US3741193A

US3741193A - Slate trimming machine

Info

Publication number: US3741193A
Application number: US00719571A
Authority: US
Inventors: Sueur J Le; E Blauvelt
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-04-08
Filing date: 1968-04-08
Publication date: 1973-06-26
Anticipated expiration: 1990-06-26

Abstract

Method and machine for trimming slate chips to predetermined size for use as shingles, etc. The generally planar chips are fed to and between contacting, yieldingly mounted runs of upper and lower pairs of power-driven conveyor belts and, while under translation by and between the belt runs, move between two opposite, axially spaced pairs of circular trimming blades. Each pair consists of parallel, contiguous upper and lower blades, respectively, having beveled peripheral edges and which are slightly axially offset and have their contiguous peripheral portions slightly overlapping. The chips are thus simultaneously trimmed along two opposite parallel edges, to have the same desirable appearance as hand-trimmed shingles.

Description

United States Patent 1 Le Sueur et al.

[11] 3,741,193 1 June 26, 1973 Primary Examiner-Harold D. Whitehead Attorney-Elizabeth Newton Dew [5 7] ABSTRACT Method and machine for trimming slate chips to prede termined size for use as shingles, etc. The generally planar chips are fed to and between contacting, yieldingly mounted runs of upper and lower pairs of power-driven conveyor belts and, while under translation by and between the belt runs, move between two opposite, axially spaced pairs of circular trimming blades. Each pair consists of parallel, contiguous upper and lower blades, respectively, having beveled peripheral edges and which are slightly axially offset and have their contiguous peripheral portions slightly overlapping. The chips are thus simultaneously trimmed along two opposite parallel edges, to have the same desirable appearance as hand-trimmed shingles.

8 Claims, 7 Drawing Figures SLATE TRIMMING MACHINE [76] Inventors: Joel M. Le Sueur, Arvonia,

23004; Everet M. Blauvelt, Bremo Bluff, both of Va.

[22] Filed: Apr. 8, 1968 [21] Appl. No.: 719,571

[52] US. Cl. 125/23 T, 125/25 [51] Int. Cl B28d 1/32 [58] Field of Search 125/23, 25; 143/40; 83/490 [56] References Cited UNITED STATES PATENTS 518,655 4/1894 Stow 143/40 2,731,961 1/1956 Ponseele 125/23 3,347,289 10/1967 Kotesovec 143/40 FOREIGN PATENTS OR APPLICATIONS 76,830 5/1950 Norway 125/23 IO) C SHEET 2 OF 4 'J $8 mr N U 5 m5 u o u N w: M d T, M 0Q 0 y 9 J o w J Q m. mm 6 o R 0 -20 :1 J

Everet M. Blouvelt M far ATTORNEY PMENIED JUN 26 I975 SHEET 3 BF 4 o l3b F I G .6

INVENTORS Joel M. LeSueur& Everet M Blouvelt BY %,-M y; 64/

ATTORNEY PATENTEDJUIIZS I973 v SHEEI '4 0F 4 A m G J v a a Z 4 4 IINVENTORS Joel M. LeSueur 8 Everet M. Bluuvelt ATTORNEY SLATE TRIMMING MACHINE This invention relates to a method and machine for trimming slate chips to commercial sizes for use as shingles.

It is the chief object of the invention to provide a machine which trims slate chips rapidly, accurately, efficiently, and with a minimum of waste.

A secondary object is to provide a machine as aforesaid which trims the chips to produce shingles having edges which are identical in appearance with handtrimmed shingles.

Another object is to provide a machine of the type mentioned, which is relatively simple to construct and operate, positive and reliable in operation, readily serviced as required, and a general advance in the art of producing slate shingles.

A further object is to provide a machine as aforesaid, wherein the trimming knives or blades are readily removed for sharpening and replacement, with a minimum of down time.

