US2968832A - Continuous mill - Google Patents

Description

Jan. 24, 1961 Filed June 5, 1958 A. HALE ETAL CONTINUOUS MILL 9 Sheets-Sheet 1 ANDREW HALE, BOYD A. Mc CLELLAN 8| ROBERT L. GU ENJHEIM ATTORNEYS A; HALE ETAL CONTINUOUS MILL Jan. 24, 1961 9 Sheets-Sheet 2 Filed June 5, 1958 V INVENTORS ANDREW HALE BOYD A. McCLELLAN a ROBERT .eu GENHEIM BY 860,, 7 m

ATTORNEYS A. HALE ErAL CONTINUOUS MILL Jan. 24, 1961 9 Sheets-Sheet 3 Filed June 5, 1958 lil I/ 5 Jan. 24, 1961 A. HALE ETAL 2,968,832

CONTINUOUS MILL Filed June 5, 1958 9 Sheets-Sheet 4 FIG. 4

INVENTORS ANDREW HALE,

BOYD A.McCLELLAN 8 ROBERT L. GUGGENHEIM ATTORNEYS A. HALE ETAL CONTINUOUS MILL Jan. 24, 1961 9 Sheets-Sheet 5 Filed June 5, 1958 Jan. 24, 1961 A. HALE ETAL 2,968,832

CONTINUOUS MILL Filed June 5, 1958 9 Sheets-Sheet 6 94 INVENTORS ANDREW HALE, BOYD A. Mc CLELLAN Bu ROBERT L. GUGGENHEIM ATTORNEYS A. HALE EI'AL CONTINUOUS MILL Jan. 24, 1961 9 Sheets-Sheet 8 Filed June 5, 1958 lll5 b m EN E mLA N A R HHfl 0 WLG WW IECU YA m M Q im? D uo YB Z 00 BRY. B

Jan. 24, 1961 A. HALE ETAL 2,968,832

connuuous MILL l 56 5 INVENTORS I65 I67 ANDREW HALE,

gaT vea ass evM l55a. ROB H FIG. I?

ATTORNEYS United States Patent "ice CONTINUOUS MILL Andrew Hale, Akron, Boyd A. McClellan, Mogadore, and Robert L. Guggenheim, Cuyahoga Falls, Ohio,

. assignors, by mesne assignments, to Blaw-Knox Company, Pittsburgh, Pa., a corporation of Delaware Filed June 5, 1958, Ser. No. 740,047

8 Claims. (Cl. 182) The present invention relates to apparatus for milling plastic or rubber stock and is in the nature of an improvement upon apparatus shown in the Hale and Kullgren Patent No. 2,663,901, issued December 29, 1953. v

The mill of the aforesaid patent was designed primarily for the continuous milling of rubber, although the basic principles of the machine and the mechanism shown therein were adaptable for the milling of synthetic materials having plastic properties similar or analogous to the properties of natural or synthetic rubbers.

In the case of certain synthetic resins such as polyethylenes, polystyrenes, polyvinyls and others, the stock is frequently produced in granular, flake or pellet-like form which requires a milling operation to dissipate water from the stock as Well as to plasticize and blend the stock for further use. In addition, the pellet or granular form of the stock is not suitable for certain further operations and the stock should be converted into sheet form or at least into a matted condition for further handling.

It has been found that a mill embodying the principles of the aforesaid Hale and Kullgren patent is admirably suited to this type of work, but it is desirable to improve the mechanism in certain of its features in order to meet certain special requirements for the work referred to above and to improve the ease of operation and maintenance and the productive capacity of the mill.

The mill shown herein has certain features of improvement over the mill of the prior patent, as will be pointed out. The mill shown and described herein is intended to run at high speed and to process large quantities of the synthetic materials economically and efiiciently.

It is also a purpose of the invention to improve upon the construction and design of the deflector blades and other elements which come in contact with the mill rolls so that they will be better adapted for high speed operations at high temperatures and will not abrade the rolls.

. The mill employs a series of deflector blade assemblies carried above the mill rolls in a manner permitting use of a varied number of deflector blades adjusted to desired angular settings. The deflector blades cut the stock while being milled into successive strips which are turned or rolled to form convolute rolls of stock. The stock is thus repeatedly subdivided and as it advances along the work roll it is thoroughly worked and treated by repeated passages through the bite of the mill rolls. The stock will'have the desired consistency when delivered at the end or ends of thework roll, where a final strip of the milled stock is cut oft" and removed from the work roll by suitable conveying equipment.

