Apparatus and method for radially cutting cylindrical material

An apparatus for radially cutting cylindrical material including three rollers mounted with a first frame which is pivotable about an axis of one of the rollers with respect to a second frame which carries a saw arbor. One of the rollers is driven in rotation by a motor, and is geared to the saw arbor to drive the saw blades in rotation. A second roller is movable with respect to the first frame and the first roller, and a third roller is mounted on a hydraulic cylinder to clamp the three rollers against the exterior surface of a cylindrical material. Axial grooves are located on the drive roller to facilitate driving of the material, and circumferential grooves are provided on one of the other rollers to prevent axial displacement of the material subsequent to clamping. A ball screw unit pivots the first frame with respect to the second frame to cause the saw blades to engage the material and make radial cuts into the material. A process for radially cutting cylindrical material is also disclosed herein.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an apparatus and method for radially 
cutting cylindrical material, and more particularly to an apparatus and 
method which clamps the cylindrical material at its exterior for sawing of 
the material. 
2. Description of the Prior Art 
The present invention provides an apparatus and method which clamps the 
exterior of a cylindrical material and radially saws into the material. 
The invention provides a simple and rugged device which is adaptable to 
cutting different sizes, shapes and lengths of material. Several radial 
cuts may be simultaneously made with accuracy and precision, and minimal 
wastage of material and wear to the components of the apparatus result. In 
contrast, many of the devices of the prior art have been relatively 
complex, wasteful and difficult and time consuming to use. 
In U.S. Pat. No. 3,906,821, issued to Schultz on Sept. 23, 1975, there is 
disclosed an apparatus for separating plastic containers. The Schultz 
device comprises a complex arrangement of lever arms which carry three 
pairs of rollers to clamp against the threaded neck portions of the 
plastic bottles. Knife blades are moved against the mouths of the bottles 
to cut through and thereby separate the bottles. A first motor drives two 
pairs of the rollers through a series of belt and pulley arrangements, and 
a second motor drives a series of cams to actuate the movement of the 
rollers and the knife blades. 
A ring cutting machine is disclosed in U.S. Pat. No. 2,771,662, issued to 
Ziska on Nov. 27, 1956. Three rollers are carried on a frame which pivots 
at a fourth location relative a base. The rollers are positionable to 
clamp against the exterior of a cylindrical tube, and each of the rollers 
is driven through a series of belts and pulleys. A gang saw assembly is 
mounted to the base and is driven by a separate motor. The Ziska device 
operates to cut tubular material into several rings by first pivoting the 
roller frame down to cause the saw blades to fully cut through the 
stationary tubular material at one point. Once the material has been cut 
through, the material is slowly rotated in a full circle to provide 
cutting around the full circumference, thus producing several ring-shaped 
pieces. In U.S. Pat. No. 3,107,564, issued to Coker et al. on Oct. 22, 
1963, there is also disclosed a tube cutting machine utilizing three 
rollers to clamp the material and a saw blade pivoted at a fourth location 
relative the rollers to effect cutting. Both the Ziska and Coker et al. 
devices exemplify the relatively complex assemblies existing in the prior 
art. 
In U.S. Pat. No. 3,797,338, issued to Molnar on Mar. 19, 1974, there is 
disclosed a machine for mass production of lengths of tubing. The Molnar 
device includes a rotating drum having several shelfs extending radially 
therefrom. Upon rotation of the drum into the cutting position, a length 
of material rests on the shelf and is held against the shelf and drum 
surface by a belt extending thereover. A drive roll for a ring splitting 
machine is disclosed in U.S. Pat. No. 1,908,695, issued to Deutsch on May 
16, 1933. The drive roll in the Deutsch device is received within tubular 
material to be cut and holds the material against two rollers positioned 
outside of the tube. In U.S. Pat. No. 3,541,905, issued to Mey on Nov. 24, 
1970, there is disclosed a cutting apparatus in which tubular material is 
held by a pair of rollers having a belt passing around more than half the 
circumference of the tubular material. Other supports for cylindrical 
material are disclosed in U.S. Pat. Nos. 3,302,285, issued to Mann on Feb. 
7, 1967; 2,753,744, issued to Therien on July 10, 1956; 2,042,794, issued 
to Meyer on June 2, 1936; and, 1,017,037, issued to Borden on Feb. 13, 
1912. 
The above prior art devices and methods provide suitable means for radially 
cutting into particular types of cylindrical material. However, many of 
these devices are relatively complex in structure and operation, and 
certain of these devices are not readily adaptable to operation in heavier 
duty applications, such as cutting metals or solid cylindrical stock. The 
prior art devices also are typically not well suited to making several 
cuts simultaneously, and are not adaptable for cutting different sizes, 
shapes and lengths of material. The present invention overcomes these 
disadvantages, and also provides a simple, rugged, inexpensive device and 
method which are readily operated to provide accurate and precise cuts of 
varying types with a minimal wastage of material and time. 
SUMMARY OF THE INVENTION 
In one aspect, the present invention provides an apparatus for radially 
cutting cylindrical material which includes three rollers mounted with a 
first frame and pivotable with respect to a second frame which carries one 
or more saw blades. The three rollers are positionable to clamp the 
exterior cylindrical surface of the material to be cut. Means are provided 
for driving the saw blades and at least one of the rollers in rotation to 
simultaneously rotate the material and saw blades during the cutting 
operation. In another aspect, circumferential and axial grooves are 
provided on one or more of the rollers to facilitate the clamping and 
rotating of the material by the rollers. A process for making radial cuts 
into material having a cylindrical exterior surface, and other aspects of 
the present invention, are also disclosed and claimed herein. 
It is an object of the present invention to provide a simple, durable and 
relatively inexpensive apparatus and method for radially cutting 
cylindrical material. 
It is another object of the present invention to provide an apparatus and 
method for making accurate and precise radial cuts into cylindrical 
material, and for making several simultaneous cuts. 
It is a further object of the present invention to provide an apparatus and 
method which is readily adaptable for radially cutting cylindrical 
material of differing sizes, shapes and lengths. 
Another object of the present invention is to provide an apparatus and 
method for radially cutting cylindrical material with a minimal waste of 
time and material. 
Further objects and advantages of the present invention will become 
apparent from the description of the preferred embodiment which follows.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
For the purposes of promoting an understanding of the principles of the 
invention, reference will now be made to the embodiment illustrated in the 
drawings and specific language will be used to described the same. It will 
nevertheless be understood that no limitation of the scope of the 
invention is thereby intended, such alterations and further modifications 
in the illustrated device, and such further applications of the principles 
of the invention as illustrated therein being contemplated as would 
normally occur to one skilled in the art to which the invention relates. 