Still another object is to provide a novel method of trimming slate chips to commercial sizes for use as shingles having the same desirable appearance as handtrimmed shingles.

Yet another object is to provide a machine which is quickly and easily adjusted to vary the transverse dimension of the shingles being trimmed.

Another object is to provide a machine which trims the chips to any selected one of a number of standard commercial widths, reduces breakage to a minimum, and results in reduced costs of production of slate shingles.

Other objects and advantages of the invention will become apparent to those skilled in the art, after a study of the following detailed description in connection with the accompanying drawing.

In the drawing:

FIG. 1 is a sectional side elevation taken about in a plane identified by line 1 1, FIG. 3, looking in the direction of the arrows;

FIG. 2 is a side elevation looking from right to left, FIG. 3;

FIG. 3 is a view looking down on the machine, parts being omitted to better show the lower conveyor belts and the means by which the trimming blade assemblies are adjusted transversely of the frame, for selection of the size of the shingles being produced;

FIG. 4 is a perspective view of the delivery end of the machine, showing in particular the speed-reducing drive means for the lower conveyor belts;

FIG. 5 is a detail view to an enlarged scale, of one of the two identical pairs of trimming blades, showing their relative disposition in operation;

FIG. 6 is a detail view to an enlarged scale, of one of the plurality of guide pulleys, a number of which are used to guide and support the contacting runs of the conveyor belts; and

FIG. 7 is a side elevation of one trimming blade assembly, showing the means by which the assembly is counterbalanced in desired position.

In general, the machine consists of a rigid frame mounting in transversely spaced parallel relation, an upper pair and a lower pair of endless conveyor belts, to have horizontal adjacent runs in yielding contact. At least the lower pair of belts is power driven. At each side of the contacting runs of the upper and lower pairs of belts there is mounted for free rotation, a respective one of two pairs of trimming blades. The blades are circular and have their peripheries beveled or chamfered. The axes of rotation of the blades of each pair are in fixed relation, such that the trimming edges are slightly axially offset, and their contiguous peripheral portions slightly overlap. The lower blade of each pair is offset inwardly, that is, toward the conveyor belts, with respect to the upper blade and, in effect, forms a support for the portion of the chip being instantaneously trimmed. The upper blade acts to trim or shear off the rough edge of the chip and, in cooperation with the lower blade of that pair, to sever the chip along a generally straight line which, however, has the same desirable appearance as a hand-trimmed shingle.

The blades of each pair rotate freely on axes one of which is above and the other below, the plane of the chip as it is translated by and between the contiguous runs of the upper and lower belt pairs. These axes are parallel, and parallel with the plane of the chip, normal to its direction of translation.

The contiguous or contacting runs of the belts are yieldingly urged together so that they allow the chip to pass freely, while positively gripping and moving it through the machine until trimming is completed. Each pair of blades is adjustable as a unit in the direction of their axes, and releasably fixed in adjusted position so that the spacing of the pairs determines the dimension of the shingles being produced.

Referring in detail to the drawing, a parallelepipedal frame generally identified at 1, is composed of angle bars welded or otherwise rigidly united. The frame may consist mainly of four uprights, two of which are identified at 2 and 3, FIGS. 1 and 2, interconnected by vertically spaced longitudinals 4 and 5, and transverse members two lower ones of which are identified at 6 and 7, FIG. 3. The lower of the two longitudinals at the side remote from the one appearing in FIGS. 1 and 2, is identified at 8, FIG. 3.

At its left side as viewed upon FIG. 2, the frame is provided with an extension generally identified at 9. Right and left horizontal, horizontally spaced tracks are fixed to this extension. In the figure, the rightward of these tracks appears at 9a. The tracks conjointly support by means of rollers such as 9b and 9c, a slide 10, for guided horizontal translation in the direction of movement of a chip as it is fed to and between the contacting passes of the conveyor belts. The slide includes a transversely extending, upstanding ledge 10a against which the edge of a chip to be trimmed may abut. Thus, in feeding the machine, slide 10 is withdrawn to the left, FIG. 2, a chip 58 is place upon it with one edge thereof abutting ledge 10a, and the slide and chip are advanced as a unit into the machine until the chip is picked up by the belts.

