US3482833A

US3482833A - Sheet feeder assembly

Info

Publication number: US3482833A
Application number: US670261A
Authority: US
Inventors: Albert Lester Schleiden
Original assignee: MILLER PRINTING MACHINERY Co
Current assignee: MILLER PRINTING EQUIPMENT Corp A CORP OF DE
Priority date: 1967-09-25
Filing date: 1967-09-25
Publication date: 1969-12-09
Anticipated expiration: 1986-12-09
Also published as: GB1240164A; FR1579392A; CH479474A; DE1786232A1

Description

Dec. 9, 1969 A. L SCHLEIDE N SHEET FEEDER ASSEMBLY 2 Sheets-Sheet 1 Filed Sept. 25, 1967 3 mw R wlil. up.

INVENTOR.

ALBERT SCHLEIDEN H/S ATTORNE Y5 Dec. 9, 1969 A. SCHLEIDEN 3,482,833

SHEET FEEDER ASSEMBLY Filed Sept. 25, 67 2 Sheets-Sheet 2 INVENTOR.

ALBERT L. SCHLEIDEN E3 MW,

H/S ATTORNEYS United States Patent 3,482,833 SHEET FEEDER ASSEMBLY Albert Lester Schleiden, Pittsburgh, Pa., assignor to Miller Printing Machinery (10., Pittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 25, 1967, Ser. No. 670,261 Int. Cl. B65h 3/08, 5/10 US. Cl. 271-26 7 Claims ABSTRACT OF THE DISCLOSURE A sheet feeder assembly having a suction means for picking up the top sheet from a pile of sheets and transporting it in a horizontal path. Blowing nozzles are provided for maintaining the top sheet separated from the pile of sheets by blowing air under the top sheet. The blowing nozzles move horizontally at the same rate and in the same direction as the horizontally moving suction means. Horizontally disposed adjustable guides, supported at both ends, overlying the pile to control the upward movement of the sheet.

FIELD OF THE INVENTION This invention relates to a sheet feeder assembly for printing presses, as well as cutting and creasing presses and the like, which provides more effective distribution of air under the sheet being raised. More specifically this invention relates to such an assembly having a blower move along with the sheet as the sheet passes through the feeder.

DESCRIPTION OF THE PRIOR ART It has been known in printing presses and similar equipment requiring the handling of individual sheets of material, to provide a :pile of sheets and remove one at a time for transporting to the appropriate portion of the equipment.

In such systems it is customary to lift the top sheet of the pile by means of a suction tube which terminates in a suction foot contacting the top sheet adjacent one end thereof. As the suction foot is raised, the secured end of the sheet is raised. To further separation of the remainder of the sheet, air is blown under the sheet through an adjacent blower nozzle. The sheet thus separated is then generally transported horizontally by means of other suction tubes and delivered to a sheet receiver, such as a pair of pinch rolls. Generally, the blower nozzle begins to provide air as the top sheet is lifted and continues to provide air until the sheet has been horizontally transported and released. Such a system is disclosed in United States Patent 3,006,638.

In the conventional system, the air supply nozzle is stationary and therefore as the sheet is moved away from the nozzle, the integrity of the air cushion is substantially impaired. The path of air flow from the nozzle may generally be considered to be of conical shape. As a result, as the sheet moves away from the air nozzle, the air is not always provided under the sheet, as is desired, and a substantial portion of the air flows on top of the sheet. This air fiow on top of the sheet tends to induce fluttering and loss of control to the sheet which interfered with the efficiency of the sheet feeder in feeding the sheets in timed relation into the sheet receiver. It is conventional to provide a series of overlying bars which limit the extent of vertical movement of the sheet and thereby help control the sheet. As these overlying bars are conventionally supported at only one end and are of fixed dimension, the support is not rigid and is frequently not of adequate length for the particular size of sheet. The lack of uniform air supply under the sheet 3,482,833 Patented Dec. 9, 1969 ice and a lack of suitable overlying support therefore, remain a problem in sheet feeders.

It is an object of this invention to provide a sheet feeder assembly adapted to supply a uniform air stream support for a separated sheet during the entire period it is retained and transported by the suction tubes.

It is another object of this invention to provide a sheet feeder assembly having air supply means which will facilitate retaining the sheet in substantially flat position throughout its passage through the feeder.

