Method and apparatus for splitting leather using a laser

A method and apparatus for splitting leather wherein the leading end of a length of leather is held between a pair of calendar rolls, and a focused laser beam is caused to sweep across the leading end of the length of leather to cut a first layer of leather away from a second layer. A rotating mirror assembly is provided for directing the focused laser beam against the face of the leather and for causing the beam to sweep across the face of the leather.

FIELD OF THE INVENTION 
The invention is directed to a method and apparatus for splitting leather. 
BACKGROUND PRIOR ART 
Manufacture of products made of leather requires splitting pieces of 
leather to reduce the thickness of the pieces of leather before they can 
be used in the production of leather products. 
In the prior art methods for splitting leather to reduce its thickness, 
pieces of leather are fed between a pair of horizontal rollers or calendar 
rolls. The rollers clampingly engage the upper and lower surfaces of the 
leather to hold that portion of the leather in place. A horizontally 
extending blade engages the leading edge of the piece of leather held 
between the rollers and forms a horizontal cut in the leather. The lower 
layer can be removed leaving a top layer for use in the manufacturing 
operation. The horizontally extending blade can comprise a flexible 
endless band with the blade moving across the leading edge or face of the 
leather and in a direction perpendicular to the direction of movement of 
the leather between the rollers. 
One of the problems with such prior art arrangements is that the continuous 
moving blades or bands require replacement at frequent intervals. This 
results in substantial cost for replacement of the blades and down time of 
the leather splitting machines. 
Another problem with the prior art apparatus is that when the blades become 
dull or damaged, they can cause an increased generation of scrap and can 
result in waste of a great deal of leather. 
Attention is directed to the Cannon et al. U.S. Pat. No. 4,029,535, issued 
June 14, 1977; the Miller U.S. Pat. No. 4,500,771, issued Feb. 19, 1985; 
IBM Technical Disclosure Bulletin, Volume 20, No. 11B, April 1978, pages 
4939-4940 and IBM Technical Disclosure Bulletin Volume 22, No. 6, November 
1979, pages 2463-2464. 
Attention is further directed to the Houldcroft U.S. Pat. No. 3,612,814, 
issued Oct. 12, 1971; the Ehlesheid et al. U.S. Pat. No. 4,049,945, issued 
Sept. 20, 1977; and the Stemmler et al. U.S. Pat. No. 4,160,894, issued 
July 10, 1979. 
SUMMARY OF THE INVENTION 
The present invention provides an improved method and apparatus for 
splitting leather which avoids the deficiencies of the prior art in 
connection with replacing blades. 
The present invention includes a method for splitting leather wherein a 
focused laser beam is caused to sweep across the leading edge of a piece 
of leather clampingly held between a pair of calendar rolls to cut the 
leading edge of the leather and to thereby separate one layer of leather 
material from the remainder of the leather. A rotating mirror assembly can 
be employed to cause the focused laser beam to repeatedly sweep across the 
leading edge of the leather piece to form a narrow cut in the leather and 
thereby split the leather or separate the lower layer of leather from the 
remainder of the leather. 
More particularly, the invention includes a method for splitting leather 
including the steps of supporting a piece of leather between a pair of 
rollers, with a leading edge of the piece of leather clamped between the 
rollers, and feeding the piece of leather between the rollers in a first 
direction. The method also includes providing means for producing a laser 
beam, focusing the laser beam such that the laser beam will have a focal 
point between the rollers, and causing the laser beam to sweep across the 
leading edge of the layer of leather, with the beam moving in a plane 
parallel to the opposite surfaces of the piece of leather and between the 
opposite surfaces of the piece of leather, and with the focal point of the 
laser beam striking the leading edge of the piece of leather between the 
opposite surfaces and cutting the leather to separate the layer of leather 
into two layers. 