A horizontal shaft 11, FIGS. 1, 2 and 3, is joumaled in bearings, not shown, carried by brackets 11a, 11b, fixed with and extending from frame I. The shaft has fixed thereon a first pair of axially spaced V-belt pulleys one of which, 12, appears upon FIG. 2. The other is indicated at 12a, FIG. 3. Similarly, brackets 13a, 13b fixed to and extending from the frame at its opposite side, carry'bearingsjoumaling a shaft 13. A second pair of V-

belt pulleys

14, 14a are fixed to this shaft in axially spaced relation therealong, upon opposite sides of bracket 13b. Each pulley of one shaft is in the same vertical plane as a corresponding pulley of the other shaft and forms a pair therewith. Each pair of pulleys guides a respective one of two V-belts. One of these is identified at 15, FIG. 1, as passing about pulley pair l2'and 14. See also FIG. 3 where the other belt 15a is shown entrained about

pulleys

12a and 14a. As will be clear from inspection of FIGS. 3 and 6, the belts are relatively wide, for example 2 inches, and have flat outer surfaces and spaced parallel V-ridges integral with their inner surfaces.

The means for driving shaft 13 and the two pulleys thereon, at reduced speed, are shown upon FIGS. 1, 2 and 4; and from the latter figure it is noted that such means are carried by a supplemental framework made up of angle bars fixed to and mounted upon frame 1 at the left side thereof, facing from the left, FIG. 1. A motor 17 is bolted to a plate carried by the upper longitudinals of the aforesaid supplemental frame, and has a pulley 17a which drives a V-belt 18. The belt passes about a pulley 19 fixed to shaft 20. The shaft carries a smaller pulley 22 and is journaled in bearings one of which is indicated at 21. A second belt 23 passes about pulley 22 and a larger pulley 24 fixed to shaft 25. One of the two bearings for this shaft is indicated at 26.

A small sprocket 27 is fixed to shaft 25 and drives a chain 28 which passes downwardly to and about sprocket 16, fixed to shaft 13, and upwardly about a tightener pulley or sprocket 29 adjustable mounted upon a convenient part of the frame. Thus, in a way clear from inspection of FIGS. 1, 2 and 4, motor 17 is effective to drive

belts

15 and 15a at reduced speed. The linear speed of these belts may be about l foot per second. I

The upper runs of

belts

15 and 15a are guided in and along a horizontal plane at about the level of slide 10, by a series of idler pulleys each individually and yieldingly urged upwardly. Since these idlers are alike and similarly mounted and urged, a description of one of them is sufficient.

Referring more particularly to the idler pulleys for conveyor belt 15, a longitudinal beam 30 is fixed to and within frame 1 by suitable brackets not shown. Confining attention to the one idler indicated at 31, FIGS. 1, 2 and 6, this item is joumaled on a stub shaft 32 having one end fixed in the distal end of a short arm 33. The other end of this arm is pivoted at 34 to bar 30. In normal position the arm is inclined forwardly and upwardly as shown, and has welded thereto, an abutment 35. A coil spring 36 is generally vertically disposed and has its upper end anchored by any suitable means, to abutment 35, and its lower end smoothly fitting over the reduced upper end of an adjusting screw 37. Bar 30 is conveniently at 90 angle, and screw 37 may be threaded upon an opening in the lower horizontal flange of the bar.

Thus in a manner clear from inspection of FIGS. 1 and 2, screw 37 may be adjusted to vary the force with which spring 36 urges arm 33 about its pivot 34 and,

consequently, the upward force exerted upon the contiguous section of belt 15, by idler 31.

