[0001] The present invention is directed to a method for removing insulation from a cable. In particular, the invention is directed to a method to remove cut resistant insulation from a cable without damaging the other components of the cable.

[0002] Certain cable types, such as those used for electric and hybrid vehicles, require several different process steps to prepare them for termination. These process steps include the need to remove insulation, such as silicone, from the outside of the cable and also from the outside of the center conductor. Currently available commercial processes for removing this insulation may nick or cut braid or conductor strands during the removal process, which is unacceptable to certain end users. One process that reduces damage involves using a pair of linear-acting contour blades. When fully closed, these blades produce a circle that closely matches the diameter of the layer beneath the insulation. These blades, however, can produce damage on the sides of the cables where there is a slicing action.

[0003] Another process that is used to reduce damage is to force the cutting edge through the insulation in a radial, or near radial direction. The limitation of using a radial (“pressing”) motion to cut silicone rubber, or similar materials, is that such materials are designed to be abrasion and cut resistant. Applying the radial motion to the cutting blade, against the surface of the insulation material, results in a temporary compression of the insulation material in the immediate blade contact area. After removing the force applied to the blade, the insulation is left intact without being cut.

[0004] The problem to be solved is to provide a method of stripping the insulation from the cable which is effective in removing the insulation without damaging the other components of the cable, such as the braid strands or conductor strands. [0005] This problem is solved by a method of removing insulation from an electrical cable which includes: positioning the cable proximate an insulation cutting blade of a cable preparation apparatus; moving a cutting surface of the insulation cutting blade in a rotary direction relative to the insulation of the cable; engaging the insulation with the cutting surface of the insulation cutting blade as the insulation cutting blade is moved in the rotary direction; cutting the insulation to a defined depth with the cutting surface of the insulation cutting blade as the insulation cutting blade is moved in the rotary direction, the defined depth being less than the thickness of the insulation; thereafter, moving the cutting surface of insulation cutting blade in a radial direction relative to the insulation of the cable; engaging the insulation with the cutting surface of the insulation cutting blade as the insulation cutting blade is moved in the radial direction; and cutting the insulation from the defined depth with the cutting surface of the insulation cutting blade as the insulation cutting blade is moved in the radial direction. The entire thickness of the insulation is cut by the sequential combination of the movement of the insulation cutting blade in the rotary direction and the movement of the insulation cutting blade in the radial direction.

[0006] The invention will now be described by way of example with reference to the accompanying drawings in which:

[0007] FIG. 1 is a perspective front view of an illustrative cable preparation apparatus according to the present invention.

[0008] FIG. 2 is a perspective side view of the cable preparation apparatus of FIG. 1.

[0009] FIG. 3 is a cross-sectional diagrammatic view of a cable with the insulation cutting blades partially cutting through the outer insulation of the cable. [0010] FIG. 4 is an enlarged view of a portion of FIG. 3, showing the displacement of the material of the outer insulation proximate to the insulation cutting blade.

[0011] FIG. 5 is a diagrammatic view of the of insulation cutting blades prior to engaging the cable, the arrows indicated the rotational motion of the insulation cutting blades.

[0012] FIG. 6 is a diagrammatic view of the of insulation cutting blades shown partially cutting through the material of the outer insulation, the arrows indicated the rotational motion of the insulation cutting blades.

[0013] FIG. 7 is a diagrammatic view of the of insulation cutting blades shown partially cutting through the material of the outer insulation, the arrows indicated the radial motion of the insulation cutting blades.

[0014] FIG. 8 is a diagrammatic view of the of insulation cutting blades shown fully cut through the material of the outer insulation, the arrows indicated the radial motion of the insulation cutting blades.

[0015] FIG. 9 is a diagrammatic view of the of insulation cutting blades prior to engaging the inner insulation of the cable, the arrows indicated the rotational motion of the insulation cutting blades.

[0016] FIG. 10 is a diagrammatic view of the of insulation cutting blades shown partially cutting through the material of the inner insulation, the arrows indicated the rotational motion of the insulation cutting blades.

[0017] FIG. 11 is a diagrammatic view of the of insulation cutting blades shown partially cutting through the material of the inner insulation, the arrows indicated the radial motion of the insulation cutting blades.

[0018] FIG. 12 is a diagrammatic view of the of insulation cutting blades shown fully cut through the material of the inner insulation, the arrows indicated the radial motion of the insulation cutting blades. [0019] As shown in FIG. 1, a cable stripping or preparation apparatus 10 has circular base 12 which has a center opening 14 and arcuate slots 16 positioned proximate the circumference of the circular base 12. In the illustrative embodiment shown, three arcuate slots 16 are provided.