The present invention provides an apparatus and method for simultaneously 
making several radial cuts into material having an exterior cylindrical 
surface. The apparatus is a relatively simple and durable device which 
will make several radial cuts with high accuracy and precision. The 
material to be cut may be easily and quickly loaded into and unloaded from 
the apparatus, and a variety of lengths and diameters of the material may 
be accommodated. The present invention operates rapidly and economically 
and minimizes wastage of material. 
Some of the principles of the invention are represented in FIGS. 1 and 2. 
As shown in FIG. 1, the material to be cut 10 is held between rollers 
11-13. The rollers are mounted to a first frame 14. A saw blade assembly 
15 is mounted to a second frame 16. The first frame 14 is pivotally 
mounted to the second frame 16 to feed the material 10 against the saw 
blades of the saw blade assembly. Means are provided for positioning the 
three rollers to clamp against the material 10, and further means are 
provided for rotating one of the rollers to drive the material 10 in 
rotation. Drive means are provided for rotating the saw blade assembly 15, 
and means are also provided for pivoting the first frame relative the 
second frame to feed the material 10 against the saw blades of the saw 
blade assembly 15 to effect radial cutting of the material. 
First frame 14 includes several components, including a pair of parallel 
plates 17 and 18 connected at one end by cross members 19 and 20. As will 
be further described, the other ends of the plates 17 and 18 are connected 
together by the mounting of the rollers 11-13 and the pivotable connection 
with the second frame 16. The firm connection between plates 17 and 18 
which is thereby obtained provides strength and rigidity to the first 
frame. These features are advantageous in properly supporting the rollers 
and the clamping action provided by the rollers. The strength and rigidity 
also provide for accurate and precise cuts by the apparatus. In a 
preferred embodiment, the plates 17 and 18 are spaced at a distance of 10 
inches and have a thickness of 11/4 inches, with the end cross member 19 
having a thickness of 2 inches and the top cross member 20 having a 
thickness of 2 inches. The plates are typically made of hot rolled steel 
or other suitable material. Other combinations of distances and 
thicknesses which provide adequate strength and rigidity for the first 
frame are useful in the apparatus. 
The second frame 16 similarly includes several components which combine to 
form a strong and rigid unit. Second frame 16 includes a pair of parallel 
plates 21 and 22 secured with bolts 23 (FIG. 3) to a base plate 24. In a 
preferred embodiment, the plates 21 and 22 are spaced at a distance of 
121/2 inches, to rest adjacent the plates 17 and 18 of the first frame, 
and the plates 21 and 22 and base plate 24 have a thickness of 2 inches. 
Again, a typical material for such plates is hot rolled steel, and other 
combinations of distances and thicknesses which provide suitable strength 
and rigidity are useful in the apparatus of the present invention. 
Pivot means are provided for pivoting the first frame 14 relative the 
second frame 16 about a first axis. As shown in the drawings, the first 
and second frames are pivotable with respect to one another about axis 25. 
First frame 14 pivots relative second frame 16 about a shaft 26 which is 
mounted by bearing means to the first and second frames. Bearing means 
mounting shaft 26 include bearings 27 received within the parallel plates 
21 and 22 and bearings 28 received within the parallel plates 17 and 18. 
For these and similar bearings used in the present apparatus, it is 
preferable to use sealed bearings or to otherwise provide for protecting 
the bearings, such as by sealing the bearing races with an o-ring seal 
received in an annular groove adjacent the bearing races. Shaft 26 
includes circumferential grooves 29 within which are received snap rings 
30. The snap rings are positioned adjacent the inner faces of plates 17 
and 18 and retain shaft 26 in position relative thereto. Bolts 31 are 
received in the exterior faces of plates 21 and 22 and retain the bearings 
27 therein. Shaft 26 is thereby rotatable about axis 25 and relative the 
first and second frames, and the first and second frames are also 
pivotable with respect to one another about the shaft 26 and axis 25. As 
described, the second frame 16 would typically be secured to the floor or 
another support and the first frame would be movable with respect to this 
support. It will be appreciated, however, that either of the first and 
second frames may be stationary to a support surface, with the important 
aspect being the pivoting of one with respect to the other. 
Roller 11 is received upon shaft 26 and secured thereto with bolts 32 (FIG. 
5) which project through the roller 11 and into the shaft 26. 
Alternatively, a two piece roller may be used to facilitate removal of the 
roller. Roller 11 being attached to shaft 26 will therefore rotate along 
with shaft 26 about axis 25. As shown, roller 11 is mounted by bearing 
means to both the first frame plates 17 and 18 and the second frame plates 
21 and 22. It will be appreciated, however, that pivotal movement between 
the first frame plates and second frame plates about axis 25 could be 
achieved with roller 11 mounted to only one or the other of the pairs of 
plates. The depicted embodiment is advantageous in that it provides a 
simple, and yet precise, mounting of the pairs of plates to pivot with 
respect to one another, and also to have the pivoting of the plates and 
the rotation of the roller 11 about the same axis 25. 
Roller 12 is mounted to the first frame plates 17 and 18. Roller 12 may 
suitably be mounted to the first frame plates in a fixed position (not 
shown) in the same manner as roller 11. More desirably, roller 12 is 
mounted to be movable relative the roller 11. In a preferred embodiment, 
side plates 33 and 34 are rotatably mounted to the first frame plate 17 
and 18, respectively. Each of the side plates includes a cylindrical 
portion 35 centered into a cylindrical recess in the first frame plates to 
provide for rotating of the side plates. A plurality of threaded holes, 
such as 36 (FIG. 4), are located adjacent reduced diameter portions of the 
side plates. Bolts 37 are received through clamping members 38 and in the 
holes 36 to press the clamping members against the side plates to hold 
them in a particular rotational position. Similarly, slots 39 are defined 
in larger diameter portions of the side plates, and threaded holes 40 
(FIG. 4) receive bolts 41 and washers 42 which clamp against the side 
plates and maintain the side plates in a particular position. 
Alternatively, roller 12 may be positionable at differing locations 
directly in the first frame plates 17 and 18, or other variable mounting 
methods may be employed. 
Bearing means are provided for mounting the roller 12 to the parallel 
plates 17 and 18 of the first frame 14. Roller 12 includes a body portion 
and reduced diameter axle portions 43 at each end of the body portion. The 
axle portions 43 are received within bearings 44 (FIG. 5) which are in 
turn mounted within corresponding apertures in the side plates. Roller 12 
is thereby mounted to be rotatable about a central axis 45 which is 
parallel to the axis 25. 