In the model selected for illustration each upper pass or run of each of the lower conveyor belts is provided with five of these idlers like item 31 just described, and as clearly shown upon FIG. 1. The idlers of each series may be uniformly spaced and, of course, extend over a distance sufficient to firmly grip and convey the chip horizontally until it has been trimmed in the manner subsequently described. It will be understood, however, that the number and spacing of these idlers may be varied within limits, without departing from the spirit and scope of the invention. Reference to FIG. 1 shows that the topmost elements of idlers including item 31, conjointly lie in and define a horizontal line which lies somewhat above the line determined by the corresponding elements of

pulleys

12 and 14, so that the upper run of belt moves from pulley l2, upwardly and forwardly to the first of idlers 31, and downwardly and forwardly from the final one of these idlers, to pulley 14. FIG. 6 shows one of these idlers to consist of a single spool with

integral flanges

38, 39, and center flange 40.

' these is shown at 46, FIG. 4, welded to and extending from frame 1. The shaft has conveyor belt pulleys 47, 48 secured to it, in axially spaced relation and upon opposite sides of bracket 46.

Pulleys

45 and 48 are in a common vertical plane and receive and mount upper conveyor belt 50. A second upper conveyor belt 49, FIG. 4, passes about guide pulley 47 and its counterpart pulley, not shown, on shaft 41 at the feed end of the machine, and axially spaced from pulley 45. Thus, lower belt 15 and upper belt have confronting and contacting runs. Likewise

belts

15a and 49 have runs which pass in contact in essentially the same horizontal plane as the contacting runs of

belts

15 and 50.

Belts

49 and 50 are not positively driven, as are the lower belts but, to the contrary, are driven by frictional contact with the respective lower belts, or by a chip passing between the two pairs of belts. Of course, if desired, shaft 44 may also be positively driven like shaft 13, to move

upper belts

49, 50 at the same linear speed as

belts

15, 15a.

Referring more particularly to FIG. 1 for description of the system of guide idlers for belt 50, a longitudinal beam 51 is fixed to and within frame 1, above and in horizontal parallel relation with beam 30. A plurality of guide idlers such as the one identified at 52, are carried by this beam, each through the intermediary of a respective arm 53. From the figure it is noted that the number of upper idlers is equal to the number of lower ones 31, five in the model shown; and that each upper idler is directly over a corresponding idler of the lower assembly.

Since each upper idler is mounted by its arm, in the same manner as has been previously described for the lower assembly, it is sufficient to identify, in connection with idler 52, its arm 53 pivoted at 54 to the vertical flange of 90 angle bar 51, abutment 55 welded to arm 53, coil spring 56 exerting a downward thrust upon the abutment, arm and idler 52, and adjusting screw 57 threaded through a tapped hole in the horizontal flange of beam 51, and adjustable like screw 37, to vary the force exerted by the spring. As is clear from FIG. 1, all of the five idlers of the upper assembly for belt 50, are similarly mounted. Thus, for example, lower and

upper idlers

31 and 52 are yieldingly stressed together and conjointly act to urge the corresponding confronting portions of the belts, into contact.

It will be understood (a) that belts a and 49, FIG. 4, each have a series of idlers like those just described for

belts

15 and 50, similarly spaced therealong, and each mounted like

idlers

31 and 52, to urge the confronting horizontal runs of

belts

15a and 49, into yielding contact; (b) that in the model shown there are five lower idlers like 31, for belt 15a, and five upper idlers, like '52, for belt 49; (c) that each upper idler of belt 49 is directly above a corresponding one of the lower idlers of belt 15a; and (d) that each idler such as 31, for example, of belt 15, is essentially coaxial with its counterpart idler for belt 15a.