It is also a purpose of the invention to improve upon the design of the feeding mechanism for charging raw pellets or flakes of stock into the mill.

In the drawings, the mill is shown as a double-acting mill in that the raw plastic stock is fed to the center of thezrolls and passes to both ends of the work roll by the succession of vanes or deflector blades which cut the sheet as it forms on the work roll into strips, which are Patented Jan. 24, 1961 turned or deflected so they are successively directed into a rolling bank of stock at the roll bite and progressively advanced toward the take-off points while receiving a multiplicity of workings en route. The principles of this invention may also be applied to a single acting mill, in which the raw material is fed into the mill rolls at one end and advanced across the entire face of the rolls to the discharge point at the far ends of the rolls, or to a vertical mill or to a three-way mill. 1

It will also be understood that the present machine is adaptable for use in the continuous milling of rubber, natural or synthetic, as well as the so-called synthetic plastic materials.

.In the drawings, in which the continuous mill is shown in its best known andpreferred form:

Fig. -1 is a front elevation of the mill; the details of the drive mechanism and the means for supplying and regulating the temperature regulating fluid (usually heated water) are not shown as these are within the knowledge of those skilled in the art,

Fig. 2 is a plan view,

Fig. 3 is a vertical sectional view through the roll housiugs, taken substantially on line 33 of Fig. 2,

Fig. 4 is a vertical sectional view through a centra point on the rolls'where the feed hopper is located, taken substantially on line 4-4 of Fig. 2,

Fig. 5 is a side view showing the hoisting mechanism for the feed hopper and deflector blade carriage, taken substantially on line 55 of Fig. 1,

Fig. 6 is a section on the line 6-6 of Fig. 5,

Fig. 7 is a section on the line 7--7 of Fig. 5,

Fig. 8 is a section on the line 8-8 of Fig. 5,

Fig. 9 is a section on the line 9-9 of 'Fig. 5,

Fig. 10 is a side view of the feed hopper, taken substantially on line 1010 of Fig. 2,

Fig. 11 is a plan view of the feed hopper, taken substantially on line 1111 of Fig. 10,

Fig. 12 is a front view of the feed hopper, taken substantially on line 12-12 of Fig. 10,

Fig. 13 is a section through the feed hopper on the line 1313 of Fig. 10,

Fig. 14 is a side elevation of a typical deflector blade assembly taken substantially on line 14-14 of Fig. 2

Fig. 15 is a side elevation of the blade assembly at the end of the rolls, taken substantially on line 15--15 of Fig. 2,

Fig. 16 is a section showing a detail :at the lower tip of the end plate on line 16-16 of Fig. 15,

Fig. 17 is a top view of this portion of the end plate on line 1717 of Fig. 15,

Fig. 18 is a side view showing a form of cut-01f blade to sever a strip of stock for removal from the mill work roll.

The mill construction A horizontal two-roll mill embodying the invention is indicated at 20. The feed roll is the front smaller diameter roll 21. The work roll is the rear larger diameter roll 22. The rolls rotate toward each other in the direction of the arrows placed upon them in several of the views and are adjustable toward and from each other to vary the width of the bite 23 which is created at the point where the rolls are closest together. The rolls are preferably chrome-plated for working on plastics and are hollow or cored for the passage of temperature reg ulating fluid therethrough. In the milling of-certain types of plastics, for which this press is especially designed, the work roll normally travels at a higher surface speed than the feed roll. A typical surface speed of the work roll is about feet per minute. For milling plastic stocks of certain types, roll temperatures as high as 350 to 375 F. may be obtained. The feed roll is preferably aeeaaas made with a slight chamfer so that it is a few thousandths of an inch thicker at the center line of the roll which assists in the progressive movement of the stock toward the ends of the work roll.

best shown in Fig. 3, the roll ends 21' and 22' .are .journaled in bearing blocks 24 and 25. The blocks 25 are horizontally adjustable along a slide '26 in an end housing 27. The two end housings 27 each have a roll adjusting screw 28. Between the two bearing blocks on each .side of the mill is a heavy cushion spring assembly 29. The screw .28 is threaded in a bearing sleeve 28:: which is rotatable in the housing so that by turning the screw 28 by the lever 28b and .rotating the :sleeve 28a, amicrometer adjustment of the spacing between the rolls may be obtained. The inner end of each screw 28 is connected to a clevis 28c through which is passed ashear pin 28d, the endsof which are located in lugs .28e on the bearing block 24. These shear pins will prevent injury :to the rolls in case a foreign substance enters the bite of the rolls.