It is another object of this invention to provide a sheet feeder assembly adapted to provide effective delivery of individual sheets which assembly may be readily adjusted for use with various sheet sizes.

Other objects and advantages of this invention will be understood from the following description of the invention on reference to the illustrations appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIGURE 1 is a fragmentary view in side elevation partially schematic, illustrating the improved sheet feeder assembly.

FIGURE 2 is a fragmentary view in elevation and partially schematic, illustrating a pile hold down device adapted for use with the sheet feeder illustrated in FIG- URE 1.

FIGURE 3 is a top plan view, partially in section, taken along the line 3- 3 of FIGURE 1 and illustrating schematically the forward or advanced position of the suction member and the blower nozzle.

FIGURE 4 is a fragmentary view in end elevation taken along the line 44 of FIGURE 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS General description Referring to the drawings, the feeder assembly has a sheet pile 1 with a top sheet 2 indicated in dotted lines in FIGURE 1, being raised therefrom. For convenience of discussion it will be assumed that the top sheet 2 shown in FIGURE 1 will be moved through the feeder from the right toward the left. The left side of the sheet will be referred to as the front or leading edge portion 8 and the right side will be referred to as the rear edge portion 9. Positioned adjacent the rear edge portion 9 of the top sheet 2 are a plurality of suction lifting members 3 which are adapted to raise the rear edge portion 9 of the top sheet 2 from the pile 1. Restraining the rear edge portion 9 of the top sheet 2 are a plurality of sheet hold down devices generally designated by the numeral 4.

A plurality of suction forwarding members 5 are adapted to receive the top sheet 2 adjacent its rear edge portion 9 after the rear edge portion has been raised by suction lifting members 3. The suction forwarding members 5 are arranged to move the top sheet 2 forwardly. The top sheet 2 engaged by suction forwarding members 5 is illustrated in FIGURE 1. Blowing nozzles 6 supply an air stream to the underside of the rear edge portion 9 of the top sheet 2 as it is raised from the pile 1 and continues to do so as the sheet 2 is moved forwardly by the suction forwarding members 5. Sheet guides 7 are horizontally disposed in spaced overlying relation to the pile of sheets 1 and are operable as a guide and limit the height of the separated sheet above the pile. The guides further provide a relatively rigid platform for the underlapped sheets as they are fed into the pinch rolls of the sheet receiver.

Before discussing in detail the structure and functioning of the apparatus illustrated, the general cycle of operation will be briefly described. At the outset, the suction lifting members 3 are in contact with the rear edge portion 9 of top sheet 2 with hold downs 4 in a raised position, the suction lifting members 3 are raised thereby lifting the rear edge portion 9 of top sheet 2 and hold downs 4 are then lowered to secure the underlying sheet. As the lifting is commenced, air is supplied by blowing nozzles 6. The air is blown under the rear edge portion of top sheet 2 in order to facilitate separation of the top sheet 2 from the sheet pile and thereby assist in raising the top sheet 2.

As the suction lifting members 3 reach their upper position, suction forwarding members 5 engage the rear edge portion 9 of top sheet 2. The suction lifting members 3 then release the sheet 2. Suction forwarding members 5 then move forward in a horizontal plane and convey the top sheet 2 forwardly. Blowing nozzles 6 move forwardly with the suction forwarding members 5. The blowing nozzles 6, thus maintain a substantially constant position with respect to rear edge portion 9 of top sheet 2 during the forward movement of the suction forwarding members 5. With this arrangement, the underside of the top sheet 2 receives a constant, controlled supply of air as the sheet 2 is advanced.

During the initial raising and subsequent transport of the top sheet 2, the air supplied by nozzles 6 raises the top sheet 2 into contact with the underside of sheet guides 7. The sheet guides 7 limit the upward movement of the top sheet 2 and thereby controls the for-ward movement of the entire sheet. Ultimately, the front edge portion 8 of the top sheet 2 is delivered to sheet receiver 10, which in this instance consists of an endless belt 13 mounted on roller 12 and cooperating with a roller 11. The roller 11 serves as a pinch roll against belt 13 so that the front edge portion 8 of sheet 2 is engaged between roller 11 and belt 13 and conveyed to a sheet register device (not shown). The belt 13 and roller 11 are driven at the same peripheral speed as the forward speed of the suction forwarding members. The air nozzles 6 continue to supply air until the sheet is released by the suction forwarding members 5 and the sheet is engaged 'by the pinch roll 11 on belt 13.

