US3459351A

US3459351A - Method and apparatus for tensioning a moving strip

Info

Publication number: US3459351A
Application number: US670707A
Authority: US
Inventors: Max H Bursk
Original assignee: WILSON LEE ENG CO Inc
Current assignee: WILSON LEE ENG CO Inc
Priority date: 1967-09-26
Filing date: 1967-09-26
Publication date: 1969-08-05
Anticipated expiration: 1986-08-05

Description

M. H. BURSK Aug. 5, 1W9

METHOD AND APPARATUS FOR TENSIONING A MOVING STRIP Filed Sept, 26. 1967 6 Sheets-Sheet '1 INVENTOR. MAX H. 5095K Y W,M

A T roe/vim.

METHOD AND APPARATUS FOR TBNSIONING A MOVING STRIP Filed Sept. 26. 1967 M. H. BURSK Aug. 5, 1969 6 Sheets-Sheet 2 Il'nmullllhm a m 2 @m m 1 A Mn 3 W I'lIlIIlII" S- 1959 r M. H. BURSK 3,459,135!

METHOD AND APPARATUS FOR TENSIONING A MOVING STRIP F'iIe d Se t. 26. 19s? s Sheets-Sheet 3 N v Q N v INVENTOR. Q Q MAX H. 50am T j BY K, i

N N M sm ATTORNEYS,

Allg- 5, 1969 M. H. BURSK 3,459,851

METHOD AND APPARATUS FOR TENSIONING A MOVING STRIP Filed Sept. 26, 1967 I, s Sheets-Sheet 4 fi/ 103 ll l 105- E; T- J /06 i n I 7/ 60 L 95 l a! if 77 76 Z 5 76 v w 32 Z 3 H ll INVENTOR.

un; H MAX A. 50mm I1 I BYZ a l l u w A m 6 Sheets-Sheet 5 M. H. BURSK METHOD AND APPARATUS FOR TENSIONING A MOVING STRIP Aug. 5, 1969 INVENTOR. M X A! 019.57?

M, W M w G;

ATTORNEYS.

' Filedse pt. 26. 1967 United States Patent- 3,459,351 METHOD AND APPARATUS FOR TENSIONING A MOVING STRIP Max H. Bursk, North Olmsted, Ohio, assignor to Wilson Lee Engineering Company, Inc., Cleveland, Ohio, a corporation of Ohio Filed Sept. 26, 1967, Ser. No. 670,707 Int. Cl. B65h 23/18, 23/08 US. Cl. 226-39 14 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for applying a pulling or tensioning force to a moving strip or web, such as sheet steel for example, either in the direction of travel of the strip or opposite to the direction of travel. A vacuum system is used in cooperation with moving belts to apply the tensioning force.

Background of the invention The handling of elongated strip material during processing requires special consideration when the strip is initially stored in coil form. The coils of strip material, such as webs of sheet steel, nonferrous metals, paper, plastic film, cloth and the like, are often wound on reels or mandrels between processing operations and the strip is fed into a processing line by means of pinch rolls, conveyors, or the like after which it is recoiled for further handling. Control of the strip as it translates through the processing line is frequently best accomplished by keeping the strip under tension from the pay-off reel to the winding reel.

In many applications it has been difficult to keep the strip under the desired tension due to such problems as the feeding out of free loops of the strip where transient variations in the speed of translation occur and the paying off or feeding of the strip from a free position or a loose or open coil. One such situation, where annealed steel strip must be fed from an open coil in the vertical on edge position to a flat horizontal condition for feeding through a temper mill, requires that the strip be twisted 90 between the open coil and the temper mill. In these and other applications it is both necessary and advantageous to have the strip under tension to help guide the strip and to provide desired back tension.

Existing apparatus generally employs bridle rolls or pinch rolls to develop the back tension. Bridle rolls require that the strip be passed around one roll for at least 180 and then passed around another parallel roll with a reverse bend for at least 180 with resulting danger of coil breaks. Pinch rolls, it effective as a tension creating means, may also change the physical condition of the strip in an undesired manner.