In one form of the invention the step of causing the laser beam to sweep 
across the leading edge of the layer of leather includes the steps of 
providing a mirror supported for rotation around an axis perpendicular to 
the layer of leather, causing rotation of the mirror about that axis, and 
directing the laser beam against the mirror whereby rotation of the mirror 
about the axis will cause the laser beam to repeatedly sweep along the 
length of the leading edge of the layer of leather to cut the leather 
between the opposite surfaces of the layer of leather. 
In one form of the invention the method further includes the step of 
directing jets of noncombustible gas at the leading edge of the layer of 
leather to prevent charring of the leather material and to disperse any 
particles from the path of laser beam. 
The invention also includes an apparatus for splitting a piece of leather, 
the apparatus including a pair of spaced apart rollers adapted to 
clampingly engage and secure a piece of leather therebetween, one of the 
rollers engaging one surface of a leading edge of the piece of leather and 
the other of the rollers engaging the other surface of the leading edge of 
the piece of leather. Means are also provided for causing rotation of the 
rollers to cause movement of the piece of leather through the space 
between the rollers and in a first direction of movement. The apparatus 
also includes a laser for generating a laser beam, and means for focusing 
the laser beam such that the laser beam will include a focal point. Means 
are also provided for causing the focal point of the laser beam to 
repeatedly sweep along the leading edge of the piece of leather clampingly 
engaged between the rollers and from adjacent one edge of the piece of 
leather to adjacent the opposite edge of the piece of leather in a line 
parallel to the opposite surfaces of the piece of leather. As the focal 
point of the laser beam sweeps along the length of the leading edge of the 
leather, the laser beam cuts the leather to separate one layer of the 
piece of leather from a second layer of the piece of leather. 
In one form of the invention the means for causing the focal point of the 
laser to sweep along the leading edge of the piece of leather includes a 
mirror assembly, the mirror assembly including a plurality of mirror 
surfaces joined together in edge-to-edge relation and surrounding a 
central axis of rotation, and the mirror surfaces facing outwardly with 
respect to the central axis of rotation. 
In one embodiment of the invention means are further provided for 
discharging non-combustible gas toward the leading edge of the piece of 
leather where the focal point of the laser beam strikes the leading edge 
of the piece of leather. 
In one embodiment of the invention means are further provided for 
separating one layer of leather from the other layer of leather. The means 
for separating includes a diverter blade having an edge adjacent the 
leading edge of the piece of leather, and the edge of the diverter blade 
includes a pluraltiy of gas discharge ports for discharging the 
non-combustible gas toward the leading edge of the piece of leather. 
Various other features and advantages of the invention will be apparent by 
reference to the following description of a preferred embodiment, from the 
claims and from the drawings.

Before describing the invention in detail, it is to be understood that the 
invention is not limited in its application to the details of construction 
and to the specific arrangement of the components set forth in the 
following description or illustrated in the drawings. The invention is 
capable of other embodiments and of being practiced and carried out in 
various ways. Also, it is to be understood that the phraseology and 
terminology employed herein are for the purpose of description and should 
not be regarded as limiting. 
DESCRIPTION OF A PREFERRED EMBODIMENT 
Illustrated in FIG. 1 is an apparatus embodying the present invention and 
for use in splitting pieces of leather to reduce the thickness of the 
leather and to produce thin pieces of leather to be used in manufacturing 
operations. 
The apparatus includes a means for supporting a piece of leather 10 and 
means for feeding the piece of leather 10 between a pair of calendar rolls 
or rollers 12 and 14. The apparatus for supporting the leather and for 
feeding it to the calendar rolls is conventional and is not shown. The 
piece of leather 10 is fed between the pair of calendar rolls 12 and 14 
and is clampingly engaged between those rolls such that it is held firmly 
in position. The calendar rolls 12 and 14 provide a means for firmly 
securing the leather in a horizontal flat relationship and for securing 
the leading end, or portion of the leather to be cut, firmly in place so 
that an accurate cut can be made across the leading edge of the piece of 
leather. 