Rollers 11 and 12 are mounted at a distance from each other less than the 
diameter of the material to be cut. The provision of variable mounting 
locations for the roller 12 provides a more versatile unit readily adapted 
for use with a variety of sizes of material. 
Third roller 13 is mounted with bearing means to the first frame member 14 
to rotate about a third axis 46 (FIG. 6) parallel to axes 45 and 25. Clamp 
and release means are provided for positioning the third roller 13 in a 
first, clamped position relative the rollers 11 and 12 to clamp the 
rollers against the exterior surface of the material 10, as shown in full 
lines in FIGS. 1 and 4. The clamp and release means also are provided for 
positioning the roller 13 in a second, unclamped position displaced 
farther from the rollers 11 and 12 than in the first or clamped position, 
the unclamped position being shown in dotted lines in FIG. 1 at the 
identification numeral 47. In the clamped position, the three rollers 
engage the exterior surface of the material to be cut and hold it firmly 
in position. Further, the clamping of the three rollers against the 
exterior surface of the material provides for rotation of the material 10 
upon driven rotation of one or more of the adjacent rollers. In the 
second, unclamped position the material 10 may be placed into or removed 
from the rollers, such as for insertion of a new piece of material to be 
cut or removal of the cut material. 
A hydraulic cylinder 48 is mounted to the rear cross member 19 of the first 
frame. Piston 49 is reciprocally received within the hydraulic cylinder 
48, and hydraulic lines, such as 50 (FIGS. 1 and 4) are connected to a 
source of hydraulic fluid, and under appropriate control will provide 
controlled reciprocation of the piston 49 with respect to the cylinder 48. 
A yoke 51 comprising a pair of arms 52 and 53 mounted to a base 54 with 
bolts 55 (FIG. 6) is secured to the piston 49. A pair of bearings 56 are 
mounted within the arms 52 and 53. Roller 13 includes a body portion 57 
and axle portions 58 at either end of the body portion and received within 
the bearings 56 (FIG. 6). Roller 13 is thereby rotatably mounted by the 
bearing means, including bearings 56, to rotate about axis 46 parallel to 
the other roller axes 25 and 45. 
Hydraulic cylinder 48 is operable to move the roller 13 to and from the 
clamping position as shown in FIG. 4 and the released position as shown at 
47 in FIG. 1. In the clamped position, the hydraulic cylinder applies 
pressure through the piston 49 to clamp the roller 13 against the material 
10 to force it against the other rollers 11 and 12. This maintenance of 
pressure causes the material to be firmly held between the three rollers 
during the cutting operation. An accumulator may be incorporated in the 
hydraulic line to help to accommodate variations in the material being cut 
and to otherwise aid the clamping action. By holding the material firmly 
between the three rollers, several desirable results are achieved. First, 
the material 10 is held firmly to allow for accurate, precise cutting of 
the material with the saw blades. For example, the surfaces produced as a 
result of the cutting operation can be precisely controlled in spacing, 
smoothness and flatness. The firm clamping action also enhances the 
operation of the grooving of the rollers as will be more fully described 
to maintain driving of the material in rotation and to maintain the 
position of the material from axial displacement after the cutting has 
been initiated. 
Parallelism between at least two of the three rollers 11-13 is highly 
desirable, and the strength and rigidity of the first frame member 14 
contributes to this parallelism. Most suitably, the axes of rotation 25 
and 45 of the rollers 11 and 12, respectively, are parallel. As among the 
three rollers, the precise parallelism is most readily assured for the 
rollers 11 and 12 which are mounted more directly to the first frame 
member than is the third roller 13. Provisions for aligning the rollers 11 
and 12 are desirable, such as by the adjustment of the relative positions 
of the side plates 33 and 34 to align the roller 12 to be parallel with 
the roller 11. 
Roller 13 may suitably be maintained parallel with the rollers 11 and 12, 
or in certain cases may preferably be non-parallel with the rollers 11 and 
12. For example, for material 10 which is slightly tapered to one end or 
which is non-uniform in other respects, it may be desirable to provide for 
one of the three rollers to adapt to this non-uniformity. In the case of a 
taper, for example, the maintaining of parallelism between rollers 11, 12 
and 13 and the application of pressure in this configuration will tend to 
shift the tapered material in the direction of the larger diameter. For a 
very slight taper or other discrepancy in the exterior surface of the 
material 10, it is desirable to have one of the rollers positionable to 
account for this non-uniformity and to thereby maintain an even contact 
and pressure against the surface of the material 10. 
This may be accomplished, for example, by permitting the roller 13 to move 
out of parallelism with the rollers 11 and 12 by a variety of known 
methods. For example, the yoke mounting roller 13 to the hydraulic 
cylinder piston may be secured with a pivotable mounting. Alternatively, a 
pair of hydraulic cylinders could be used to mount the roller 13, in which 
case the piston arms from the cylinders may extend at different lengths to 
provide non-parallel positioning of roller 13 with respect to rollers 11 
and 12. For minor variations, "play" in the roller bearings can be 
adequate to permit proper alignment of the rollers to hold and rotate the 
material. As used herein, the term parallel is intended to include 
variations from true parallelism as described above. 
Loading and unloading means are also provided, and the present invention 
greatly simplifies and facilitates these operations. For example, in the 
position of FIG. 1, the first frame 14 is pivoted away from the saw blade 
assembly 15 mounted on the second frame 16. In this position, the second 
roller 12 is pivoted upwardly and to the right in FIG. 1 to be more 
vertically aligned with the roller 11. While the material is displaced 
from the saws, the roller 13 may be placed in the unclamped position to 
permit loading of material to the unit and removal of the cut material 
therefrom. The pivoting of roller 12 to a more vertical alignment with 
roller 11 facilitates this loading and unloading operation since the 
roller is moved from the path of the material if loading and unloading is 
accomplished by a vertical feed system. It is contemplated that the 
spacial orientation of the first and second frames, and of the rollers and 
saw blade assembly mounted thereon, may be substantially varied. For 
example, the second frame and the saw blade assembly could pivot against 
the first frame fixed to a support surface. Also, the positioning could be 
altered to provide for front, rear, bottom or through the side loading 
and/or unloading of material. 
Upon the loading of a new piece of material for cutting with the apparatus 
in the position of FIG. 1, the roller 13 is moved to the first position to 
clamp the rollers against the material. In the clamped position, the 
rollers are capable of driving the material in rotation, and this is 
accomplished by driving at least one of the three rollers with an external 
driving means. Alternatively, two or three of the rollers may be 
positively driven, but it is considered desirable to drive only one of the 
rollers and have the other two rollers operate as idlers to avoid problems 
which will be more fully discussed below. 