The method and apparatus of the present invention overcome the difficulties indicated above and afford other features and advantages not obtainable from the prior art.

Summary of the invention It is among the objects of the invention to develop tension in a moving strip being fed to or removed from a processing unit.

Another object of the invention is to synchronize the speed of a moving strip so that there is no relative movement between the strip and those parts of the tensioning apparatus which convey the strip to or from the processing unit.

Patented Aug. 5, 1969 These and other objects are accomplished through a method and apparatus including, as a part of the apparatus, an endless main belt driven in a path of travel which includes an elongated span parallel to the direction of travel of the strip, the belt portion moving across the span being adapted to engage the adjacent surface of the moving strip. The main belt has spaced transverse grooves formed in the outer surface thereof which extend intermediate the side edges of the belt and may extend beyond the side edges of the strip moving across the span, depending upon the width of the strip being handled. The main belt also has openings formed therein which are spaced longitudinally around its perimeter and which are located in the grooves. Cooperating with the main belt are one or more endless sealing belts adapted for location with a moving portion thereof adjacent and in simultaneous parallel motion with the portion of the main belt moving across the span, the sealing belt being adapted to seal the transverse grooves in the portion of the main belt between the edges of the moving strip and the sides of the strip engaging span of the main belt. A vacuum system is provided contiguously with the portion of the main belt which extends across the span and is adapted to communicate with openings through the belt for evacuating atmosphere from the transverse grooves therein while the belt is in motion. The strip tensioning force is applied to the main belt by means of a suitable dynamoelectric device or the like.

The apparatus may include a mechanism for pivoting the endless sealing belt into and out of sealing engagement with the span of the main belt while the strip is moved along with the span portion of the main belt.

According to one form of the invention two endless sealing belts are utilized, one located on each side of the main belt in a fashion whereby the two sealing belts seal the opposite ends of the transverse grooves between the sides of the main belt and the edges of the strip.

According to another aspect of the invention a mechanism is provided for detecting a variation between the speed of the strip passing through the apparatus and the surface speed of one of the belts in the span (i.e., slippage) and for using this variation, if detected, for adjusting the tensioning force exerted by the belts on the strip to reduce the slippage.

Other objects, uses and advantages will be apparent from the following detailed description and drawings which illustrate a preferred form of the invention and wherein like parts are indicated by like numerals.

Brief description of the drawings FIGURE 1 is a side elevational view of the apparatus embodying the invention and indicating in dash lines the upward limit of the angular adjustment thereof. Also shown in dot and dash lines is the position of the sealing belt unit when the apparatus is open to receive or thread a strip therethrough;

FIGURES 2 and 2A show a plan view of the apparatus of FIGURE 1, FIGURE 2A being an extension of FIG- URE 2 on the right hand side thereof, with parts broken away for the purpose of illustration;

FIGURE 3 is an end elevational view of the apparatus of FIGURE 1;

FIGURE 4 is a fragmentary end elevational view similar to FIGURE 3 with parts broken away and shown in section;

FIGURE 5 is a fragmentary sectional view taken on the line 5-5 of FIGURE 1;

FIGURE 6 is a fragmentary sectional view on an enlarged scale taken on the line 6--6 of FIGURE 1;

FIGURE 7 is a fragmentary elevational view on an enlarged scale illustrating the drive mechanism for the upper sealing belts, taken substantially on line 77 of FIG- URE 3;

FIGURE 8 is a fragmentary sectional view on an enlarged scale taken on the line 8-8 of FIGURE 2; and

FIGURE 9 is a fragmentary sectional view on an enlarged scale taken on the line 9-9 of FIGURE 2.