The end housings 27 are carried on a bed plate 30 .adapted for attachment as by bolts 31 to a foundation. The two rolls are driven (see Fig. 2) in a manner common to mills of this type by a motor driven pinion shaft '32 and suitable gears 33 carried on the roll ends21' and 22, those at the left of Fig. 2 being omitted.

Apron and feed -r0,ll scraper The mill 20 also includes an apron or casement assembly, indicated generally at 35, located between the end housings 27 on aplate 36 across the members of the bed plate 30. As best shown in Fig. 4, the endless belt 37 of rubber or other suitable material is supported by a series of rollers carried by a structural frame. The lower rollers 38 and 39 are journaled in a horizontal vrectangular member 40. vAn intermediate roller 41 is journaled at "the upper end' of a vertical rectangular member 42. The drive roller 43 is journaled at the upper end of a short rectangular member 44 directed inwardly to a point slightly above the periphery of roll 22. The structural frame composed of members 40, 42 and 44 is preferably covered With a sheet metal guard 45.

' The roller 43 is driven by a shaft 46 (see Fig. 2) and sprocket drive 47 from a suitable power take-off on the maindrivepinion 32. The roller 43 drives the belt 37 at a lineal speed which is preferably equal to the peripheral speed of the work roll 22.

' The apron or belt 37 is located at the region where the fresh stock .is fed to the rolls and its, purpose is to hold the unmilled stock during its first pass or passes, especially when charged in pelletized form as described in detail below, against the medial portion of roll 22. It

prevents the pellets from dropping off the work roll until they have sheeted or matted sufficiently to cling to the work roll.

It is desirable that the assembly 35 be easily removed for maintenance purposes such as cleaning or when its presence is not necessary. In order that the assembly 35; be replaced easily, the lower structural member 40 is provided with wheels 47 at each. corner thereof. The wheels 47 run on parallel track members 48 atop the plate 36. When the wheels 47 engage tracks 48, the member 40 is aligned by corner dowels 49 (.seeFig. 1) and; locked in position by a bolt 50 threaded through a stud plate 51 attached tothe plate 36.

The mill 20 also preferably includes a .scraperblade 53 extendingacross the front face of feed roll21. As best shown in Fig. 4, the blade 53 is carried by a swinging frame 54 pivoting on a shaft 55 journaled in hub blocks .56-attached to both end housings27; The blade-53 is mpvedtoward and from thesurface ofroll 21 to remove fragments of stock adhering theretobyna pair. .of-pneumaticcylinders, 58mounted on the end housings :and connested; to frame 5.4.:by a linkage. 59. The. blade53 is preferably made from a block of nylon or similar synthetic material which is also used for the deflector blades as will be described more indetail in the description of said blades.

Feed hopper and deflector blade carriage The mill 20 also includes a feed hopper and deflector blade carriage, indicated generally at 60, which may be raised above the rolls 21 and 22 for repair or replacement of the blades, for adjusting the blades, for obtaining access to the rolls, or for other purposes. Extending across the top of each end'housing 27 is a heavy reinforced cap member 62. Each cap member is attached by bolts 63 to an end housing.

As best shown in Figs. 2 and 3, on the upper front surface of each cap member 62 is a bearing block 64. Extending between the cap members 62 and journaled in the blocks 64 is a carriage shaft 65 having extensions 65 projecting at either end beyond the cap members. The shaft 65 provides a bearing surface and pivot point for a pair of carriage blocks 66 and side members 67 extending rearwardly therefrom. At the rear of the mill above roll 22, the side members 67 are cross-connected by a hollow shaft 68 received in bosses 69 on the ends of the side members. Above roll 21, the side members 67 are cross-connected by a hollow shaft 70 received in bosses 71 on the side members. The shafts 68 and 70 support the deflector blades as will be described.