Thus, referring to FIG. 3, when a chip as indicated at 58 is placed on slide 10 and advanced to about the position shown, it is gripped by and between the two pairs of belts and positively translated in its own plane, through the machine. Irregularities in the surface of the chip are compensated by yielding of the rollers or idlers, each against the urge of its own spring. At 58a the chip is shown partly trimmed, and at 58b it is shown as passing from the delivery end of the machine, completely trimmed.

Right and-left cutter or trimmer blade assemblies are indicated generally at 60, 61, respectively, FIG. 3. A heavy horizontal shaft 62, FIG. 2, is clamped and fixed to the two rear verticals of the frame 1. One of these verticals is identified at 3, FIGS. 1 and 2. The shaft passes just above the lower runs of the two

upper conveyor belts

49 and 50, FIG. 4, as these belts pass from the final one of the upper idlers, on their way to

respective pulleys

47 and 48.

The right trimming blade assembly generally indicated at 60, FIGS. 2, 3 and 5, comprises a V-shaped mount 63, cut from a metal plate and having at its apex a sleeve 64 welded thereto. This sleeve has a smooth fit on shaft 62 so that it may pivot and slide thereon.

At the distal end of its upper arm, mount 63 carries a stub shaft 65 adjustably fixed in a generally vertical slot 66 formed in and through the arm. A trimming blade 67 is journaled on the free projecting end of this shaft, by an antifriction bearing 68. Referring to FIG. 5, it is noted that the shaft has a reduced end receiving the inner race of the bearing, which is clamped to the blade by four through-bolts such as 69. A nut 70 on the threaded end of the shaft, prevents axial movement, while permitting free rotation of the blade. Since both blades, upper and lower, are mounted in a like manner, each upon its own stub shaft, it is sufficient, still referring to FIG. 5, to identify lower backing blade or stake 64, shaft 71, antifriction bearing 72, one of four through-bolts 73, clamping plate 74 holding bearing 72 to the blade, and nut 75 threaded upon the reduced distal end of the shaft. The

shafts

65 and 75 fixed in the respective arms of V-mount 63, are adjustable. Thus, shaft 65 may be adjusted generally vertically in and along its slot 66. Likewise shaft 71 may be adjusted generally horizontally, by loosening nut 77. In each case, tightening of the nut 76 or 77, as the case may be, fixes the corresponding shaft in adjusted position. Thus the two blades may be relatively adjusted to vary, within limits, (a) their overlap and (b) the relation of the rotational axis of one of them with respect to a vertical plane through the axis of the other. A bar 78, FIG. 2, has its ends welded to the mount adjacent the ends of its arms, for the purpose of rigidifying the assembly.

Referring to FIG. 7, a short metallic strap 79 is welded to mount 63 adjacent to its sleeve 64, and has a lever 80 pivoted to it, at 81. The strap and lever have generally parallel, outwardly extending abutment bars 82 and 83 welded thereto. Bar 83 is slightly bent downwardly out of the plane of the figure, so that the free or distal ends of these bars are vertically superposed. A cup secured to the distal end of bar 82 receives the lower end of coil spring 84. An adjusting screw 85 is threaded through the end of bar 83 and has its end in engagement with the upper end of the spring.

The upper end of lever 80 has a bracket 86 welded thereto. The horizontal portion of this bracket carries a shaft on which a roller 87 is journaled. The roller is so positioned that it may roll on and along the flat vertical face of the top horizontal transverse member 88 forming a part of the machine frame 1.

Thus with spring 84 properly tensioned by adjustment of screw 85, roller 87 engages beam 88 and trimming blade assembly 60 is counterbalanced about the axis of shaft 62 and thus supported in properly adjusted rotational position. This position is such that the overlapping peripheral portions of blades 64 and'67 are at the level of the plane of translation of a chip by and between the contacting runs of the conveyor belts. Further, the construction just described, permits free translation of the assembly 60, on and along shaft 62.