Description of the illustrated embodiment Referring more particularly to the drawings there is shown a tensioning apparatus A embodying the invention and adapted to exert a tensioning force on a strip B of sheet steel being supplied from a coil C as best shown in FIGURES 1, 2 and 3. The apparatus includes a base 10 and a table 11 mounted for horizontal movement on the base 10 about a vertical pivot pin 12 and resting on bearing

plates

13, 14, 15 and 16. A hydraulic cylinder 18 located at the far right-hand end of the base 10 and table 11 as viewed in FIGURE 2 serves to pivot the table 11 in a horizontal plane about the pivot pin 12 and locate the apparatus at a desired angular disposition for receiving the strip B from the coil C, the cylinder 18 being pivotally connected at one end to a bracket 19 mounted on the frame 10 and the piston rod 18 extending from its other end and being pivotally connected to a bracket 20 mounted on the table 11.

Mounted in pillow blocks 21 and 22 on the table 11 is a shaft 23 which is connected to a reduction unit in a gear box 24 through a coupling 25. The reduction unit in the gear box 24 is connected to a dynamoelectric machine 26 through a flexible coupling 27. The machine 26 may be either a drive motor for rotating shaft 23 when the apparatus is used to exert a moving force on the stri or an electrical brake means when the apparatus is used to exert a hold-back or retarding tension on strip being advanced by other means. It will be understood that different means for developing tension or drag on the strip may also be used, such for example as a fluid operated slip brake, an eddy current clutch or a hydraulic pump acting against a hydraulic relief valve.

Pivotably mounted on hearing

sleeves

30 and 31 on the shaft 23 are side frame members 32 and 33 (see FIG- URE 4) which may be moved about the axis of the shaft 23 to the desired tilt angle between the horizontal position shown in solid lines in FIGURE 1 and the upwardly tilted position shown in dash lines. The position of the

members

32 and 33 is adjusted by means of

hydraulic cylinders

34 and 35 pivotally connected at one end to the

frame members

32 and 33 respectively and at their other ends to the table 11 as best shown in FIGURES 1, 3 and 6.

Keyed to the shaft 23 (FIGURE 4) is a head pulley 36 which drives a main belt 37 extending between the head pulley 36 and a tail pulley 38 carried by an idler shaft 39 mounted in bearing blocks 40 and 41 secured to the

frame members

32 and 33 respectively.

The upwardly facing portion of the main belt 37 defines an elongated span extending between the head pulley 36 and tail pulley 38 and is adapted to support the strip B during its travel across the span. The belt portion moving across the span is adapted frictionally to engage the adjacent under-surface of the moving strip B and is supported from below by a series of transverse idler rollers 44 journaled at their ends in the

frame members

32 and 33.

Suitable tension is maintained in the main belt 37 by means of a tension roller 46 (FIGURES 1 and 5) journaled in opposite arms of a yoke member 47 which is slidably received in a transverse member 48, U-shaped in cross-section, which extends between and is secured at its end to the frame members 32 and 33 (see FIGURES 1 and 5 Tension is applied to the main belt 37 by means of a hydraulic cylinder 49 mounted on the transverse member 47.

Formed on the inner surface of the main belt 37 are two longitudinal

parallel ribs

50 and 51 which are received in matching

annular grooves

52 and 53 in the head pulley 36 as well as

annular grooves

55 and 56 in the tail pulley 38 and grooves 57 and 58 in the idler rolls 44 (FIGURES 2 and 8). Formed in the outer face of the main belt 37, and uniformly spaced apart along its entire length, are spaced transverse grooves 60 which extend intermediate its side edges (FIGURE 2) and serve a purpose to be described in detail below.

Extending longitudinally across the span of the main belt 37 between the head pulley 36 and tail pulley 38 is an elongated vaGuum box 61 from which atmosphere is evacuated by means of a pump 62, the box 61 having openings 63 formed in the upwardly facing side thereof (FIGURES l and 8). Secured to the top of the vacuum box 61 is a belt engaging slab 64, preferably formed of a relatively soft nonabrasive material such as wood, which has openings 65 formed therein to match the openings 63. Extending along the top of the slab 64 are longitudinal slots 66 located along the lines defined by the rows of openings 65.