With the material 10 being driven in rotation by the rollers, the first 
frame 14 is pivoted relative the second frame to cause the material to 
engage the saw blade assembly, which is also rotated by an outside driving 
means. As the first frame is so pivoted, to the position shown in FIG. 4, 
the roller 12 is moved downwardly and to the left in FIG. 4. While this 
position is not advantageous for simplified loading and unloading of 
material, it is desirable in the aspect that roller 12 is thereby 
positioned to be nearly diametrically opposed from the saws of the saw 
blade assembly to bear the radial components of the force of the saw 
blades against the material as the frames are pivoted with respect to one 
another. 
Drive means are provided to rotate the rollers and to thereby rotate the 
material clamped between the rollers. Although all of the rollers may be 
individually or gang driven, this is not considered to be preferable since 
certain disadvantages result. One disadvantage is the fact that individual 
or gang driving of all of the rollers results in a more complex drive 
system, which is further complicated by the fact that one or two of the 
rollers is adjustable in its position with respect to the third roller. 
Another disadvantage is the fact that it is difficult to precisely 
coordinate the surface speeds of each of the rollers and this is further 
complicated by the use of different or changeable roller sizes. Differing 
surface speeds of the rollers are undesirable since such will cause 
slippage and tend to disrupt the clamping action and the evenness of the 
sawing operation. These disadvantages are overcome by the present 
invention. 
In the preferred embodiment, axial grooves 124 (FIG. 2) are provided on the 
surface of the drive roller to produce an increased gripping action of the 
roller against the surface of the material 10 to be cut. It has been found 
that the provision of such axial grooves 124 will permit the driving of 
only one of the rollers to produce the desired rotation of the material to 
be cut. The gripping action of these axial grooves is enhanced by the 
amount of pressure applied by the other rollers to force the material 
against this drive roller. 
It is preferred that the drive roller be the roller 11 located to rotate 
about the same axis 25 as the pivoting axis for the relative movement of 
the first and second frames. In this manner, the roller to be driven is 
fixed relative the saw blade assembly, thus permitting the driving of one 
from the other. Further, the roller 11 is fixed with respect to both the 
first and second frames, thus facilitating the driving of this roller from 
an external source mounted in a fixed position relative either of the 
first or second frames. Most suitably, the external power source is 
mounted in a position fixed with respect to the outside frame, which in 
the disclosed embodiment is the second frame 16. Again this permits the 
same source to drive the saw blade assembly either through a separate 
connection or through a geared connection between the saw blade assembly 
and the first roller, as will be further described. 
The use of the axial grooves similarly has been found to greatly simplify 
the device in that provisions for separate driving of the other rollers or 
for ganging together of the rollers is eliminated. Also, only one of the 
rollers can be maintained in a fixed position relative both the first and 
second frames, since the frames pivot with respect to one another. The 
ability to drive only one of the rollers therefore further simplifies the 
positioning and connection of this external drive source to the driven 
roller. 
As shown in the drawings, a further advantage is achieved by having the 
roller 11 operate as the drive roller and by having the movable roller 13 
positioned to firmly force the material 10 against the drive roller. In 
this manner, the action of the axial grooves to grip the material 10 to 
drive it in rotation is enhanced by the pressure applied by roller 13 to 
press the material 10 and drive roller 11 together. It is recognized, 
however, that it is also desirable to locate the three rollers to be 
spaced about the material 10 to facilitate the clamping action, with a 
configuration approximating an equiradial spacing being particularly 
desirable in this respect. Thus, there is a balancing of the desirability 
for maximizing the clamping action with the desirability for providing a 
firm engagement between the material and the drive roller. 
Saw blade assembly 15 is mounted with bearing means to the second frame 16 
to be rotatable about an axis 59 parallel with axis 25. The saw blade 
assembly comprises a shaft 60 having a reduced end 61 received within 
bearing 62 (FIG. 6) mounted within plate 21 of second frame 16. Bolt 63 in 
plate 21 retains bearing 62 therein. Shaft 60 includes adjacent its other 
end an enlarged cylindrical portion 64 which is received within bearing 
cartridge 65 mounted within plate 22 of second frame 16. Bearing cartridge 
65 includes a mounting collar 66 through which set screws 67 are received 
and engage cylindrical portion 64 of shaft 60 to secure the bearing 
cartridge thereto. A retaining bar 68 is secured with bolts 69 to the 
exterior surface of plate 22 to retain bearing cartridge 64 therein. 
A spacer sleeve 70 is received on shaft 60 adjacent the enlarged 
cylindrical portion 64. Several saws 71 and spacers 72 are alternately 
received on the shaft and a second sleeve spacer 73 is received on the 
shaft. Shaft 60 defines a key way 74 and the spacers, spacer sleeves and 
saw blades define complementary key ways and a key is received therein in 
customary fashion. The saws 71 are rigidly secured to the shaft by 
operation of the keyway and the spacers and sleeves 70, 72 and 73, and 
will thereby rotate with shaft 60. Shaft 60 includes a threaded portion 
adjacent the end 61 and a nut 75 is received thereon to secure the saw 
blades and spacers against the enlarged cylindrical portion 64. 
The outside diameter of bearing cartridge 65 is preferably larger than the 
outside diameter of the largest saw blade. In this manner, and due to 
other constructions as described, the saw blade assembly is easily removed 
from the second frame. Upon removal of retaining bar 68, the entire saw 
blade assembly including shaft 60, bearing cartridge 65 and saw blades 71 
may be pulled through the opening in plate 22 in which bearing cartridge 
65 is received. This aspect makes it extremely simple to service the saw 
blade assembly, such as for replacement of worn or broken saw blades or 
for changing of saw blade characteristics. 
The saw blade assembly 15 comprises at least three, and preferably 6 or 
more, disc-shaped saw blades. Such saw blades 71 are securely mounted to 
the shaft 60 to rotate with said shaft. The assembly provides several 
ganged saw blades mounted in parallel spaced relation to rotate about the 
common axis of the shaft. While a particular construction for the saw 
blade assembly 15 is disclosed herein, it is to be understood that 
alternative assemblies of parallel, spaced, ganged saws may suitably be 
used with the present invention. The saw blades may be made from a variety 
of standard materials, and the diameters and thicknesses of the blades and 
the number, size and shape of the saw teeth may be selected for the 
particular cutting conditions and materials. 