DETAILED DESCRIPTION The apparatus for lifting the suction lifting members 3 is illustrated in detail in FIGURE 1. Each of the suction lifting members 3 has a suction foot 14 communicating with and secured to an overlying hollow tube 15. Air is exhausted from hollow tube 15 through tube 27 by air withdrawal means (not shown) such as a pump or the like in order to establish the required amount of suction at foot 14. Guide 16 has an upper portion 17 and a lower portion 18. These portions, 17 18 have aligned openings 20, 21 respectively, through which hollow tube extends. A sleeve 19 is secured to each hollow tube 15 intermediate the openings 26, 21. A coil spring 22 is disposed on hollow tube 15 between sleeve 19 and the upper portion 17 of guide 16 and urges the suction foot 14 downwardly. The sleeve 19 has a pin 23 that extends outwardly therefrom and through the open ended slot 24 of arm 25. Arm 25 is secured to shaft 26 which is journaled in support structure 45, and is adapted to rotate therewith.

The suction lifting members 3 are operated by means of cam 28 secured to a shaft 29 for rotation therewith. Arrn 25 has a stud 30 upon which is mounted a rotatable cam follower 31 that contacts cam 28. As cam 28 rotates arm 25 will be caused to rotate about shaft 26 so that the hollow tube 15 moves alternately upward and downward. Suction is applied when the suction lifting member 3 engages the top sheet 2 and suction is maintained until the suction lifting member 3 has raised top sheet 2 and the suction forwarding member 5 has engaged and is secured to the top sheet 2. It will be appreciated that by coo din g e rota ion o sha t 29 with th suction of the air withdrawal means (not shown) effective operation of the suction lifting member 3 is obtained.

The details of the sheet hold down apparatus 4 are shown in FIGURE 2. Hold down rod 32 has a foot 33 which rests upon and secures the rear edge 9 of the top sheet 2. During removal of top sheet 2, the hold down apparatus 4 secures the underlying sheet. Rod 32 is secured to mounting bracket 34 which has a cam groove 35 defined therein. A support member 36 has a pin 37 which passes through groove 35. The upper end of mounting bracket 34 is secured to arm 38 by means of rotatable fastener 39. Arm 38 is secured to shaft 40 and cam 41 is secured to shaft 42. Stud 43 which is on arm 38 has a rotatable cam follower 44 secured thereon.

As shaft 42 rotates, cam 41 establishes rotational movement of arm 38 about shaft 40 thereby causing foot 33 of hold down rod 32 to alternately move between the position shown by the solid line of FIGURE 2 and the position shown by the dotted line of the same figure. By coordinating rotation of shaft 42 with the operation of suction lifting member 3, appropriate hold down is eifected.

The foot 33 is in the down position in contact with the rear edge portion 9 of top sheet 2 until suction lifting member 3 has engaged the top sheet 2. The foot 33 is then raised to permit removal of the top sheet 2 from pile 1. As the top sheet 2 is raised, foot 33 is returned to the lower position to retain the underlying sheets in place while the feeder assembly conveys the top sheet 2 to the receiver 10. This procedure is repeated as each succeeding top sheet 2 is removed from sheet pile 1. In this fashion, inadvertent raising of a subsequent sheet by the air emerging from blowing nozzle 6 is avoided.

As is shown in FIGURES 1 and 3, supplemental h ld down devices in the form of rear pile guides 50 are provided along the rear edge of the pile in spaced relationship with respect to sheet hold down devices 4. The guide 50 has a body member 51 which has guide arm 52 and securing arm 53. The guide arm abuts against the rear vertical face of pile 1 and urges the edges of the sheets into alignment. In addition, leaf spring 54 is secured at one end to body member 51 and the other end is horizontally disposed on top of the rear end 9 of top sheet 2. After top sheet 2 has been raised, leaf spring 54 is disposed on top of the subsequent sheet. Leaf spring 54, therefore, assists in the hold down. In the form illustrated, guide 50 is anchored to rod 55 (FIGURE 3). As is shown in FIGURE 4, rod 55 is secured by brackets 88 which depend from arms 89. Double clamp 56 has a recess 57 into which rod 55 is placed and it is secured therein by means of thumb screw 58. A rod 59 is disposed in a lower recess of double clamp 56 and secured therein by a thumb screw 60. A vertically disposed channel 61 is rigidly secured to rod 59. Securing arm 53 is disposed within channel 61 and extends upwardly therefrom.