[0020] Blade control arms 18 are mounted on the base 12. Mounting members 20 extend through the blade control arms 18 to the base 12. The mounting members 20 pivotally mount the blade control arms 18 to the base 12 to allow the blade control arms 18 to move or pivot relative to the base 12. Each blade control arm 18 has a wheel mounting device (not shown) which extends through the respective slot 16 to mount to a drive wheel mechanism 40. The movement of the drive wheel mechanism 40 causes the blade control arms 18 to pivot about mounting members 20.

[0021] Each blade control arm 18 has a round wheel or braid cutting wheel mounting portion 26 and a contoured or insulation cutting blade mounting portion 28. As shown in FIG. 1, a round wheel or braid cutting wheel 30 is mounted in the round wheel mounting portion 26 and a contoured or insulation cutting blade 32 is mounted in the contoured blade mounting portion 28. The braid cutting wheel 30 is mounted to allow the braid cutting wheel 30 to spin or rotate relative to the round wheel mounting portion 26. The insulation cutting blade 32 is fixedly mounted to the contoured blade mounting portion 28. Each of the insulation cutting blades 32 has an arcuate cutting surface 34, the radius of which may approximate the radius of the cable. Although three insulation cutting blades 32 are shown, other number of cutting blades may be used.

[0022] Referring to FIG. 2, cable preparation apparatus 10 has a first drive wheel mechanism 40 and a second drive wheel mechanism 42 which is spaced from but in line with the first drive mechanism 40. A front or first pulley 44 cooperates with the first drive wheel mechanism 40. The first pulley 44 extends between the first drive wheel mechanism 40 and a front or first drive motor 46. The first drive motor 46 may be, but is not limited to, a servo motor. A back or second pulley 48 cooperates with the second drive wheel mechanism 42. The second pulley 48 extends between the second drive wheel mechanism 42 and a back or second drive motor 50. The second drive motor 50 may be, but is not limited to, a servo motor. A scrap tube 52 extends from the back of the cable preparation apparatus 10.

[0023] The cable stripping or preparation apparatus 10 is just one illustrative embodiment on which the insulation cutting blades 32 can be provided. However, the method as described below can be used with the illustrative cable stripping or preparation apparatus 10 or other types of cable stripping or preparation apparatuses. In addition, the shape of the insulation cutting blade 32 may vary from the description above without effecting the scope of the method.

[0024] In use, the user or operator places an electrical cable 60 between the insulation cutting blades 32 of the cable stripping or preparation apparatus 10. With the cable 60 properly positioned, the apparatus 10 is activated.

[0025] The insulation cutting blades 32 are initially moved to a first position proximate the outer insulation 62 of the cable 60, as shown by dotted line 64 in FIG. 5. The insulation cutting blades 32 are moved to the first position by the first drive wheel mechanism 40. In the first position the insulation cutting blades 32 are positioned proximate to, but do not engage the outer insulation 62.

[0026] With the insulation cutting blades 32 properly positioned in the first position, the insulation cutting blades 32 are spun or rotated in the direction of the arrows 66 shown in FIGS. 5 and 6. While the motion of the cutting blades 32 is shown by arrows 66, other motions of the cutting blades 32 may be used, such as, but not limited to, moving in the opposite direction or moving in a linear direction tangential to the insulation.

[0027] The insulation cutting blades 32 are rotated by the second drive wheel mechanism 42. As the blades 32 are rotated about the longitudinal axis of the cable 60, the arcuate cutting surface 34 of the blades 32 are moved toward the center of the cable 60 until a programed, precise second position, as shown by the dotted line 68 in FIG. 6, is reached. The insulation cutting blades 32 are moved from the first position to the second position by the first drive wheel mechanism 40. As this occurs, the arcuate cutting surfaces 34 of the blades 32 move in a rotary or tangential direction relative to the outer insulation 62 of the cable 60 which allows the arcuate cutting surface 34 of the blades 32 to slice into the outer insulation 62.

[0028] As the blades 32 are moved from the first position to the second position, the blades 32 spin around the circumference of the cable 60, while being driven to a precise depth that partially cuts the outer insulation 62 without completely cutting through the outer insulation 62. In the second position, the blades 32 have cut through more than one-half of the outer insulation 62. The precise depth of the cut is determined and controlled by the size or gauge of the cable and by controlling the cutting dynamics of the blade 32, such as, but not limited to, rotation rate, closing speed, number of rotations, number of chops, depth of chops to impart tensile stress during the process.