It is a feature of the present invention that the use of saw blades, as 
opposed to cut-off tools for example, permit the use of a thinner cutting 
device to minimize waste and thereby conserve material. The saw blades 
used in the present invention may be made at least as thin as one 
sixteenth of an inch, whereas cut-off tools for similar operations would 
typically be at least three-sixteenths of an inch wide. As an example of 
the savings by the present invention, a typical cutting operation is the 
sectioning of tubular stock into rings having a thickness of 0.809 inches. 
The use of a 3/16 inch cut-off tool would produce 240 pieces from a twenty 
foot tubular stock, whereas the present invention would yield 275 pieces, 
an increase of 14.5%. 
To further automate the operation of the present invention, means could be 
provided (not shown) for removal and replacement of the saw blade assembly 
as desired to permit maintenance to be performed on the saw blades 
periodically. For example, a typical double turret unit could be employed 
to periodically release and remove the saw blade assembly in use at a 
given time and to insert a different assembly or the same assembly after 
servicing. Servicing of the assembly would typically include replacement 
of saw blades as required and the regrinding of the blades. 
The desired speed of rotation of the saw blades will depend on the type and 
grade of material being cut, the amount of cutting desired, the feed rate 
of the material against the saw blades, and the nature of the saw blades 
themselves. In a typical embodiment the saw blades are rotated at about 
125 revolutions per minute using 10 high speed saw blades having 60 teeth 
and a thickness of 0.062 inches to cut 1050 steel tubular material having 
a five inch diameter and a thickness of 0.625 inches. The time required to 
cut through the material under these conditions is about three minutes, 
although considerable variations in the cycle time and the speed of the 
saw blades may be used without adversely affecting the results. 
The firm clamping of the material to be cut and the control of feeding the 
material against the saw blades as provided for with this invention 
contribute significantly to the flexibility of the operating parameters. 
The simultaneous rotation of the material and the cutting means provide 
similar advantages. As a result, it is possible to use relatively thin saw 
blades to cut material which would require a cut-off tool of considerably 
larger thickness. The simultaneous rotation of the material and the saw 
blades is significant in that the material is partially cut around its 
circumference before the material is cut through. If this were not the 
case, it would be possible that the cut would not align when the material 
has been turned full circle. This would not only obviously affect the 
precision and smoothness of the cut, but undue strain could result to the 
cutting device if the material is shifting axially or if a grain or other 
property in the material is forcing the cutting device to the side. In 
accordance with the present invention, the cutting around the periphery 
before cutting substantially into the material, or before cutting through 
the material in the case of tubular stock, together with the firm clamping 
and the provision of circumferential grooves on at least one of the 
rollers all combine to minimize conditions which would produce an 
undesirable cut and which would be detrimental to the saw blades and other 
components of the apparatus. 
The present invention operates to generate a cut of the material, as 
opposed to milling the material, and distinct advantages result. In 
accordance with the present invention, a minimum number of teeth are 
present in the cut at any given time, and a maximum pressure per tooth is 
thereby obtained for a given total pressure of the material against the 
saw blades. This reduces the pressure necessary to be applied by the feed 
means to pivot the material against the saw blades. The present invention 
also permits a maximum amount of cooling and lubricating oil into the cut 
and permits increased heat dissipation. Chip production is reduced, 
thereby aiding the cutting operation. In contrast, a milling operation 
whereby the material is cut through while stationary and is then rotated 
in a circle results in low pressure per tooth requiring greater total 
pressure of material against saw blades, reduced cooling and lubrication, 
and higher chip production and resulting disadvantages. 
Drive means are provided for rotating the saw blade assembly. Independent 
drive means may be readily employed, but it is preferred that the same 
drive source be used for both the drive roller and the saw blade assembly. 
As previously noted, certain aspects of the present invention greatly 
enhance the overall operation of the invention. Thus, the ability to have 
only one of the three rollers positively driven by an external source 
simplifies the roller and drive mechanisms and reduces power consumption. 
Similarly, the provision of only one driven roller which has the same 
rotational axis as the pivot axis for the first and second frame members 
greatly simplifies the driving of the saw blade assembly. Since the first 
and second frames pivot about the axis of the drive roller 11, the saw 
blade assembly is in a fixed position relative the drive roller regardless 
of the pivoted position of the frames. It is therefore very simple to 
drive the saw blade assembly and the drive roller with the same external 
source. 
In a preferred embodiment, a gear 76 is secured to the reduced end 77 of 
first roller shaft 26 by a bolt 78. Gear 76 meshes with gear 79 mounted to 
the saw blade assembly shaft 60 by a bolt 80 to provide a driving 
connection therebetween. Either of these shafts may be driven by an 
external source and the meshed gears will consequently result in a driving 
of the other shaft. Similarly, the external drive source may be applied 
directly to one of the gears 76 and 79, or may be applied to both gears, 
in which case the intermeshing of gears 76 and 79 would not be required. 
Due to the fixed relative positioning of the shafts 26 and 60, the 
combined driving of the drive roller 11 and the saw blade assembly is 
readily accomplished. 
It is preferable, as shown, to drive the shafts by the direct driving of 
one of the shafts. In order to obtain the advantage of ready removal of 
the saw blade assembly, it is desirable to drive the shaft 26 of the drive 
roller 11. Shaft 26 extends through plates 17 and 21 and includes a drive 
portion 81 having a keyway 82 (FIG. 5) defined therein. Drive portion 81 
is received within and keyed to a gear reducer 83 in standard fashion. 
Gear reducer 83 is secured with bolts 84 to a mounting bracket 85 (FIG. 
8), which is in turn secured with bolts 86 to second frame plate 21. 
Hydraulic motor 87 is also mounted to plate 21 and is connected with gear 
reducer 83 to drive shaft 26. The hydraulic motor is connected through 
hydraulic line 88 to a suitable source of hydraulic fluid. Alternatively, 
an electric motor could of course be used, and direct drive or coupled 
drive other than through a gear reducer could be employed. 
The simplicity of the present invention and its operation is reflected in 
the simplicity of the preferred controls. For a given operating 
requirement, the operation is fully automatable, with the usual exceptions 
for maintenance and supervision. In addition, specific functions of the 
apparatus may desirably be manually controlled. A control panel could 
include on/off switches for the hydraulic systems, sawing systems and 
cooling systems. In addition, a manual/automatic switch would likely be 
provided. Specific manual switches are desirable for clamping, unclamping, 
and pivoting the material to and from the saw blades. Additional controls 
as desired may be provided, and additional system components may call for 
corresponding control devices. 