Also extending upwardly from channel 61 is a flanged member 62 to which is secured one end of coil spring 63, the other end of which is secured to rod 59. A screw passes through flange member 62 and arm 53 thereby securing these elements to each other and providing a somewhat resilient assembly. These guides 50, therefore, provide both hold down means for the rear sheet edges and alignment means for the upper portion of the rear vertical surface of the pile 1.

Once the rear edge 9 of the top sheet 2 has been raised in the fashion above described, suction forwarding members 5 engage the top sheet and the suction lifting members 3 release the top sheet. The top sheet 2 is then moved forwardly in a substantially horizontal path. Each suction forwarding member 5 has a foot 70 secured to and communicating with a hollow tube' 71 which is in turn connected with an air widthdrawal conduit 72. Conduit 72 communicates with an air withdrawal means (not shown) such as a pump or the like. The operation of the air withdrawal means for the suction forwarding members 5 is coordinated with the operation of the suction lifting members 3. The suction is applied to suction forwarding means 5 through foot 70 after the suction lifting members 3 have raised the top sheet 2 into position for transfer to suction forwarding members 5.

The application of suction to foot 70 does not terminate until the top sheet 2 has been conveyed by members 5 and is received by sheet receiver 10. During this horizontal movement of the top sheet 2, the suction forwarding members 5 move from the position indicated by solid lines in FIGURE 1 to that indicated by the dotted lines in the same figure. Each member 5 is secured to a support member 73. As is shown in FIGURE 4, support member 73 is mounted on shaft 85 which is in turn secured by brackets 86 depending from arms 87. Referring to FIGURE 1, each support member 73 is secured rotatably to a pair of upwardly extending arms 74, 75 which are in turn secured to shafts 76, 77 respectively. Arm 75 has a stud 78 on which is mounted a cam follower 79. Forwarding cam 80 is secured to shaft 29 and engages cam follower 79. Rotation of shaft 29 therefore, rotates cam 28 thereby causing movement of suction lifting members 3 and also causing rotation of cam 80 which in turn causes movement of suction forwarding members 5 between the two positions indicated in FIGURE 1.

It will therefore, be appreciated that by coordinating rotation of shaft 29 and shaft 42, the movement of suction lifting members 3, sheet hold down members 4, and suction forwarding members 5 is coordinated. The operation of the air removal means for the lifting members 3 and forwarding members 5 is coordinated with the movement of the respective members by any conventional means such as air valves or pumps operating responsively to one or more cams.

Having described the structural details and operation of the

suction transporting members

3 and 5 and hold down and

guide members

4, 50, the blowing nozzles 6 will now be considered in greater detail. Each blowing nozzle 6 is secured to and communicates with a flexible air conduit or hose 90. A suitable air supply means (not shown) communicates with hose 90. The air supply means conveniently has control means (not shown) adapted to provide air under suitable pressure and in suitable volume through hose 90 and out of nozzle 6 at the desired times as will be described hereinafter.

As has been indicated above, it is desirable to provide a stream of air under the top sheet 2 after lifting has been initiated. It is necessary to maintain this air flow until the top sheet 2 is released from the feeder. In the past, air blowing nozzles have directed a portion of the air above the sheet, thereby resisting the desired upward movement of the sheet and causing fluttering of the sheet. The apparatus of this invention has effectively solved this problem. Applicants apparatus maintains substantially the same distance between the rear edge 9 of the top sheet 2 and the blower nozzle 6 as the sheet 2 moves along the feeder. It therefore provides the top sheet with an effective, constant air stream which will impinge upon the underside of the sheet and will provide assistance in retaining the sheet in substantially flat elevated position.