Formed in the lateral grooves 60 of the main belt 37 are openings 70 arranged in two parallel longitudinal rows around the periphery of the belt and located over the slots 66 in the stab 64 when the main belt passes across the span between the

pulleys

36 and 38. Accordingly, the vacuum produced in the vacuum box 61 is effective in the lateral grooves 60 in the main belt 37 as they pass over the vacuum box 61 to provide effective frictional engagement between the main belt and the strip B as they travel across the span.

Pivotally connected to the

side frame members

32 and 33 are two

upper frame members

70 and 71. Mounted below the rearward (to the left in FIGURE 1) end portions of the

upper frame members

70 and 71 are bearing

plates

72 and 73 which are rotatably mounted on bearing

sleeves

74 and 75 secured to the main frame members 32 and 33 (FIGURES 3 and 9). The

side frame members

70 and 71 are pivotally supported on the bearing

sleeves

74 and 75 relative to the

main frame members

32 and 33 and are movable between a closed position shown in dash lines and an open position shown in dot and dash lines in FIGURE 1 by means of

hydraulic cylinders

76 and 77. The

cylinders

76 and 77 are pivotally mounted in the

main frame members

32 and 33 respectively (FIGURE 6) by means of binge pins 78 and 79 and the pistons thereof are pivotally connected to the

members

70 and 71 respectively by means of hinge pins 80 and 81. Rotatably mounted between the rearward ends of

upper frame members

70 and 71 on a transverse shaft 84 are sealing belt head pulleys 85 and 86 (FIGURES 2, 3 and 4). Mounted at the opposite ends of the

frame members

70 and 71 are sealing belt tail pulleys 87 and 88 mounted on a shaft 89 journaled in bearing

brackets

91 and 92 on the

members

70 and 71.

Sealing

belts

93 and 94 are looped around the cooperating head and tail pulleys 85 and 87, and 86 and 88 respectively with their bottom reaches disposed directly above and adapted for simultaneous parallel motion with the top reach of the main belt 37 as it moves across the span between the

pulleys

36 and 38. The sealing

belts

93 and 94 engage the outer side portions of the main belt 37 and overlie the ends of the lateral grooves 60 as well as the marginal edge portions of the strip B located between the main belt 37 and the sealing

belts

93 and 94. Thus the sealing

belts

93 and 94 serve to seal the lateral grooves 60 between the edges of the strip B and the side portions of the belt 37 and prevent the entry of atmosphere into grooves 60 even though the width of strip being handled may vary as will be explained later.

Accordingly atmospheric pressure is effective, due to the vacuum applied to the grooves 60, to press the strip B into firm frictional engagement with the main belt 37 and also to press the sealing

belts

93 and 94 into frictional engagement with the marginal portions of the top surface of the strip B.

Tension in the

belts

93 and 94 is maintained by means of

tension rollers

95 and 96 which depress the

belts

93 and 94 between the head pulleys 85 and 86 and idler rolls 97 and 98 (FIGURE 1). The

belts

93 and 94 have central

longitudinal ribs

99 and 100 respectively, which are received in corresponding annular grooves 85 and 86' formed in the head pulleys 85 and 86 respectively as well as corresponding grooves formed in the tail pulleys 87 and 88,

tension rollers

95 and 96, and idler rolls 97 and 98. The

tension rollers

95 and 96 are operated by means of

hydraulic cylinders

101 and 102 respectively mounted on a crossbeam 103 secured to the upper frame members '70 and 71. The

rollers

95 and 96 are carried in

yoke members

105 and 106 slidably mounted in the crossbeam 103 and connected to the pistons of the

cylinders

101 and 102.