As in other types of cutting operations, means are provided for cooling the 
saw blades and material during the cutting operation and for cleaning the 
cutting area. The apparatus is mounted within a pan 89 which includes a 
drain 90 connected to a drain pipe 91. Feed pipe 120 is secured to the 
base plate 24 of the second frame 16 and mounted thereon is a nozzle 121. 
Feed pipe 120 is connected through hose 122 to a suitable source of fluid 
which is pumped through the feed pipe and nozzle under pressure. The fluid 
is directed by nozzle 121 against the surface of the material being cut at 
the location of the cutting. This fluid operates to lubricate and cool the 
saw blades and the material and also to cleanse the cutting area, 
particularly the interior of the cut grooves. A high sulfur base, black 
cutting oil is preferred. This fluid falls onto the base plate and flows 
over the base plate to the screen 123 mounted on the floor of the pan 89. 
The particles of material produced by the cutting are collected on the 
screen and the fluid passes therethrough to the pan and into the drain 
pipe. 
Means are also provided for further cleaning this fluid to remove the 
particles produced during the cutting operation. A magnetic separator (not 
shown) may be used in appropriate circumstances to remove certain metal 
particles from the fluid. Other filtering means may be employed as is well 
recognized in the art for preparing such fluids for recycle. The 
refurbished fluid is returned to a reservoir from which it is pumped to 
the hose 94 and subsequent components. Alternatively to the construction 
shown, a suitable opening in the base plate or other provision in the 
construction of the apparatus may be employed to permit the fluid and 
particles to drop directly into a receptacle from which they are removed 
for filtering or the like. The latter construction facilitates removal of 
the particles since all of the fluid and particles are received in one 
place, rather than using the screen as shown. However, the screen approach 
is suitable particularly in operations where personnel would be present to 
manually clean the screen, thus permitting a more simplified construction 
of the remainder of the apparatus. 
In the operation of the present invention, the saw blade assembly and the 
material to be cut, and therefore the rollers holding the material, are 
simultaneously rotated prior to and during the cutting operation. The saw 
blade assembly and the rollers could be independently driven and provision 
made for controlling the driving of the two to provide simultaneous 
rotation of the saw blades and the material during cutting. By the 
construction of the preferred embodiment described herein, the coupled 
driving of the saw blade assembly and the drive roller results in the 
simultaneous rotation during cutting in a simple and direct manner which 
also achieves the other advantages previously described. 
The relative surface speeds of the saw blades and of the material to be 
cut, and therefore of the drive and other rollers, may be varied within 
desired ranges. The desired relative speeds will vary according to the 
material being cut, the saw blade configurations and composition, and 
perhaps other factors such as the required precision or other parameters 
for the cuts. With independent driving of the saw blade assembly and the 
drive roller the variations in relative speeds can be achieved by varying 
the separate drives. In the preferred embodiment, this variation can be 
readily obtained by corresponding variation in the respective sizes of 
gears 76 and 79. 
The saw blades are rotated to have the portions of the saw blades adjacent 
the material being cut move in the direction of the drive roller. In 
general, it is considered advantageous to have the portion of the saw 
blades at the material being cut move toward the stationary rollers rather 
than at the clamping roller which is held in position by the hydraulic 
cylinder or other pressuring device. If the saw blades rotate in the 
opposite direction, corresponding to counterclockwise in FIG. 4, then the 
saw blades tend to resist the action of the clamping roller. Under such 
conditions, the force of the saw blades may be sufficient to cause 
slippage of the material with respect to the rollers, particularly the 
drive roller, and chattering may occur. This result could be avoided by 
providing sufficient pressure by the clamping roller. However, it is 
preferred that the saw blades simply be rotated in the opposite direction, 
clockwise in FIG. 4, thereby tending to force the material against the 
stationary rollers. This condition promotes clamping of the material and 
good contact between the material and the drive roller to assure even 
rotation of the material. 
The material and the saw blades are simultaneously rotated such that the 
adjacent surfaces upon contact are moving in opposite directions. In FIG. 
4, for example, it is preferred that the saw blades rotate in a clockwise 
direction, and that the material to be cut also rotate in the clockwise 
direction. Consequently, the three rollers will be rotating in the 
counterclockwise direction in FIG. 4. Since the saw blades and rollers 
rotate in opposite directions, the interconnection of the drive roller 
shaft and the saw blade assembly is very simple. A direct coupling of the 
two with meshed gears will produce the proper relative rotations of the 
two, thus further facilitating the using of one shaft and drive means to 
drive the other shaft. 
The relative surface speeds of the drive roller to the saw blade assembly 
are preferably from about 20 to 1 to about 1 to 20, and most preferably 
from about 3 to 1 to about 1 to 3. For example, a relative surface speed 
of the drive roller to the saw blade assembly of 20 to 1 would mean that 
the surface of the drive roller would move at a rate 20 times greater than 
the rate of movement of the edges of the saw blades. Milling operations 
use surface feeds in the range of 40-50 surface feet per minute. In 
contrast, the present invention may use a wide range of surface feeds, 
particularly in the higher ranges typical for high speed saws. The surface 
feeds vary with the factors previously indicated, and preferably range 
from about 100 to about 1000 surface feet per minute, more preferably from 
about 150 to about 300. In a typical embodiment, four inch diameter saw 
blades and a 5.25 inch diameter drive roller were used rotating at 100 and 
87 RPM's, respectively. The result is a rate for the saw blades and drive 
roller of 104.7 and 119.6 surface feet per minute, respectively, or a 
total, effective feed of 224.2 surface feet per minute. In a preferred 
embodiment using the same size saw blades and roller at 125 and 50 RPM's, 
respectively, surface feed rates of 130.9 and 68.7, for a total effective 
feed rate of 199.6 surface feet per minute is achieved. 
The rollers of the present invention preferably have cylindrical exterior 
surfaces which contact the material to be cut when clamped therebetween. 
Similarly, the present invention is intended for use in the cutting of 
material having an exterior cylindrical surface. For the purposes herein, 
the term cylindrical is used both in the strict geometric sense, and also 
to include shapes which are approximately cylindrical. It will be 
appreciated that substantial variation from a strictly cylindrical shape 
for either the rollers or the material to be cut will interfere with the 
optimum operation of the present invention. At the same time, however, 
minor variations will naturally exist in the rollers, and probably moreso 
in the material being cut. Minor variations in the outer diameter of tube 
stock, for example, are common and are intended to fall within the meaning 
of the term cylindrical as used herein. As a further example, piston rings 
and the stock from which they are cut are also non-circular in cross 
section, but can be properly produced by the present invention. Such 
material is specifically intended to be included within the term 
cylindrical as used herein, and the operation of the present invention 
with such material is intended to be covered hereby. 