As has been indicated above, each blower nozzle 6 is connected with air supply means by a flexible air conduit or hose 90 which permits freedom of movement of the nozzle 6 while retaining continuous operative air passageway. The substantially horizontally disposed nozzles are secured to support member 73 and are adapted to move therewith. In the form selected for illustration in FIGURE 1, a rigid shaft 64 is secured to nozzle 6 and support member 73 thereby connecting the two. As may be generally seen in FIGURE 4, if desired, blower nozzle 6 may be mounted in such fashion as to permit vertical adjustment thereof and precise control of the vertical spacing between the pile 1, suction forwarding means 5 and blower nozzle 6 may be obtained.

Suction forwarding members 5 are moved horizontally by means of cam causing movement of arm 75 which is transmitted to support member 73. Blower nozzle 6 which is secured to support member 73 will therefore move in the same direction and at the same speed as the suction forwarding members 5. The extended position of the blower nozzle 6 is indicated by the dotted lines in FIGURE 3. In so doing, the nozzle 6 will be maintained at a fixed distance from the rear edge 9 of the top sheet 2 as the sheet is moved horizontally and the air supply will be continuously delivered substantially completely to the underside of top sheet 2, thereby maintaining the sheet substantially fiat during horizontal transport.

Once the sheet has been released by the suction forwarding member 5 to the sheet receiver 16, support member 73 is returned to its original position thereby returning suction forwarding members 5 and blower nozzles 6 to their initial rearmost position. As in the preferred form of this invention, the blower nozzles 6 being secured to support member 73, there is no need to provide independent means for coordinating movement of the nozzles 6 and forwarding members 5.

While this invention facilitates improved horizontal transfer of top sheet 2, it should be noted that the blower nozzles 6 are always returned to an initial position from which it performs its other functions, i.e., assisting initial separation of the top sheet 2 from the underlying sheet during operation of the suction lifting members 3. The desirable features of mobility of the blower nozzles 6 of this invention, therefore, do not have any detrimental effect upon the stationary functions of the nozzles 6.

As has been indicated above, the feeder assembly of this invention provides a plurality of horizontally disposed sheet guides 7. These guides are disposed in spaced overlying relationship with respect to the pile 1 and are adapted to prevent undesirably high displacement of the leading end 8 of the sheet as a result of air received from the blower nozzles 6. Thus, even though the movement of the nozzles 6 produce a continuous air stream of substantial magnitude, the guides 7 prevent excessive upward displacement of the sheet. In the preferred form, the

guides 7 are telescoping with arm 7a adapted to extend into and retract from tubular arm 7b. Such guides may be quickly adjusted to handle various lengths of sheet. This is important as conventional printing presses and similar equipment are normally designed to operate upon a number of sheets of a number of sizes.

Another feature of this invention is the provision of support for guides 7 at both ends thereof in order to rigidify the support by eliminating the cantilevering present in conventional supports. As is conventional, the rear end portion 7b of guides 7 may be secured to rod 55. As illustrated in FIGURE 4, the rear end portion 7b has a two piece mounting bracket 94 which is secured to rod 55 by suitable fasteners, such as

bolts

95, 96. In addition, this invention provides rigidifying supports 10% at the opposite end of guides 7. An upturned end portion 70 of guide 7 passes through opening 103 in support and is secured therein by screw 104. Support 100 is secured to shaft 101 by means of screw 102. In this fashion, support of guides 7 at both ends is effected while providing the desired adjustability of guide length and means for securing the guides 7 at the desired length.

While it forms no part of this invention and, therefore, has not been illustrated, it is contemplated that suitable means for periodically elevating pile 1 as the level of the top sheet 2 moves below a desired point, may be provided. These means are conventional and need not be described in detail herein.

Where it is contemplated that the feeder will be employed with sheets of varying lengths, the feeder assembly may be mounted so as to permit relative movement between the operative feeder assembly and the sheet receiver to adjust for the length of sheet to be fed.