The shafts 68 and 70 have extensions 68' and 70', respectively, projecting at either end beyond the carriage side members 67. Fitted on the rear shaft extensions 68' are annular guide collars 72 each having specially contoured peripheral surfaces 73 (see Fig. 9) adapted to be received in a cooperating slotted guide bracket 74 on a cap member 62. Each bracket 74 has a pair of clamps 75 pivoted to the bracket and held down by bolts 76 so as to lock the carriage 60 in its lowered position. The front shaft extensions 78' carry similar guide collars 77 adapted to engage guide brackets 78 on the cap members 62. When the frame 60 is lowered, the guide collars 72 and 77 will engage guide brackets 74 and 78 and align the frame in relation to the end housings 27 and the mill rolls.

Carriage hoist,

The carriage 60 is raised pivoting on shaft 65, by a mechanism details of which are shown in Figs. 5-9. Outwardly of a bearing block 64, each shaft extension 65 has keyed thereon a large diameter drum 80 having a preferably multi-wind grooved face. The right-hand shaft extension 65 (as viewed in Fig. 1) has a further extension 81 carrying a coupling 82 engaging the output shaft 83 of a gear reduction unit 84 operated by a handle 85, or motor driven if desired. The gear reduction unit may be mounted on a bracket 86 secured to the outer surface of the right hand cap member 62. The gear reduction unit is a self-locking type of drive which insures that the carriage is held in raised position and can not be lowered except through the operation of the unit.

A hoist cable 88 is secured at one end to each drum,

80, wrapped therearound several times and led out so as to pass under an idler pulley 89. Each pulley 89 is rotatably mounted on a stub shaft 89a held by flange 89b in a socket in a bearing block 89c (see Fig. 7) near the bottom of an upwardly extending bracket 50 secured to a cap member 62 between the aligning brackets 74 and 78. A stub shaft 91a is held by a fiange 91b in a socket in a bearing block 910 at the upper end of each bracket 90. Two coaxial pulleys 91 and 92 are rotatably mount-- ed on each stub shaft. The strand of cable 88 from the low pulley '89 passes up to and over the inside pulley'9i From the inside upper pulley'91, the strand of'cabl'e 88 then passes down to and around the inner of 'two' co axial pulleys' 93 and 94. As best shown in Fig. 9," fitted in each open end of shaft 68 is a plug 95 to which is attached as by bolts 96 a downwardly directed arm 97. Rotatably mounted on the low end of arm 97 are the inside smaller diameter pulley 93 and the outside larger diameter pulley 94.

From the inside rear pulley 93, the strand of cable 88 then passes up to and around the outside upper pulley 92 then down to and around the outside rear pulley 94. From pulley 94, the cable runs back to the top of bracket 90 where the end is anchored by an adjustable rod 99a to a pin 98 on a forwardly extended lug 99 at the top of the bracket 90.

The arrangement for cable and pulleys as shown has been found to furnish a maximum torque so that the carriage 60 can be raised and lowered after releasing the clamp 75 by manual rotation of the hand wheel 85. As the large pulley 80 is rotated to wrap the cable about it, the shortening of the cable will raise the entire carriage to the position indicated in dotted lines in Fig. 5, with its attached feed hopper and deflector blades exposing the upper surfaces of the rolls 21 and 22.

Feed hopper The mill 20 also includes a feed hopper assembly, indicated generally by the numeral 100 extending rearwardly of the mill from support shaft 70 of the carriage 60. The hopper is adjustable to vary the amount of pellets or raw stock which is fed to the mill above the bite between the rolls 21 and 22. As shown in Figs. 1 and 2, the hopper assembly 100 is located on the center line of the mill. This location is used when the mill is double-acting; that is, when milled stock is being taken off at both ends of the mill. If the stock is to be fed to one end of the mill, the hopper is shifted accordingly. In such case, the chamfer on the feed roll is changed so as to advance the stock along the bite of the rolls.