FIG. 5 shows the overlapping and axially offset relation of the blades. While not highly critical, and merely as one example of operative conditions,

blades

64 and 67 may be 8 inches and 10 inches in diameter, respectively. Their confronting plane faces may be axially offset about one-fourth inch and their beveled edges may overlap about one-eighth inch. As shown, the peripheries of the blades are beveled and mounted with their sharpened edges contiguous. The bevel of blade 67 may be about 45 while that of blade 64 is preferably at a smaller angle, say 30. Blade or stake 64 is of heavier stock, about five-sixteenths inch, while blade 67 may be of stock about one-fourth inch thick. Reference to FIG. 2 shows that the axes of the two blades are parallel and essentially vertically superposed, with blade 64 on the inside.

Due to the pivotal mounting of the assembly on and about shaft 62, the blades may play freely upwardly and downwardly during operation, to accomodate surface irregularities of the chip. Blade 64 forms a backing, supporting the lower surface area of that portion of the chip being instantaneously trimmed, while blade 67, in effect, severs the chip along the desired line to form an edge which, when completed, has the same desirable and attractive appearance .as a hand-trimmed shingle. This highly desirable and useful result is believed to be due to the permissible vertical interplay and interaction between the contacting runs of the conveyor belts and the blades, wherein the belt runs may shift slightly vertically to accomodate surface irregularities of the chip, while the blades may freely follow any vertical shift of the chip and thus maintain essentially constant, the severing forces they exert upon the respectively opposite surfaces of the chip. From FIG. 2 it is seen that the plane determined by the axes of

blades

64, 67, passes adjacent the fourth of the idler pairs, upper and lower, counting from the feed end of the machine.

While the machine is highly useful with but one pair of trimming blades, constructed and arranged as just described, it is contemplated to use two trimming blade assemblies operating simultaneously, each on a respective side of the conveyor belt runs, as forexample, in trimming the chip along laterally spaced parallel lines, to form the two side edges of the shingle.

In FIG. 3 a second blade assembly is identified at 61, wherein all parts are mounted and related in the same manner and for the same function as the parts of assembly 60, at the left side of belts a and 49. In the second assembly the lower blade is also on the inner side of its upper blade, that is, between the upper blade and the conveyor belts. The V-shaped mount for the second blade assembly has a sleeve, not shown, like sleeve 64, FIG. 2, which is also rotatably and slidably mounted upon shaft 62.

Means are provided for independently sliding and adjusting each blade assembly on and along shaft 62. Describing such means for assembly 60, a U-shaped bracket 89 (FIG. 3) has its ends clamped to frame 4, to extend generally horizontally from the delivery end of the frame. An adjusting lever 90 is pivoted at 91 to the transverse portion of the bracket, and extends up wardly and rearwardly to terminate at a location for convenient operation near the feed end of the machine. See FIG. 2. Referring to FIG. 3, a lug 92 is fixed to lever 90 between the ends thereof, and is offset outwardly and downwardly. At its free end this lug is pivoted to one end of a link 93, the other end of which is pivotally connected to any suitable fixed part of the V-frame 63, or to its collar 64. Thus as lever 90 turns about its pivot 91, it operates to slide assembly 60 on and along shaft 62. A bar 94 fixed to a convenient part of the frame has notches in its top edge, spaced therealong. Lever 90 is yieldingly urged into downward rotation about shaft 62, as by a spring not shown, and may fit into any selected one of the notches, to thereby releasably hold the trimming blade assembly in a desired position of adjustment along shaft 62.

When a second trimming blade assembly is used or provided, as indicated at 61, FIG. 3, this also is equipped with an adjusting lever 95. Since this lever is mounted in the same manner, adjusted, and connected with its blade assembly, as and for a like purpose, it is sufficient to identify bracket 96, pivot 97, notched bar 98 fixed to frame 1, lug 99, and link 100 by which the lever is connected with assembly 61. Each notch in one bar 94 is so related positionally with a corresponding notch of bar 98, that the two trimming blade assemblies cooperate to trim a chip to a predetermined transverse dimension or width. Thus, for example, a setting of lever 90 in a certain notch in bar 94, and of lever 95 in the corresponding notch of bar 98, will result in trimming of a chip to, say, a width of 12 inches.