Means may be included in the present invention to accomodate differing 
degrees of non-uniformities or other variations in the material to be cut. 
As previously discussed, one of the rollers, preferably the one which 
clamps the material against the other rollers, may be mounted to deviate 
from parallelism with the other rollers to account for certain material 
non-uniformities, such as a slightly tapered external surface. For other 
non-uniformities in the outer surface of the material, such as a non-round 
surface as occurs for piston ring stock, additional means may be provided 
to accomodate this. In the preferred embodiment, the third roller 13 is 
mounted to a hydraulic cylinder which is secured to the first frame 
member. The hydraulic cylinder applies pressure to clamp the three rollers 
against the material to be cut. To accomodate a non-round or otherwise 
non-uniform material in this embodiment, the pressure of the hydraulic 
cylinder is adjusted to yield to the varying external surface of the 
material being cut. The cylinder thereby permits the roller 13 to move to 
the extent necessary to accomodate the outside surface of the material, 
while maintaining the requisite clamping pressure to firmly hold the 
material within the three rollers. Other means could similarly be 
provided, such as the use of a spring mounting of one or more of the 
rollers to permit yielding of the position of the roller to accomodate 
variations in the surface of the material to be cut. It is another aspect 
of the provision by this invention for driving only one of the rollers 
that accomodation of such material can be easily achieved without 
conflicting with complex drive mechanisms. 
As shown somewhat schematically in FIG. 1, a feed means 92 is provided for 
moving the first frame 14 relative the second frame 15 by pivoting about 
the axis 25. In a first position, as shown in FIG. 1, the material to be 
cut is displaced from the saw blades. In this first position, the material 
is loaded into or unloaded from the rollers 11-13. Once a length of 
material to be cut is loaded into the rollers and clamped therebetween, 
the drive roller, and therefore the material, is rotated and the saw blade 
assembly is also rotated by the respective drive means. The feed means 
then operates to provide controlled movement of the first frame relative 
the second frame to a second position, as shown in FIG. 4, in which the 
saw blades engage and cut the material. 
A preferred embodiment for the feed means is shown particularly in FIGS. 
9-11. A ball screw unit 93 is mounted to the second frame and includes a 
ball screw 94 attached to the first frame. Mounting plates 95 and 96 are 
attached with bolts 97 to the second frame plates 21 and 22, respectively. 
Bracket 98 includes opposed posts 99 which are received respectively 
within bushings 100 and 101 secured within aligned apertures in the 
mounting plates 95 and 96. Bracket 98 and therefore the ball screw unit 93 
which is mounted thereon are thereby pivotable about the axis of posts 99. 
Ball screw 94 is secured at its lower end to a clevis 102 which is pinned 
thereon. A yoke 103 including arms 104 and 105 is secured with bolts to 
the rear surface of cross member 19. Pin 106 is secured within apertures 
in the arms 104 and 105 and extends through an aperture in clevis 102 to 
provide a pivotal connection between the ball screw 94 and the first 
frame. 
Ball screw unit 93 includes a variable speed hydraulic motor 107 connected 
through hydraulic lines 108 and 109 to a suitable fluid source. The motor 
107 is operable to drive a hollow shaft worm gear reducer which drives the 
ball screw nut in rotation to cause the ball screw to displace axially 
with respect to the ball screw unit. The axial displacement of the ball 
screw produces a corresponding relative movement between the points of 
connection of the ball screw to the first and second frames. As the ball 
screw is drawn upwardly relative the ball screw unit in FIG. 9, for 
example, the rear end of the first frame is moved upwardly, causing the 
first and second frames to pivot in the direction toward the first 
position of FIG. 1. Conversely, as the ball screw nut is rotated in the 
opposite direction to force the ball screw to displace downwardly in FIG. 
9, the first frame is pivoted downwardly in the direction of the second 
position shown in FIG. 4. 
The provision of the two pivot points at the connections of the ball screw 
and unit to the first and second frames accounts for the pivoting movement 
which results between the frames upon displacement of the ball screw. 
Alternative feed means for providing controlled pivoting movement of the 
first and second frames may be used and are contemplated by this 
invention. For example, a similar ball screw unit could be employed in 
which the ball screw is rotated and the nut is displaced along the screw. 
A hydraulic cylinder, such as shown in FIG. 1, or other variety of 
movement means may be used as the feed means as well. 
It is highly desirable that the feed means employed be capable of well 
controlled relative movement between the first and second frames. The rate 
and evenness of the pivoting movement between the frames will affect the 
cutting operation. Assuming other parameters to be fixed, there will be 
preferred rates of feed and desired evenness of feed of the material 
against the saw blades. If the feed rate is too slow then the apparatus 
may be operated inefficiently, whereas a feed rate which is too fast may 
produce a less favorable cut and may result in damage to the material 
being cut, the saw blades, and other portions of the apparatus. A feed 
means such as a ball screw unit provides the opportunity for a very even 
and controllable rate of feed, and is therefore considered preferable. 
Limit means are provided for controlling the movement of the ball screw 94, 
and therefore of the relative pivoting movement between the first and 
second frames. Such limit means may assume a variety of known control 
means. As shown in FIG. 11, a mounting rod 110 is secured to the upper end 
of the ball screw 94 and carries a pair of limit switch trips 111 and 112. 
A second rod 113 is mounted to the housing of the ball screw unit 93. 
Secured to the rod 113 are a pair of limit switches 114 and 115 connected 
through electrical lines 116 and 117, respectively, to a suitable fluid 
source and control unit. 
Upon downward movement of the ball screw, and therefore of the first frame, 
arm 118 of the limit switch 114 will contact the trip 111 and signal 
stoppage of the downward movement of the screw, corresponding to 
completion of the cutting operation. The ball screw subsequently is moved 
upwardly relative the ball screw unit to move the first frame to the 
second position with the saw blades displaced from the material to be cut. 
Upon such upward movement, arm 119 of the limit switch 115 will engage the 
trip 112 and signal stoppage of the upward movement. In this manner, the 
pivoting of the frames of the apparatus is cycled through each cutting 
operation. 
In the cutting cycle of the present invention, a length of material having 
an exterior cylindrical surface is loaded into an apparatus of the 
described type. The third roller 13 is maintained in the second position 
displaced from the rollers 11 and 12 while the material is inserted 
between the three rollers. The clamp and release means then operates to 
move the third roller 13 to the first position to clamp the three rollers 
against the exterior cylindrical surface of the material to be cut. 