The details of the feed hopper assembly 100 are shown on Figs. 13. The raw stock is delivered by suitable conveyor means (not shown) to an outwardly flared receiver 101. Below the receiver 101 is a preferably rectilinear throat defined by front and rear wall plates 102 and two side wall plates 103. The front and rear wall plates 102 extend downwardly terminating just above the mill rolls and are provided with lateral ears 104 holding tie rods 105 with stop nuts 106 threaded thereon which brace the side of the hopper and which may be loosened to permit adjustment of the side wall plate extensions. The side wall plates 103 extend downwardly only a short distance, terminating on approximately the plane of the carriage shafts 68 and 70. Attached to the lower surface of each side plate 103 is a deflector plate hinge block 107 having an inner facing horizontal slot 108 receiving the outwardly directed flange bead 109 of a swinging deflector plate 110 which constitutes an adjustable extension of the plate 103.

As best seen in Fig. 12, the deflector plates 110 swing inwardly from the maximum open position (shown in chain lines) to a minimum open position. The width of the opening between the lower ends of the deflector plates 110 (which varies for example from 6 to 9 inches) is adjusted by a double-threaded shaft 112 engaged with stud blocks 113 on the ends of shafts 114 journaled in cars 115 on the plate 110. The mid portion of bolt 112 is journaled in a pair of bearing blocks 116 on the front wall plate 102. Between blocks 116, a small sprocket 117 is keyed to the bolt 112. The sprocket 117 is rotated to adjust the deflector plates by a chain 118 running around a hub sprocket 119 journaled on the carriage shaft 65 and having'an operating wheel 120' This novel method of adjusting the discharge opening at the lower end of the feed hopper affords an easily operated means of varying the amount of stock or pellets without Interrupting the operation of te mill. The operator thus has an accurate and easy means of conrolling the amount of raw stock which is being processed in he m l 1 To prevent stock or pellets from falling to one side or the other of the zone in which they are fed, and thus to insure that they pass through the desired bite area 23 on the first pass, the lower ends of the deflector plates are provided with side boards indicated at 122. Each side board has a long depending portion 123, of nylon or other suitable wear-resistant material as described in detail below, the lower edges of which are arcuate as shown in Fig. 10 so as to extend into close proximity with the roll bite 23 and to contact the roll surfaces. Each depending portion 123 is fastened as by bolts 124 to a bracket 125 on the lower end of each plate 110. To further define the charging area, each bracket 125 also carries a pair of inwardly projecting plates 126 which just touch when the hopper is at the minimum opening position.

The feed hopper is pivotally supported between two arms 128 extending rearwardly from a heavy clamp 129 keyed on the shaft 70. Each clamp is held in position on the shaft 70 between a second clamp 130 connected thereto by a cross lug 131 and bolt 132 and an outer annular lock ring 133. The support end of each arm 128 has a cap plate 134 and a transverse bore receiving a pivot pin 135 extending from a mounting plate 136 on the side wall plates 103.

The hopper assembly 100 also includes a divider blade 138 depending over the Work roll 22 from a support extending forwardly of the mill from support shaft 68. The divider blade is generally wedge or V-shaped pointing to the rear of the mill so that the charged stock after its first pass around the work roll will be diverted and pass to either side of the hopper side boards 122. The divergent blade portions 140, of nylon or other suitable wear-resistant material are described in detail below. These blades conform to the contour of the surface of work roll 22 and are fastened as by bolts 141 to a V-shaped bracket 142. The upper surface of bracket 142 has three triangularly disposed blind bores 143 receiving the lower end of three floating shafts 144. The shafts 144 extend through vertical bosses in a Y-shaped support arm 146. The upper end of each bore plug 146 for a shaft 144 is threaded to receive a tension adjusting plug 147. The middle portion of each shaft 144 has a reduced diameter so that a compression spring 148 may be seated thereon. The spring 148 presses against plug 147 :to resiliently urge the divider blades against the surface of roll 22. To prevent the shafts 144 from dropping out of bosses 146 when the carriage assembly 60 is hoisted, a collar 149 is fitted on the upper end of each shaft 144.

The end portion 150 of the arm has a heavy clamp 151 which surrounds and is keyed to shaft 68. The clamp 151 is adjustable along shaft 68 so that the divider blade may be aligned as required with the feed hopper 100.

Deflector blade assemblies The mill 20 also provides for the use of a number of vanes or deflector blades which cut the sheet of stock as it forms on the work roll 22 in strips, which are turned or rolled to form convolute rolls of stock which are we cessively directed into a rolling bank of stock (shown in dotted lines in Fig. 3) above the roll bite 23.