The shaft 84 (FIGURES 2, 4 and 7) is journaled in bearing

blocks

109 and 110 mounted in the

frame members

70 and 71. A pulley 111 mounted on one end of the shaft 84 is driven by a belt 112 from another pulley 113 mounted on a shaft 114 which is concentric with the bearing sleeves 74 and 75 (FIGURE 9).

Mounted on the shaft 114 adjacent the pulley 113 is a gear 116 (FIGURES 7 and 9) which meshes with and is driven by a gear 117 (FIGURE 7) secured to the end of the drive shaft 23 which drives the main belt head pulley 36. Accordingly the sealing belt 'head pulleys 85 and 86 are driven by the same drive as the main belt head pulley 36 and the dimensional relationships between the

gears

116 and 117 and

pulleys

111 and 113 are such that the surface speeds of the rolls are matched to one another, or more importantly that the lineal speeds of the reaches of the main belt 37 and sealing

belts

93 and 94, extending between the head and tail pulleys, are the same.

The shaft 114 (FIGURE 9) is journaled in

bearings

118 and 119 mounted in the bearing sleeve 74. As indicated above, the axis of the shaft 114 is the same as the axis for the bearing

sleeves

74 and 75 about which the

upper frame members

70 and 71 pivot between their open and closed positions. Accordingly pivotal movement of the

upper frame members

70 and 71 about their axes to lift or lower the sealing

belts

93 and 94 may be done without affecting the drive of the belts through the

pulleys

85 and 86.

It will be apparent that the torque applied to the main belt head pulley 36 should be so limited that the frictional force between the strip B and the

belts

37, 93 and 94 will be sufificient to prevent slippage due to the tension or drag produced by the dynamoelectric machine 26 or other mechanism as such slippage between the strip and the belts might cause the strip B to be scratched or marred.

In order to prevent this a slip sensing feed-back mechanism is provided to reduce the tension or drag whenever slippage occurs. This mechanism, best shown in FIG- URES 2, 3 and 9, includes a shaft 120 journaled coaxially with the shaft 114 at one end in a bearing block 121 and at the other end in a manner to be described below. A bracket 122, pivotally mounted on shaft 120 (FIG- URE 3), carries a strip engaging rubber surfaced roller 124 which is positioned to engage the surface of the strip B as it enters the tensioning unit A. The roller 124 is secured to a shaft 125 journaled in the bracket 122. Also secured to the shaft 125 is a gear 126 which meshes with and drives another gear 127 keyed to the shaft 120. Accordingly the shaft 120 is driven by roller 124 and its speed of rotation is determined by the speed of the strip B entering the unit A.

Mounted on the shaft 120 at the right-hand end thereof as viewed in FIGURE 9 is a sleeve 130 which is journaled in

bearings

131 and 132 mounted in the bearing sleeve 75. Keyed to the sleeve 130 is a roller 133 which as is best shown in FIGURE 2, is adapted to engage the surface of the main belt 37. Accordingly, by virtue of the gearing described above, the shaft turns in a direction opposite to that of the sleeve 130.

The sleeve carries and drives a bevel gear 134 forming a part of a differential unit 135, the shaft 120 carrying and driving a coaxial bevel gear 136. So long as the speeds of the

bevel gears

134 and 136 are the same (which is the case when no slippage occurs between the belts and the strip B) the differential unit 135 will remain stationary. When slippage occurs, however, the differential in speed between the

bevel gears

134 and 136 will cause rotation of the differential cage 137 which operates a current regulator rheostat 138 (FIGURE 9). The rheostat 138 adjusts the current of the dynamoelectric machine 26 to reduce the tension or drag induced by the unit to a level at which no slippage will occur.

In some instances metal strip is rolled with a camber or shape in which one side of the strip is longer than the other resulting in a strip that would form a semicircle if stretched out far enough on a fiat plane. Accordingly it is desirable that some means he provided to guide the strip through the unit in a manner which will compensate for this camber. The necessary adjustment is made by turning the table 11 about the pivot pin 12, using the cylinder 18, to an appropriate angular position relative to the coil C (see FIGURE 1).