Sufficient pressure is applied by the rollers to firmly engage the 
material, and to provide even rotation of the material upon being driven 
by the drive roller 11. The respective drive means initiate simultaneous 
rotation of the saw blade assembly and of the drive roller and the feed 
means pivots the first frame relative the second frame from the second 
position to the first position. 
As the pivoting of the frames feeds the material against the saw blades, 
the material and saw blades are simultaneously rotating and initially the 
cutting forms several circumferential grooves in the material. With 
further pivoting of the frames toward the first position, the grooves 
deepen until, in the case of tubular material, the cut passes completely 
through the material separating it into several ring-shaped pieces. In the 
event that the cut passes completely through the material, the three 
rollers will continue to clamp each of the pieces of material in the 
position originally held before cutting. 
The completion of the cutting operation is signaled by the limit means as 
the trip 111 engages arm 118 of the limit switch 114. Upon completion of 
cutting, the feed means operates to pivot the first frame to the first 
position, thus separating the saw blades from the material. The clamp and 
release means moves the third roller 13 to the second position displaced 
from the other rollers, to permit unloading of the cut material from the 
apparatus. The cut material, whether it be several ring-shaped pieces or 
one integral piece, is then unloaded from the apparatus and a new length 
of material is loaded for the next cutting cycle. 
It is preferred that the rotation of the saw blade assembly and of the 
rollers be stopped upon completion of the cutting operation, and the 
pivoting of the first frame away from the saw blades occur with the saw 
blades and rollers stopped. In this condition, the third roller can be 
operated to release the material from the clamped condition and to move 
out of the way in preparation for unloading of the cut material, without 
interference by the saw blade assembly and drive roller rotations. In this 
manner, the third roller is out of the way and the material may be 
immediately unloaded once the first frame has pivoted sufficiently toward 
the second position displaced from the saw blade assembly. Other 
provisions may be made to speed and otherwise facilitate the loading and 
unloading portions of the cycle. For example, rapid advance and withdrawal 
of the third roller and of the first frame member may be utilized to 
reduce the time occupied by these movements. 
Particular components of the present apparatus may be desirably modified 
for certain cutting operations. As discussed, variations in the saw blades 
in terms of size, configuration and material may be desired. Further, the 
diameters of the saw blades may be varied as well as the spacing of the 
blades. For example, combinations of different diameter saw blades could 
be employed to cut into a material in differing depths, or to form an 
annular shoulder at the location where cutting is going to proceed 
completely through tubular material. The spacing between adjacent saw 
blades may be varied, and two or more saw blades may be positioned 
together to provide a different cut of the material. 
Similarly, the size and configuration of the three rollers may be varied to 
suit particular cutting operations. In one aspect, it is preferable that 
the drive roller include an external surface defining several axial 
grooves 124, preferably of a depth of about 0.003 inches, to enhance 
gripping of the material to drive it in rotation upon rotation of the 
drive roller. In another aspect, it is preferable that at least one of the 
rollers include several circumferential grooves 125 which operate to 
enhance gripping of the material to resist axial movement of the material 
relative the rollers. Particularly when the material has a non-uniform 
diameter or has a surface grain, there may be a tendency for the material 
to shift axially along the rollers, thus interfering with the accuracy and 
precision of the cuts. The circumferential grooves, which preferably have 
a depth of about 0.003 inches, have been found to substantially prevent 
this movement, producing a more precise, flatter cut of the material. 
The configuration of the rollers may be varied in other respects as well. 
The rollers preferably have a continuous, cylindrical surface for the full 
extent of the location of saw blades, with the exception of the relatively 
narrow and shallow grooves previously described. Particular other 
variations may also be desirable for certain cutting operations. For 
example, the present invention is useful in cutting inner bearing races 
from machined stock. In this operation, an indexing ridge on one of the 
rollers may be desirable to locate with precision the material with 
respect to the location of the saw blades. For cutting operations 
performed on tubular or bar stock, this locating with respect to the saw 
blades is of lesser importance, although an end stop or other means may be 
employed to locate such material in the cutting space. The use of such a 
locator in these circumstances may further minimize waste of material 
since significant end pieces of improper size may be avoided. It is a 
considerable advantage of the present invention that material is 
conserved, particularly over prior art devices utilizing arbors which 
leave a substantial end piece which can not otherwise be economically 
salvaged. The present invention may be adapted for cutting these pieces, 
as well as for operating on substantial lengths of material in which case 
no such pieces are generated. 
An aspect of the present invention is the placement of the pivot point for 
the two frames relatively close to the location of the saw blade assembly. 
This placement and the relatively distant location of the feeds means 
provides for a highly controllable feeding operation. First, the lever arm 
advantage obtained by this configuration enables more efficient use of 
force applied to feed the material against the saw blades. Second, the 
lever arm advantage tends to minimize and dampen the variations in applied 
force from the feed means and in resistive force of the material as it is 
being cut. Third, the distance which the material moves relative the saw 
blades is only a fraction of the corresponding distance which the ends of 
the frames move in pivoting. Therefore, variations in rates of movement of 
the feed means components, and therefore of the rear ends of the first and 
second frames connected with the feed means, result in only fractional 
variations in the rates of movement of the material against the saw 
blades. This enables a more even and precise control of the feeding of the 
material against the saw blades. For example, a variation of one inch per 
minute in displacement of the ends of the first and second frame members 
would only result in a variation of perhaps one-tenth of an inch per 
minute in feeding of the material against the saw blades. 
The proximity of the pivot axis for the first and second frames to the saw 
blade assembly also contributes to the accuracy and precision of the cuts 
by the saw blades. The components of an apparatus necessarily have limits 
as to tolerance of sizes, and a certain amount of "play" in the moving 
components in particular will result. Also, wear of the parts will 
contribute to the play which results. By locating the pivoting axis for 
the frames proximate to the saw blade assembly, the affect of such play is 
minimized. This factor is comparable to the minimization of rate variation 
previously discussed. For example, assume that there is play in the drive 
roller 11 such as would permit or create a deviation at the roller of one 
hundredth of an inch. The resulting deviation at the rear ends of the 
first and second frames may be one tenth of an inch, whereas the deviation 
at the location of cutting by the saw blade assembly would perhaps be only 
two hundredths of an inch. Thus, it will be appreciated that the farther 
the saw blade assembly is located from the pivoting axis for the first and 
second frames, the more pronounced will be the effect of deviations such 
as result from "play" in the bearings or other components involved in the 
pivoting action.