As the stock is fed into the bite between the two rolls it will pass through the narrow bite between the rolls and spread out along the work roll to which it adheres. The thin sheet of stock on the work roll is repeatedly severed by the sharp edges of the blades and rolled or deflected toward the ends of the roll. As the operation continues the stock receives a plurality of workings which thoroughly mills the stock so that homogeneoussheets are delivered at the ends of the rolls. If the feed hopper is in the center of the mill two separate milling operations will be proceeding in opposite directions simultaneously and two ribbons or lengths of mill stock will be delivered. If, however, the feed hopper is at one end of the roll the stock will progress along the roll and be delivered at the other end of the mill as one ribbon.

Referring to Fig. 2, the individual deflector blade assemblies indicated generally at 153, extend between support'shafts 68 and 70 of the carriage assembly 60.

In Fig. 2, to the right of the hopper assembly 100, there are shown eleven deflector blade assemblies 153 set at selected angles and an end deflector blade assembly set transversely of the work roll 22. To the left of the hopper 100, there are shown only five angular deflector blade assemblies and the end deflector blade assembly. This particular arrangement is illustrative of the versatility of mill 20, and is intended to illustrate that the mill may be set and adjusted so that the stock in the mill may be subdivided and reworked to any extent depending upon the number of blades which are located along the work roll.

An additional advantage of a mill according to the invention is that the blade assemblies 153 are identically constructed except for a slight modification to the blade portion of an assembly 153 being used as at the end of the work roll 22. Thus, the operator can add or subtract assemblies, change their angular setting, and make other adjustments which permit versatile employment of a mill 20. In changing the angular positioning of a blade with respect to the mill roll, it will be necessary to grind the lower edge of a blade to make it fit on the roll at a different angular setting or to substitute new blades cut and ground for a specific angular setting.

A standard blade assembly is shown in Fig. 14. A blade assembly modified for use at the end of a roll is shown in Fig. 15. The manner in which the blades are setat different angles with respect to the work roll is shown in Fig. 2.

A deflector blade 155, of nylon or other suitable wear and heat resistant material described in detail below, conforming with and fitting closely to the contour of the surface of work roll 22, is attached as by bolts 156 to a bracket 157. The leading edge of each blade is sharpened as shown at 1551) to sever the sheet of stock. The upper edge of bracket 157 has a pair of bores 158 receiving the lower end of a pair of floating shafts 159. The shafts 159 extend through vertical bosses in a link arm 160. The upper end of each boss 161 is threaded to receive a tension adjusting plug 162. The middle portion of each shaft 159 has a reduced diameter so that a compression spring 163 may be seated thereon. The spring 163 presses against plug 162 to resiliently urge the deflector blade with yielding pressure against the surface of roll 22. To prevent the shafts 159 from dropping out of bosses 161 when the carriage assembly 60 is hoisted, a collar 164 is fitted on the upper end of each shaft 159.

Referring to Figs. 15, 16 and 17, the blade assembly modified for use at the end of a roll 22 has a link 165 depending from the lower end of bracket 157. It will be noted that the end blades are normaly set at right angles to the axis of the work roll and their purpose is to prevent the stock from passing off the ends of the roll. The blade at the end of the roll is designated as 155a. .A tip blade portion 166 conforming with the contour of the surface of rolls 21 and 22 and extending into close proximity with the roll bite 23, of the same material as blade portion 15 a, is attached as by bolt 167 to the lower end of link 165. The reason for this modification is that, due to the fact that the end of the blade fits into the bite between the rolls, the swinging movement of the frame when it is being elevated requires that the end of the blade be pivoted soas to move in and'out of its position in the bite.

One end of each link arm 160 is provided with an elongated. clevis portion 170 receiving a lower clamp member 171; The clevis held end of member 1'71 has a longitudinal slot 172 through which a clevis pin. 173 is inserted. The'other end of member 171 is adapted to partially surround the shaft 70; is keyed thereto, and is &

secured thereon by an upper clamp member 174 and bolts 175. The other end of each link arm is provided with a somewhat shorter clevis portion 176 receiving a lower clamp member 177 having a bore 178- through which a clevis pin 179 is inserted. The other end of member 177 is also adapted to engage shaft 68 and is secured thereon by a similar upper clamp member 180 and bolts 181.

