the bottom of the clamp bar and clamps the conveyor belt within the gap between the belt aligner deck and the clamp bar.

2. a guide track secured to a front surface of said clamp bar and extending along its length; a cutting assembly including a cutting blade and a carriage slidably mounted on and sliding along the guide track to cut the conveyor belt clamped in the gap along a line outside the gap; 10. The magnetic belt clamp of claim 1, further comprising a belt cutter including:

3. 3. The magnetic belt clamp of claim 2, wherein the clamp bar includes a ledge extending from the front surface to a straight edge, and the cutting assembly travels along the straight edge to ensure a straight cut through the clamped conveyor belt.

4. 3. The magnetic belt clamp of claim 2, wherein the cutting assembly includes a handle for manually sliding the carriage along the guide track to cut the conveyor belt clamped in the gap.

5. 3. The magnetic belt clamp of claim 2, further comprising: a second cutting assembly including a cutting blade and a carriage slidably mounted on and sliding along the guide track to cut the conveyor belt clamped in the gap along a line outside the gap.

6. 2. The magnetic belt clamp of claim 1, comprising a plurality of said magnetic switches, said clamp bar including a series of mounting holes extending through said thickness of said clamp bar from said top to said bottom along said length of said clamp bar, each said magnetic switch mounted in a respective mounting hole.

7. a side rail fastened to the belt aligner and having a longitudinal track, side rails, the clamp bar having sliders at the first and second ends that ride on the longitudinal tracks of the side rails; a handle on the top of the clamp bar for raising and lowering the clamp bar; 10. The magnetic belt clamp of claim 1, comprising:

8. 9. The magnetic belt clamp of claim 8, further comprising a spring plunger extending through the side rail to stabilize the clamp bar and release the clamp bar to remove the conveyor belt from the gap.

9. 2. The magnetic belt clamp of claim 1, wherein the ferromagnetic material magnetically attracts the belt aligner to the one or more magnetic switches in the clamp bar when the one or more magnetic switches are in the on position.

10. The magnetic belt clamp of claim 1 , wherein the alignment structure comprises one or more slots recessed into the deck of the belt aligner.

11. 2. The magnetic belt clamp of claim 1, wherein the one or more magnetic switches comprise two identical, stacked, oppositely polarized permanent magnets within a ferromagnetic housing, one of the two permanent magnets rotatable between an on position in which like poles of the two permanent magnets are aligned and an off position in which opposite poles of the two permanent magnets are aligned.

12. The magnetic belt clamp of claim 1 , wherein the one or more magnetic switches comprise one or more coils forming one or more electromagnets.

13. 1. A belt splicer for splicing together butt ends of conveyor belts, the belt splicer comprising: two opposing jaws spaced apart by a space; a heating rod movable into the space between said jaws; a mechanism for closing the jaws to move the butt ends into contact with the heater rod to melt the butt ends, releasing the jaws to move the butt ends out of contact with the heater rod and move the heater rod out of the space, closing the jaws to move the melted butt ends to the same position to join the butt ends, and releasing the jaws when joining of the butt ends is complete; two magnetic belt clamps according to claim 1 for clamping opposite ends of a conveyor belt to be joined; the front surfaces of the two clamp bars face each other across the space; and The two belt aligners are attached to the two opposing jaws.

14. A belt cutter, A magnetic clamp, a clamp bar including a series of mounting holes along the length of the clamp bar, the mounting holes extending from the first end to the second end, the width from the front to the rear, and the thickness from the top to the bottom, the mounting holes passing through the thickness of the clamp bar from the top to the bottom; a plurality of magnetic switches each mounted in a respective mounting hole; a belt aligner located below the bottom of the clamp bar across a gap extending the length of the clamp bar, ferromagnetic material, a deck facing the bottom of the clamp bar across the gap; a belt aligner including: alignment structures in the deck for receiving protruding features on a surface of a plastic conveyor belt received in the gap to align the conveyor belt; the magnetic switch is then manually adjusted between an OFF position, which exerts no magnetic attraction on the ferromagnetic material within the belt aligner, and an ON position, which pulls the belt aligner toward the bottom of the clamp bar and clamps the conveyor belt within the gap between the deck of the belt aligner and the bottom of the clamp bar; a guide track secured to the front surface of the clamp bar and extending along its length; a cutting assembly including a cutting blade and a carriage slidably mounted on the guide track, sliding along the guide track and cutting the conveyor belt clamped in the gap along an outer line of the gap; A belt cutter comprising a magnetic clamp including:

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