A guide rod not shown, may have one end fixed to the V-shaped mount 63. The rod will be generally straight and extend rearwardly and horizontally, about in a vertical plane coinciding with the edge of the shingle to be trimmed. Thus this rod will terminate somewhere near and outside of pulley 45. This rod, while not essential, is very useful in aiding the operator to locate to a degree of precision, the line along which the chip will be severed by

blades

64, 67, and enables him to judge if the chip is of sufficient size to provide a shingle of the width for which the blade assembly is set. That is, it enables him to judge if any particular chip has one or more contractions or indentations in its edge which requires a setting of the blades for a lesser width. A like guide rod, not shown, may be similarly attached at one end to the V-mount of assembly 61, and extend rearwardly therefrom to enable the operator to estimate accurately the line of severance of the chip which these blades will effect. By such gage rods a skilled operator is able to trim each chip to the maximum standard or commercial width, so that all chips may be trimmed with a minimum waste of slate.

The operation will be generally clear from the foregoing description and is briefly resumed as follows, it being understood that one great advantage of our invention is its versatility in use, and that there are, therefore, a number of different ways in which it may be usefully employed.

The operator adjusts levers and for the desired transverse dimension of the chip to be trimmed. With motor 17 in operation and driving all conveyor belts at synchronous linear speed, he places a chip with one edge in contact with ledge 10a of slide 10 and translates the slide and chip as a unit until the leading edge of the chip is picked up by and between the upper and lower belts as they approach one another for the horizontal run. The slide is then retracted for the next chip while the chip just fed continues in translation between the contiguous horizontal runs, and is eventually passed between the right and left pairs of trimming blades.

As previously noted, the lower blades of each pair act as a rotating abutment or backing blade, and firmly support the chip at the portions thereof being instantaneously severed or trimmed. The upper blade forces downwardly the portions of the chip instantaneously contacted thereby and severs it, in cooperation with the lower blade, along a line which is parallel with the direction of travel of the chip. The line or edge of trim is clean and, as is desired, is substantially identical in appearance with that of a hand-trimmed chip.

Chips are fed in sequence and as each emerges from between the belts at the delivery end of the machine, it is picked up for transport to a machine, not shown, for drilling nail holes and subsequent packaging for sale.

Because of the facts that the horizontal contiguous runs of the conveyor belts are yieldingly urged together, they adjust automatically to any variations in thickness of the chips while maintaining, however, essentially constant the forces with which they grip the chip. At the same time, the blade pairs such as 64 and 67, being movable vertically as a unit, about the axis of shaft 62, automatically follow any slight vertical movements of the chip and thus maintain essentially constant, the forces which they exert upon the chip in effecting severance or trimming thereof. Since the axes of the two blades,

line

64 and 67, are in fixedly spaced relation, the result is a continuous clean trim along lines parallel with the direction of travel of the horizontal contiguous passes of the belts.

While we have disclosed the form of the invention presently preferred by us, numerous additions, alterations, substitutions of equivalents, changes in size, shape and relations of the parts, will readily occur to those skilled in the art, after a study of the foregoing disclosure. Hence the disclosure should be taken in an illustrative rather than a limiting sense. For example, it is known that slate chips have a grain or ribbon" and that they are customarily trimmed so that thegrain extends parallel with the longitudinal dimension of the shingle. Trimming of the chip is thus effected more facilely along the side edges of the completed shingle.