The clamp members 171 and 174, and 177 and 180, are adjustable along their respective support shafts (68 or 70) with the slots 172 permitting any desired angular setting of the blade within the limits provided by the slots. As noted above the differences in curvature of the lower edges of the deflector blades so that they will fit the roll 22 is done by grinding the blade so as to get an exact fit between each blade and the surface of the roll 22. It will be noted that when there are a large number of deflector blades in use, the blade holding link arms 160 may be reversed as shown in Fig. 2 to avoid interference between the bosses 1-61 for the spring pressed plugs 162.

In the case of each element which bears against the rolls, whether the subdividing and deflecting blades or the blades at the ends of the rolls or the large scraper blade for the feed roll or the blade which removes the ribbon of stock and the lower edges of the hopper, that portion of the element which bears against its roll is a solid block of a synthetic resin which is of a composition which will withstand the heat of the rolls, and which will not mar or abrade the surface of the roll which for milling plastics should preferably be chrome plated. For the purpose we have found that a nylon molding compound, which is manufactured by Polypenco Inc., Reading, Pennsylvania, and known as Polypenco #101, is admirably suited for the purpose.

A polytetrafiuorethylene molding compound known by the trade name Teflon may also be used. It is possible in the advance of the plastic arts that other resins may be developed which will have like properties and it is not intended to restrict the claims directed to this feature to the above named materials. What is required is a synthetic resin molding compound which will have a sufliciently high melting point to withstand the high temperature, can be formed and ground to fit the roll and will not abrade the rolls or mar the high polished surface.

Conclusion and summary As described above, a mill 20 according to the invention is charged with raw unmilled stock through the feed hopper assembly. The material can be subdivided, worked and turned or rolled any desired number of times by the deflector blade assemblies as it passes from the feed area toward the ends of the work roll. The stock reaches the work roll ends in sheet form and is cut off and a strip continuously fed to suitable conveying equipment (not shown) to be removed from the mill as a continuous strip or strips.

Referring specifically to Fig. 18, one form of cut-off knife which may be used on a mill 20 is shown. An adjustable blade of desired width extends parallel to the work roll 22. The blade 185 is of the same material as the deflector blades and is carried by a back-up fram 186 pivoting on a shaft 187 extending from a bracket 188 attached to an end housing 27. The blade 185 is kept against the surface of roll 22 to sever the milled stock for removal by a pneumatic cylinder 189 also mounted on an end housing and connected to the frame by linkage 190. The knife will remove a continuous strip.

While a mill 2% embodying preferred forms of the invention has been shown and described, it Will be apparent that changes or modifications could be made therein which would lie within the scope of the invention.

What is claimed is:

1. Apparatus for milling plastic stock comprising, a base having end housings, mill rolls side-by-side between said end housings, a carriage between said end housings above said rolls, means pivotally mounting said carriage on said end housings laterally of the bite between said rolls, a hopper pivoted on said carriage for discharging raw stock between said rolls, a series of deflector blades on said carriage and normally bearing against one of said rolls to cut and turn strips of stock for repeated passage between the rolls, and means to raise the carriage to lift the blades and hopper from the rolls.

2. Apparatus for milling plastic stock comprising, a base having end housings, mill rolls side-by-side between said end housings, a carriage between said end housings above said rolls, means pivotally mounting said carriage on said end housings laterally of the bite between said rolls, a hopper pivoted on said carriage for discharging raw stock between said rolls, a series of deflector blades on said carriage and normally bearing against one of said rolls to cut and turn strips of stock for repeated passage between the rolls, and means to raise the carriage to lift the blades and hopper from the rolls, said hopper having walls fitting into the bite of the rolls in the lowered position of said carriage.

3. Apparatus for milling plastic stock comprising, a base having end housings, mill rolls side-by-side between said end housings, a carriage between said end housings above said rolls, means pivotally mounting said carriage on said end housings laterally of the bite between said rolls, a hopper pivoted on said carriage for discharging raw stock between said rolls, a series of deflector blades on said carriage, means resiliently mounting said deflector blades on said carriage normally to bear against one of said rolls to cut and turn strips of stock for repeated passage between the rolls, and means to raise the carriage to lift the blades and the hopper from the rolls.