An edge guide 140 (FIGURE 2) is mounted at the exit end of the unit A and is secured to an external fixed support for keeping the strip aligned with the center line of the unit A. The guide 140 is mounted on a threaded rod 141 so that it-may be adjusted to accommodate different widths of strip. I

If desired a detecting device, such as photocell or air stream, may be mounted at the exit end of the unit in a position such that the edge of the strip must pass through the device. Whenever the strip deviates from the desired path of travel the detecting device feeds a signal to the hydraulic control unit which operates the hydraulic cylinder 18. This causes the cylinder to operate in a manner tending to return the centerline of the unit A toward the centerline of the strip at the exit end of the unit.

Operation In the operation of the preferred embodiment shown and described herein, after a coil C of metal strip B is positioned forfeeding into the input end of the tensioning apparatus A, the table 11 is pivoted on the base 10 to the desired location using the hydraulic cylinder 18. Also the

frame members

32 and 33 are adjusted to the desired angle of tilt using the

hydraulic cylinders

34 and 35.

To permit the initial positioning ofthe end of the strip B between the main belt 37 and sealing

belts

93 and 94, the

upper frame members

70 and 71 are pivoted upward away from the

main frame members

32 and 33 using the hydraulic cylinders 76 and 77 (see dot and dash line position of member 71 in FIGURE 1). The end of the strip B is drawn through the apparatus A and placed in position at the exit end thereof for feeding into further processing equipment such as a temper mill. The edge guide 140 is adjusted to the right-hand edge of the strip B as viewed in FIGURE 2.

The sealing

belts

93 and 94 are then lowered into sealing engagement with the top surface of the strip B and the main belt 37, and the vacuum pump 62 is actuated. Following this the dynamoelectric machine 26 is energized to drive the head pulleys 36 and 86 and thus cause the

belts

37, 93 and 94 to operate simultaneously and translate the strip B across the span. The belts are kept in firm frictional engagement with the strip as a result of the vacuum in the grooves 60 in the main belt 37.

Accordingly the strip B may be unwound from the coil C and fed at uniform speed to a temper mill or other processing unit. The unwinding of strip from the coil C will have no effect on the speed ortension of the strip as it exits the apparatus A and the strip may be advanced' Any slippage between the strip B and the belt 37 will be manifested by a difference in speed between the sensing

rollers

124 and 133. This differential results in rotation of the cage 137 of the differential unit 135 and corresponding adjustment of the rheostat 138. Thus the current or back drag of the dynamoelectric machine 26 will be appropriately increased or decreased to eliminate the slippage.

Although only one embodimentof the invention is illustrated and described it will be understood that variations and modifications may be made in the form and arrangement of the several parts or elements thereof without departing from the spirit of the invention.

I claim: v

1. Apparatus for applying tension 'force to a continuous moving strip of sheet material comprising, a main endless belt driven in a path of travel including an elongated span parallel to the direction of travel of said strip, the belt portion moving across said span being adapted to frictionally engage the adjacent surface of said moving strip, said main belt having spaced transverse grooves formed in the outer surface and extending intermediate the side edges thereof and having openings therein spaced longitudinally therearound and located in said grooves, an endless sealing belt means with a moving portion thereof supported adjacent to and for simultaneous parallel motion with said portion of said main belt as it moves across said span, said sealing belt means being adapted to seal said grooves in said belt portion between an edge of said strip and the ends of said grooves, evacuating means contiguous with the portion of said main endless belt extending across said span and communicating with said openings for evacuating atmosphere from said grooves through said openings while said main endless belt is in motion, and means for exerting a force on said main belt for applying a tension force on said strip.