While in the illustrated arrangement the calendar rolls 12 and 14 are shown 
as being positioned such that they are rotatable about horizontal axes and 
vertically spaced apart from one another, it will be understood by those 
skilled in the art that in other arrangements the leather and calendar 
rolls could be positioned in other orientations. 
Means are also provided for generating a laser beam 16 and for causing that 
laser beam 16 to sweep across the leading edge of the piece of leather 
positioned between the calendar rolls and such that the laser beam can cut 
the leading edge of the leather to separate a lower layer of the leather 
from an upper layer. The means for generating the laser beam 16 includes a 
conventional laser 18 of the type commonly used in industrial 
applications. For example, a conventional carbon dioxide laser can be 
employed. 
Means are also provided for focusing the beam 16 generated by the laser 18 
such that the energy of the light at the focal point of the beam is 
sufficiently concentrated that it will efficiently vaporize the leather 
material struck by the focal point of the laser beam to cut the leather 
and to separate a lower layer of leather from an upper layer. A common 
commercially available laser will normally generate a beam of light which 
is approximately 3/8 inches in diameter. The energy of this beam of light 
is ineffective to cut the leather material. However, if the beam is 
focused, the energy of the light at the focal point can effectively 
vaporize the leather material. In the illustrated arrangement the means 
for focusing the beam comprises a lens 19, and the lens 19 is constructed 
such that the focal point of the laser beam will be located in the space 
between the calendar rolls 12 and 14. 
Means are also provided for causing the focal point of the beam 16 from the 
laser 18 to sweep across the face of the leading edge of the leather such 
that the focal point of the laser beam will make successive shallow cuts 
in the leather as it sweeps across the face of the leather as seen in FIG. 
3. In the illustrated arrangement, the means for causing the focal point 
of the laser beam to sweep across the leading edge of the leather from one 
side of the piece of leather to the other comprises a mirror assembly 22 
supported for rotation about a central vertical axis perpendicular to the 
horizontal planes defined by the upper and lower surfaces 24 and 26 of the 
leather. The mirror assembly 22 includes a plurality of planar mirrors 28 
each having vertical edges 30, and the mirrors 28 are positioned in 
edge-to-edge abutting relation so as to form a polygon of reflecting 
surfaces facing outwardly with respect to the axis of rotation of the 
mirror assembly 22. 
In the illustrated arrangement the mirrors 28 are mounted or supported such 
that they define an acute angle with respect to the vertical axis of 
rotation of the mirror assembly 22 and such that the mirros slope upwardly 
and outwardly, the angle of the mirros with respect to the vertical axis 
of rotation of the mirror assembly being such that a beam 16 emitted by 
the laser will be reflected by the mirror and strike the leading edge of 
the piece of leather. 
While in the illustrated arrangement the mirror assembly is comprised of 
eight mirrors 28 placed in edge-to-edge relation so as to form an octagon, 
in other arrangements fewer or more mirrors could be employed in the 
mirror assembly 22, and the polygon defined by the mirrors could have more 
or fewer than eight sides. 
Means are also provided for causing rotation of the mirror assembly 22 
about the central vertical axis of rotation such that the laser beam 16 
reflected by the mirrors will be caused to repeatedly sweep across the 
face of the leading edge of the length of leather from one edge 32 of the 
leather to the other edge 34 and in a plane parallel to and between the 
upper and lower surfaces 24 and 26 of the piece of leather. As best 
illustrated in FIG. 3, as a panel of the mirror assembly rotates around 
the central vertical axis of the mirror assembly, the beam 16 reflected by 
one of the mirrors, will move through an acute angle, and the focal point 
of the focused laser beam 16 will move rapidly from one edge 32 of the 
piece of leather to the opposite edge 34. 
While various apparatus could be provided for causing rotation of the 
mirror assembly, in the illustrated arrangement the mirror assembly 22 can 
be fixedly mounted on the shaft of a hysteresis sychronous motor 40. 