4. Apparatus for milling plastic stock comprising, a base having end housings, mill rolls side-by-side between said end housings, a carriage between said end housings above said rolls, means pivotally mounting said carriage on said end housings laterally of the bite between said rolls, a hopper pivoted on said carriage for discharging raw stock between said rolls, a series of deflector blades on said carriage, means resiliently mounting said deflector blades on said carriage normally to bear against one of said rolls to cut and turn strips of stock for repeated passage between the rolls, and means to raise the carriage to lift the blades and the hopper from the rolls, said hopper having walls fitting into the bite of the rolls in the lowered position of said carriage.

5. Apparatus for milling stock comprising, a base having end housings, mill rolls mounted between said end housings, a carriage shaft extending between said end housings above one of said rolls, a carriage pivotally mounted on said carriage shaft and supported from said end housings above said rolls, means to raise and lower said carriage, and a hopper pivoted on said carriage discharging pellets of stock between said rollers, said hopper including a throat defined by front, rear and side wall plates, said front and rear wall plates extending downwardly into close proximity with said rolls in the lowered position of said carriage, said side wall plates terminating substantially above said rolls, swinging plates connected to said side wall plates, means coupling said swinging plates, and actuating means extending between said coupling means and said carriage shaft for moving the lower ends of said swinging plates toward and from each other between said front and rear wall plates.

6. Apparatus for milling plastic stock comprising, a pair of end housings, a feed roll and a work roll mounted between said end housings rotating toward each other, a cap member extending across the top of each end housing, a carriage shaft extending between said cap members above said feed roll, side members carried on said carriage shaft extending transversely of said rolls, a first cross shaft connecting said side members above said feed roll, a second cross shaft connecting said side members above said work roll, means to rotate said carriage shaft to raise said side members and cross shafts, a series of linked assemblies extending between said first and second cross shafts and adjustable longitudinally thereon, and deflector blades resiliently carried by each of said assemblies, the leading edges of the blades being sharpened and the lower edges thereof contacting the surface of said work roll to cut and turn strips of stock for passage between said rolls, said assemblies being adjustable differentially on said first and second cross shafts to vary the angularity of said blades.

7. Apparatus for milling plastic stock comprising, a pair of end housings, a feed roll and a work roll mounted between said end housings, a cap member extending across the top of each end housing, a carriage shaft extending between said cap members above said feed roll, side members carried on said carriage shaft extending transversely of said rolls, a first cross shaft connecting said side members above said feed roll, a second cross shaft connecting said side members above said work roll, means to rotate said carriage shaft to raise said side members and cross shafts, feed means plvotally carried by said first cross shaft for charging raw stock between said rolls, a series of linked assemblies on either side of said feed means extending between said first and second cross shafts and individually adjustable longitudinally thereon, and deflector blades resiliently carried by each of said assemblies contacting the surface of said work roll to cut and turn strips of stock for passage between said rolls, said assemblies being adjustable differentially on said first and second cross shafts to vary the angularity of said blades.

8. Apparatus for milling a plastic stock comprising a pair of rotating mill rolls about one of which the stock is formed as a sheet, a carriage pivoted above the rolls for swinging to and from the rolls, a pair of parallel cross shafts mounted on the carriage above the rolls, a series of linked assemblies extending between said cross shafts, deflector blades resiliently carried by said assemblies normally in contact with the stock-carrying roll, and the ends of said assemblies being independently adjustable on said cross shafts to vary the angularity of said deflector blades, the leading edges of the blades being sharpened and the lower edges thereof normally contacting the surface of the stock-carrying roll to cut and turn strips of stock for passage between said rolls, the lower edges of said blades being composed of a synthetic resin having a melting point to withstand temperatures of 350 F. and above.

References Cited in the file of this patent UNITED STATES PATENTS 1,418,642 Gerard June 6, 1922 1,736,582 Davidson Nov. 19, 1929 1,930,736 Burrell Oct. 17, 1933 2,625,709 Schairer Jan. 20, 1953 2,652,590 Sullivan et al. Sept. 22, 1953 2,663,901 Hale et al. Dec. 29, 1953 2,713,698 Danby et al. July 26, 1955 2,730,755 Hale et al. Jan. 17, 1956

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