Thus it is contemplated that two machines essentially alike in structure and mode of operation may be used in a production line procedure. The first machine may have parts of relatively lighter construction, and will be used for trimming the chip parallel with the grain thereof, that is, for trimming the side edges of the shingle. This machine may have two pairs of trimming blades as in the machine disclosed, but one pair of its blades may be fixed, that is, not adjustable in the direction of shaft 62. The other pair of blades may be adjustable in the same manner and for the same purpose as are

blades

64, 67, FIG. 2. The parts of this first machine may be lighter in construction than the corresponding parts of the second machine. Its frame may be made of lighter stock and its

springs

36 and 56 may be of lower strength, etc.

The second machine while like the first one in construction and mode of operation, will trim the chip to form the end edges of the shingle. Since this machine trims across the grain,'its parts are heavier than those of the first one. For example, its frame is of heavier stock, its belts are wider and stronger, and its springs like 36 and 56 are heavier and more powerful. Its trimming blades are also of heavier stock.

The two machines may be used in production line arrangement. As each chip emerges from the first machine, with side edges trimmed, it is passed to the second one wherein the ends of the chip are trimmed. In this way the invention enables a material reduction in cost of shingles per unit area of completed product, not only in savings in time and labor, but also in the reduction to a minimum of breakage of chips.

Therefore, all variations, modifications, alterations, and substitutions of equivalents within the scope of the subjoined claims, are reserved.

Having fully disclosed the invention, what we claim and desire to secure by Letters Patent is:

1. In a machine for trimming slate chips to selected size, a frame, conveyor means mounted in said frame operable to grip and translate a chip in a fixed path lying in a first plane generally coincident with the plane of the chip, first and second circular trimming blades, a unitary element journaling said blades for rotation about a respective one of first and second fixedly related, spaced, parallel axes, and means mounting said element in said frame for pivoting about a third axis parallel with and offset from said first and second axes and with said first and second axes on respectively opposite sides of and parallel to said first plane, normal to said path, said blades being relatively slightly offset in the direction of their axes, and having peripheral portions slightly overlapping in said first plane.

2. The machine of claim 1, said element being adjustable along said third axis, and adjusting means manually operable to move and releasably fix said element in adjusted position along said third axis, with respect to said frame.

3. The machine of claim 1, said blades having sharpened beveled edges, and positioned with the planes of their sharpened edges contiguous.

4. The machine of claim 1, said conveyor means comprising upper and lower belts, guide means journaled in said frame and engaging and guiding said belts in parallel superposed contacting runs in said first plane, yielding means urging each of said runs toward the other into contact, third and fourth circular trimming blades, a second element journaling said third and fourth blades for rotation at the other side of said contacting runs of the belts, about a respective one of third and fourth fixedly related spaced parallel axes, means mounting said second element in said frame with said third and fourth axes on respectively opposite sides of and parallel to said first plane, normal to said path, said third and fourth blades being relatively slightly offset in the direction of their axes, and having peripheral portions slightly overlapping, said overlapping portions lying essentially in said first plane, said means mounting said elements comprising a single shaft fixed in said frame parallel with the axes of said blades and slightly offset from said first plane, each said element being pivotally and slidably mounted on said shaft.

5. The machine of claim 4, and first and second spring-operated means each connected with a respective one of said elements and adjustable to yieldingly urge the overlapping portions of the respective pairs of blades into said first plane.

6. The method of trimming a slate chip to size, comprising, effecting relative translation of the chip along a fixed path in its plane, with respect to, and between first and second circular trimming blades, respectively rotatable about first and second parallel fixedly related axes parallel with and on respectively opposite sides of said plane, normal to said path, the blades being slightly offset in the direction of their axes, and in slightly overlapping relation, and moving the blades as a unit in a direction normal to said plane, while maintaining fixed the direction and relation of said axes, to compensate for movements of the chip in a direction normal to said plane.

7. The machine of claim 1, said means mounting said element including means connected with said element and yieldingly urging the same to position the overlapping portions of said blades into said first plane.

8. The machine of claim 1, and means connected between said element and a fixed part of the frame, for balancing the otherwise unbalanced mass of said element and blades about said third axis.