[0029] Upon cutting the outer insulation 62 to the precise depth of the second position, the rotation of the blades 32 relative to the cable 60 is stopped. In this position, the blades 32 remain embedded in the outer insulation 62 at the second position depth. As shown in FIGS. 3 and 4, the embedded blade 32 displaces the insulation material 70, creating tension in the outer insulation 62, as indicated by arrows 72, in the area 74 directly beneath the blade 32 (FIG. 4).

[0030] The blades 32 are then moved in a radial, or approximately radial, direction, as shown by arrows 76 in FIGS. 7 and 8. The radial movement of the blades 32 causes the blades 32 to move from the second position shown in FIG. 7 to a third position shown in FIG. 8, in which the blades 32 extend through the outer insulation 62. The insulation cutting blades 32 are moved from the second position to the third position by the first drive wheel mechanism 40. The tension created in the outer insulation 62 by the embedded blades 32 ensures that each radial movement or chop will cut the insulation material 70 in the area 74, rather than only deforming the material. The radial cutting direction and the precise control of the blades 32 ensures that the components of the cable 60 below area 74, such as the braid strands 78 are not cut. A single or multiple radial movement(s) or chop(s) may be used to cut through the outer insulation 62.

[0031] After a radial movement or chop, the blades 32 return to the depth of the second position. The insulation cutting blades 32 are moved from the third position to the second position by the first drive wheel mechanism 40. The blades 32 are then rotated by a pre-set amount, for example 30 degrees, before the next radial movement or chop. The insulation cutting blades 32 are rotated by a coordinated movement of the first drive wheel mechanism 40 and the second drive wheel mechanism 42, in order to maintain the cutting blade depth at the second position during the rotation of the cutting blades 32. The movement of the blades 32 ensures that any insulation that was left uncut between the adjacent contour blades 32 is completely cut. The blades 32 are again moved in a radial, or approximately radial, direction, as shown by arrows 76 in FIGS. 7. The insulation cutting blades 32 are moved in the radial direction by the first drive wheel mechanism 40. The repeat radial movement of the blades 32 causes the blades 32 to move from the second position shown in FIG. 7 to a third position shown in FIG. 8, in which the blades 32 extend through the outer insulation 62, thereby cutting the insulation 62 of the cable 60. This is repeated until all of the insulation in line with the arcuate cutting surface 34 of the blades 32 along the circumference of the cable 60 is cut.

[0032] With the radial movement complete, the arcuate cutting surface 34 of the blades 32 are moved in the radial direction to a predetermined fourth position to prepare for the insulation slug 80 (FIG. 3) removal. The insulation cutting blades 32 are moved from the third position to the fourth position by the first drive wheel mechanism 40. In the fourth position, the blades 32 are spaced from the braid strands 78 beneath the outer insulation 62 while keeping the arcuate cutting surface 34 of the blades 32 engaged with the outer insulation 62. The fourth position may be similar or different than the second position. The cable 60 is then moved in a direction parallel to the longitudinal axis of the cable 60 away from the arcuate cutting surface 34 of the blades 32 so that the blades 32 pull the cut insulation slug 80 from the cable 60. With the slug removed, the arcuate cutting surface 34 of the blades 32 are opened to a distance larger than the circumference of the cable 60 to allow the cable 60 to be moved relative to the blades 32.

[0033] After the removal of the outer insulation 62, foil and the braid strands 78, the insulation blades 32 may also be used to remove the inner insulation 82 from the cable 60. The cable 60 is positioned between the insulation cutting blades 32 of the cable stripping or preparation apparatus 10. With the cable 60 properly positioned, the apparatus 10 is activated.

[0034] The insulation cutting blades 32 are initially moved to a fifth position proximate the inner insulation 82 of the cable 60, as shown by dotted line 84 in FIG. 9. The insulation cutting blades 32 are moved to the fifth position by the first drive wheel mechanism 40. In the fifth position the insulation cutting blades 32 are positioned proximate to, but do not engage the inner insulation 82.

[0035] With the insulation cutting blades 32 properly positioned in the fifth position, the insulation cutting blades 32 are spun or rotated in the direction of the arrows 86 shown in FIG. 9. While the motion of the cutting blades 32 is shown by arrows 86, other motions of the cutting blades 32 may be used, such as, but not limited to, moving in the opposite direction or moving in a linear direction tangential to the insulation.