In operation of the preferred form of the feeder assembly of this invention, the guides 7 are adjusted to the desired length corresponding to the sheet size. The sheet pile 1 is positioned to place the top sheet 2 at the desired level. As the detailed operation of each of the components of the apparatus has been described above, only the sequence of operation will be discussed in the following summary. The suction lifting members 3 are moved downwardly into securing engagement with the rear end 9 of top sheet 2. The sheet hold down elements 4 are momentarily raised to facilitate raising of the suction lifting members 3 with the rear edge of the top sheet 2 secured thereto and then the hold down elements 4 moved downwardly to secure the subsequent underlying sheet. During the raising of top sheet 2, leaf springs 54 resiliently yield to permit removal of the top sheet 2 and immediately return to restrain the edge of the subsequent underlying sheet. As the top sheet 2 is raised, blowing nozzle 6 provides an air stream which moves under top sheet 2 and facilitates separation thereof from the subsequent sheets. When the suction lifting members 3 reach the upper limit of their travel, the top sheet 2 is engaged by suction forwarding members 5 and suction lifting members 3 release their engagement of the top sheet 2. The top sheet 2 is then conveyed in a substantially horizontal path by suction forwarding members 5. During this movement, blowing nozzles 6 move in the same direction and at the same rate of speed as the suction forwarding members 5. Blowing nozzles 6 continue to provide an air stream which is substantially completely directed toward the underside of top sheet 2, thereby flattening the sheet against the underside of extensible guides 7. The top sheet 2 is released by the suction forwarding members 5 after entry of sheet 2 into sheet receiver is initiated, at which time the air stream emerging from blower nozzles 6 may be terminated. The suction forwarding means 5 and blowing nozzle 6 are then returned to their initial positions and the sequence of operation is repeated.

While for purposes of illustration the means for coordinating the respective movements of the suction lifting members, suction forwarding members and hold down members have been shown to be cam operated levers, it will be appreciated by those skilled in the art that other coordinating means are suitable and may be employed in lieu of or in addition to those selected for purposes of illustration.

It will be appreciated that for clarity of discussion reference has been made to transfer of the top sheets from the suction forwarding members 5 directly to a sheet receiver 10 without mention of the relative spacing of the sheets. The feeder assembly of this invention is of primary value in so-called stream feeding. In this type of feeding, the lower rear portion of a leading sheet is in frictional engagement with the upper leading edge of a trailing sheet. This arrangement of sheets facilitates smooth, continuous feeding.

According to the provisions of the patent statutes, we have explained the principle, preferred construction, and

mode of operation of my invention and have illustrated 60 and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A sheet feeder assembly comprising,

a pile of sheets,

a movable suction means for engaging the top sheet adjacent the rear edge,

means for moving said movable suction means in a substantially horizontal path and advancing said top sheet,

blowing means for blowing air between said top sheet and underlying sheet to maintain separation of said top sheet from said underlying sheets, and

means connecting said blowing means to said suction means so that said blowing means moves with said suction means at substantially the same speed as said suction means. 2. The sheet feeder assembly of claim 1 wherein, said blowing means has at least one blowing nozzle and a flexible air supply conduit, and

said assembly has a plurality of elongated horizontal guide means disposed in spaced overlying relationship with respect to said pile adapted to limit the extent. of upward movement of said top sheet.

3. The sheet feeder assembly of claim 2 wherein,

said guide means have horizontally extensible and retractable arms and said guide means have supporting means disposed at both ends.

4. The sheet feeder assembly of claim 2 wherein,

said suction means has at least one vertically reciproeating suction member adapted to secure and raise the top sheet of said pile and at least one horizontally reciprocating suction member adapted to secure said raised top sheet and move said top sheet in a substantially horizontal path,

hold down means for securing sheets on said pile, and

said blowing means adapted to blow air under said top sheet substantially uniformly and continuously until said sheet is released by said horizontally reciprocating suction member.

5. The sheet feeder assembly of claim 4 wherein,

each of said horizontally reciprocating suction members is secured to a supporting member adapted for horizontal reciprocating movement and,

each of said supporting members having a blowing nozzle secured thereto and movable therewith.

6. The sheet feeder assembly of claim 5 including means for vertically adjusting the position of said blowing nozzle with respect to said elongate supporting memher.

7. The sheet feeder assembly of claim 5 wherein, said coordinating means includes a first cam activated lever system for moving said vertically reciprocating suction member and a second cam activated lever system :for moving said supporting member, at least some of said hold down means adapted to be alternately moved upward to release said top sheet 5 and downward to secure said subsequent sheets with said movement being regulated by a third cam activated lever system.

References Cited UNITED STATES PATENTS 2,389,480 11/1945 Baker 27126 2,901,249 8/ 1959 Dexter 27126 FOREIGN PATENTS 949,325 2/ 1964 Great Britain. 273,273 3/1964 Great Britain.

RICHARD E. AEGERTER, Primary Examiner