Suitable motors are manufactured by Vernitech, 300 Marcus Boulevard, Deer 
Park, N.Y. 11729. 
In some conventional leather splitting operations an entire hide is split 
and the rollers may be 8 feet in length. When the distance between the 
opposite edges of the piece of leather is large, a lens assembly of the 
type illustrated in IBM Technical Disclosure Bulletins, Vol. 20, No. 11B, 
April 1978, pages 4939-4940 and Vol. 22, No. 6, November 1979, pages 
2463-2464 can be employed to cause the focal point of the laser beam to 
trace a linear path as it moves along the length of the leading edge of 
the piece of leather held between the rollers. 
While in the illustrated arrangement the laser is shown as being positioned 
below and to the side of a line extending from the mirror assembly to the 
calendar rolls, in other applications the mirror assembly could be 
constructed such that the laser could be positioned in other locations 
with respect to the mirror assembly and calendar rolls. For example, the 
laser could be positioned beneath the mirror assembly with the laser 
directed upwardly and with the mirror assembly having a configuration such 
that the laser beam emitted by that laser will be reflected so as to be 
directed against the leading edge of the piece of leather. 
In the illustrated form of the invention, means are also provided for 
separating the scrap layer or substrate 42 of leather material from the 
upper layer 44. In the illustrated construction, this means is comprised 
of a part diverter 46 positioned above the laser beam. The upper part 
diverter 46 includes a blade edge 48 positioned above the plane of the 
sweeping laser beam and adjacent the leading edge of the leather or the 
area where the laser beam strikes the leading edge of the leather piece. 
The diverter blade 48 causes the upper portion or layer of the leather to 
be carried upwardly away from the laser beam. The apparatus also includes 
a thin plate 47 having an upper surface for supporting the upper layer of 
leather. The upper layer of leather is then removed from the supporting 
plate 47 by the operator. The lower layer of leather can fall into a 
collecting bin. 
In one embodiment of the invention, means are also provided for directing a 
non-combustible gas toward the leading edge of the piece of leather as the 
laser beam focal point sweeps across the leading edge of the leather from 
one edge of the leather to the opposite edge. This means for directing a 
non-combustible gas toward the leading edge of the piece of leather 
functions to prevent charring or any excess burning of the leather 
material and also disperses any particles from the path of the focal point 
of the laser beam. If the area adjacent the leading edge of the leather 
includes particles entrained in the air, the efficiency of operation of 
the laser beam is reduced. While various means could be provided for 
directing a non-combustible gas at the face of the leather, in the 
illustrated arrangement the diverter plate 46 is provided with a plurality 
of gas outlet ports 50 spaced apart along its forward edge and facing the 
opposed leading edge of the piece of leather. The diverter plate 46 can 
include a plenum chamber 52 therein (FIG. 4) extending along its length 
and connected by a conduit 54 (FIG. 5) to a source of noncombustible gas, 
such as nitrogen. Nitrogen can be supplied under pressure to the plenum 
chamber 52 in the diverter plate 46 and will be discharged toward the 
leather through the discharge ports 50. The ports 50 will function as 
nozzles to direct the nitrogen toward the leading edge of the leather and 
causing oxygen in that area to be dispersed. In operation, as the laser 
beam sweeps across the face of the leading edge of the leather, the 
leather material will be cut by the laser beam and combustion will be 
prevented because of the absence of oxygen in the immediate area of the 
leading edge of the piece of leather. The jets of nitrogen directed 
against the face of the leather will also function to remove heat from the 
leather and will prevent the laser beam from generating heat in the piece 
of leather which would otherwise damage the leather. This is true 
particularly because the nitrogen gas is directed at the specific area of 
the face of the leather, where the leather is burned by the focal point of 
the laser beam. The jets of gas will also disperse any random particles 
from the path of the focal point of the laser beam thereby improving the 
efficiency of operation of the laser.