[0036] The insulation cutting blades 32 are rotated by the second drive wheel mechanism 42. As the blades 32 are rotated about the longitudinal axis of the cable 60, the arcuate cutting surface 34 of the blades 32 are moved toward the center of the cable 60 until a programmed, precise sixth position, as shown by the dotted line 88 in FIG. 10, is reached. The insulation cutting blades 32 are moved from the fifth position to the sixth position by the first drive wheel mechanism 40. As this occurs, the arcuate cutting surfaces 34 of the blades 32 move in a rotary or tangential direction relative to the inner insulation 82 of the cable 60 which allows the arcuate cutting surface 34 of the blades 32 to slice through the inner insulation 82. [0037] As the blades 32 are moved from the fifth position to the sixth position, the blades 32 spin around the circumference of the cable 60, while being driven to a precise depth that partially cuts the inner insulation 82 without completely cutting through the inner insulation 82. In the sixth position, the blades 32 have cut through more than one-half of the inner insulation 82. The precise depth of the cut is determined and controlled by the size or gauge of the cable and by controlling the cutting dynamics of the blade 32, such as, but not limited to, rotation rate, closing speed, number of rotations, number of chops, depth of chops to impart tensile stress during the process.

[0038] Upon cutting the inner insulation 82 to the precise depth of the second position, the rotation of the blades 32 relative to the cable 60 is stopped. In this position, the blades 32 remain embedded in the inner insulation 82 at the second position depth. Similar to that shown in FIGS. 2 and 3, the embedded blade 32 displaces the insulation material, creating tension in the inner insulation 82 in the area directly beneath the blade 32.

[0039] The blades 32 are then moved in a radial, or approximately radial, direction, as shown by arrows 96 in FIGS. 11 and 12. The radial movement of the blades 32 causes the blades 32 to move from the sixth position shown in FIG. 11 to a seventh position shown in FIG. 12, in which the blades 32 extend through the inner insulation 82. The insulation cutting blades 32 are moved from the sixth position to the seventh position by the first drive wheel mechanism 40. The tension created in the inner insulation 82 by the embedded blades 32 ensures that each radial movement or chop will cut the insulation material, rather than only deforming the material. The radial cutting direction and the precise control of the blades 32 ensures that the components of the cable 60 below the blades 32, such as the braid conductors 98 are not cut. A single or multiple radial movement(s) or chop(s) may be used to cut through the inner insulation 82.

[0040] After a radial movement or chop, the blades 32 return to the depth of the sixth position. The insulation cutting blades 32 are moved from the seventh position to the sixth position by a coordinated movement of the first drive wheel mechanism 40 and the second drive wheel mechanism 42, in order to maintain the cutting blade depth at the second position during the rotation of the cutting blades 32. The blades 32 are then rotated by a pre-set amount, for example 30 degrees, before the next radial movement or chop. The insulation cutting blades 32 are rotated by the second drive wheel mechanism 42. The movement of the blades 32 ensures that any insulation that was left uncut between the adjacent contour blades 32 is completely cut. The blades 32 are again moved in a radial, or approximately radial, direction, as shown by arrows 96 in FIGS. 11. The insulation cutting blades 32 are moved in the radial direction by the first drive wheel mechanism 40. The repeat radial movement of the blades 32 causes the blades 32 to move from the sixth position shown in FIG. 11 to the seventh position shown in FIG. 12, in which the blades 32 extend through the inner insulation 82, thereby cutting the inner insulation 82 of the cable 60. This is repeated until all of the insulation in line with the arcuate cutting surface 34 of the blades 32 along the circumference of the cable 60 is cut.

[0041] With the radial movement complete, the arcuate cutting surface 34 of the blades 32 are moved in the radial direction to a predetermined eighth position to prepare for the insulation slug removal. The insulation cutting blades 32 are moved from the seventh position to the eighth position by the first drive wheel mechanism 40. In the eighth position, the blades 32 are spaced from the conductors 98 beneath the inner insulation 82 while keeping the arcuate cutting surface 34 of the blades 32 engaged with the inner insulation 82. The eighth position may be similar or different than the sixth position. The cable 60 is then moved in a direction parallel to the longitudinal axis of the cable 60 away from the arcuate cutting surface 34 of the blades 32 so that the blades 32 pull the cut insulation slug from the cable 60. With the slug removed, the arcuate cutting surface 34 of the blades 32 are opened to a distance larger than the circumference of the cable 60 to allow the cable 60 to be moved relative to the blades 32.