2. Apparatus as defined in claim 1 wherein said main endless belt and said endless sealing belt means are driven simultaneously by a dynamoelectric machine.

3. Apparatus as defined in claim 1 including means for pivoting said endless sealing belt means into and out of sealing engagement with said span of said main endless belt and a strip.

4. Apparatus as defined in claim 1 including two endless sealing belts, one located at each side of said main endless belt, said sealing belts being adapted to seal the opposite ends of said grooves between said main endless belt and said strip.

5. Apparatus as defined in claim 1 wherein said evacuating means comprises a vacuum box mounted within said main endless belt and adapted to communicate with the said openings positioned in said span, and means for evacuating atmosphere from said vacuum box.

6. Apparatus as defined in claim 1 including means for detecting variation between the speed of a strip passing through said apparatus and the surface speed of one of said belts in said span, and means for adjusting the force exerted by said belts on said strip to reduce said variation.

7. Apparatus as defined in claim 6 wherein said means for detecting variation between the speed of a strip passing through said apparatus and the surface speed of one of said belts in said span comprises:

a strip engaging roller, a belt engaging roller, and a differential gear unit including:

a first bevel gear operatively connected to said strip engaging roller, and a second bevel gear operatively connected to said belt engaging roller for rotation normally opposite to the rotation of said first-bevel gear and at the same speed when said strip is moving at the same speed as said belt,

said differential unit being operatively connected to said means for adjusting the force exerted by said belts on said strip whereby said force is reduced in response to slippage between said strip and said main belt.

8. Apparatus as-defined' in claim 7 wherein said means for exerting a force on said main belt is a dynamoelectric machine and wherein said means for adjusting said force is a rheostat.

9. Apparatus as defined in claim 1 including means engageable with said belts in the reaches thereof opposite to said span for applying a tensioning force thereto.

10. Apparatus as defined in claim 9 wherein said means for applying a tensioning force to said belts comprises idler rollers movable by hydraulic cylinders in a direction perpendicular to the axes of said rollers into flexing engagement with said belts.

11. Apparatus as defined in claim 1 including transverse idler rollers engageable with said main belt in said span for supporting said main belt during movement across said span.

12. Apparatus for applying tension force to a continuously moving strip of sheet material comprising:

a main belt unit including a head pulley, a tail pulley and an endless main belt, said pulleys being adapted to move said belt in a path of travel including an elongated span parallel to the direction of travel of said strip, the belt portion moving across said span being adapted to frictionally engage the adjacent surface of said moving strip, said belt having spaced transverse grooves formed in the outer surface thereof and extending intermediate the side of said belt and-beyond the side edges of said moving strip, and having openings therein spaced longitudinally therearound and located in said grooves,

a sealing belt unit including a head pulley, a tail pulley aand an endless sealing belt, said sealing belt unit pulleys being adapted to move said sealing belt in a path of travel wherein a moving portion thereof is adjacent and in simultaneous parallel motion with said portion of said main belt moving across said span and adapted to seal said grooves in said belt portion between an edge of said strip and a side of said portion of said main belt in said span,

a vacuum box mounted within said main belt and adapted to communicate with the openings in said main belt which are located in the portion of said main belt moving across said span, means for evacuating-gas from said vacuum box, and

means for driving said belts while frictionally engaging said strip and for exerting a pulling force on said strip.

13. Apparatus as defined in claim 12 including means for pivoting said main belt unit and said sealing belt unit about the axis of said head pulley of said main belt unit to adjust the slope angle of said span.

14. Apparatus as defined in claim 12 including means for pivoting said main belt unit and said sealing belt unit about a vertical axis.

References Cited UNITED STATES PATENTS 3,140,030 7/1964 Stewart 226-- 3,198,517 8/1965 Martin 271-74 3,358,831 12/1967 Cothrell 271-74 X 3,389,908 6/1968 Martin 271-74 ALLEN N. KNOWLES, Primary Examiner US. Cl. X.R. 226-