US2718822A

US2718822A - Apparatus for making fibrous cement sheets

Info

Publication number: US2718822A
Application number: US267020A
Authority: US
Inventors: Magnani Alessandro
Original assignee: FLSmidth and Co AS
Current assignee: FLSmidth and Co AS
Priority date: 1952-01-18
Filing date: 1952-01-18
Publication date: 1955-09-27
Anticipated expiration: 1972-09-27

Description

Sept. 27, 1955 A. MAGNAN I APPARATUS FOR MAKING FIBROUS CEMENT SHEETS Filed Jan. 18, 1952 2 Sheets-Sheet l 32 flaw 7 w liwwm ATTO R N EYS Sept. 27, 1955 MAGNAN] 2,718,822

APPARATUS FOR MAKING FIBROUS CEMENT SHEETS Filed Jan. 18, 1952 2 Sheets-Sheet 2 a; 64 i r INVENTOR 45m M704; EZZWW ATTORREYS United Sttes Patent APPARATUS FUR MAKING FIBROUS CEMENT SHEETS Alessandro Magnani, Broni, Pavia, Italy, assignor of onehalf to F. L. Smidth & Co. A/S, Copenhagen, Denmark, a corporation of Denmark Application January 18, 1952, Serial No. 267,020

Claims. (Cl. 92-38) This invention relates to the manufacture of fibrous cement sheets, and is concerned more particularly with a novel apparatus for compressing and calendering such sheets to give them a smooth uniform surface.

Fibrous cement sheets are now commonly made by continuously feeding a pasty aqueous fibrous cement material to and distributing it upon a moving endless suction support, after which the material is formed and compressed, the excess water being drawn off through the support during the several operations. In the known methods, the formed material may be compressed by a rotating roller, which may be reciprocated in the plane of the layer of material, and, by rotating the roller with a surface speed greater than the rate of advance of the material, the layer of material may be subjected to a calendering action simultaneously with the removal of water therefrom. Heretofore, it has been difiicult to achieve satisfactory simultaneous compression and calendering of the sheet, since it is necessary, in order to produce a smooth, close surface on the sheet, that some water be present in the surface during calendering and the continuous suction eifect tends to reduce the amount of water below that required. The ditficulty referred to is enhanced as the thickness of the sheet increases, since the dewatering of such sheets requires stronger suction, which lessens the amount of water present in the surface of the sheet.

The present invention is, accordingly, directed to the provision of a novel apparatus for simultaneously calendering and compressing formed fibrous cement sheets, which is superior to prior apparatus used for the purpose, in that the sheets are given a smoother and more uniform surface.

In the operation of the new apparatus, the calendering and compressing is effected by means of an element, which is caused to move relatively to the sheet both in the plane of the sheet and at an angle to that plane. The movement of the element in the plane of the sheet is at a speed greater than that, at which the sheet is advanced, so the element smooths and calenders the surface of the sheet. The movement of the element at an angle to the plane of the sheet both compresses the sheet and forces to the surface the amount of water required for satisfactory ealendering.

One form of the new apparatus preferably includes an endless series of connected hollow boxes having pervious top surfaces, the series of boxes being encircled by a fabric belt. The boxes are supported, so that the series has a horozintal upper stretch and the boxes in this stretch are evacuated. The belt lies in contact with the tops of the boxes in the stretch and aqueous fibrous cement material is deposited on that portion of the belt. The deposited material is then formed into a sheet, from which excess water is removed by suction applied to the sheet through the boxes and belt. The simultaneous calendering and compressing operations are performed on the fibrous cement sheet after a part of the excess water has been removed therefrom, and, if desired, the suction applied to the portion of the sheet being calendered and compressed may be reduced or entirely cut off. The belt continues in its plane beyond the end of the horizontal upper stretch of the series of boxes and the portion of the belt beyond the stretch is maintained in position by a support. If desired, the calendering and compressing operation may be performed on the sheet in contact with the belt above the support therefor. When the separate support is employed, it is desirable to subject the belt to a dewatering action between the end of the upper stretch of the series of boxes and the support spaced therefrom. This facilitates the movement of the belt over the support, since an excessive Water content in the belt has been found to impede its movement.

The apparatus of the invention may be used to particular advantage in the production of thick sheets, which can be dewatered only by intense suction action. The apparatus may also be employed for other purposes as, for example, for establishing intimate contact between the sheet and granular material deposited over the surface thereof.

In the new apparatus, a ealendering and compressing element is mounted above the sheet and operated, so that it has a movement with a component parallel to the plane of the sheet and another component at an angle to that plane. It is desirable to mount the element for cyclical movement and, for this purpose, it may be mounted to rotate about the axis of a shaft, which is simultaneously moved toward and away from the suction support. The element is rotated with a surface speed different from that of the rate of advance of the sheet, in order that calendering action may be effected, and, preferably, the shaft is moved toward and away from the plane of the sheet a number of times during each rotation of the element about the axis of the shaft. The mounting for the element and the means for operating it in the manner described may take various forms, which will be illustrated and described in detail.

For a better understanding of the invention, reference may be made to the accompanying drawings, in which:

Fig. l is a view in side elevation with parts broken away of one form of the new apparatus for practicing the method of the invention;

Fig. 2 is a plan view with parts broken away of the apparatus of Fig. 1;

Fig. 3 is a fragmentary view in side elevation of a modified form of the apparatus;

Fig. 4 is a plan view of the apparatus shown in Fig. 3;

Fig. 5 is a sectional view on an enlarged scale on the line 55 of Fig. 1;

Fig. 6 is a sectional view similar to Fig. 5 of a modified form of the apparatus;

Fig. 7 is a sectional view on the line 77 of Fig. 6; and

Fig. 8 is a side elevational view of another form of the apparatus.

The apparatus shown in Fig. l is for use in the production of a longitudinally corrugated asbestos cement sheet of indefinite length, which is subsequently cut into units of the desired size. The apparatus comprises a framework 11 carrying bearings 12, in which rotate shafts 13, at least one of which is driven by a motor 14 through a speed reduction gear box 15. The shafts 13 have wheels 16 fast thereon, and an endless chain of connected ho}- low suction boxes 17 is trained about the wheels, the boxes having a length somewhat greater than the width of the sheet to be produced. The outer faces of the boxes are perforated and the boxes have slots in their under surfaces near their ends, the slots extending in the direction of travel of the chain.

The boxes in the upper horizontal stretch 18 of the chain are supported from beneath by a pair of suction chambers 19 mounted on the frame members and lying near the ends of the boxes in stretch 18. Each chamber has a longitudinal slot in its top registering with slots in the bottoms of boxes in the stretch and, in the construction shown, each chamber has an internal partition 21 subdividing it into two

sub-chambers

19a, 19b. The sub-chambers are connected by respective lines 22, 23 to a vacuum pump and line 23 leading to sub-chamber 19b contains a valve 24. On evacuation of the chambers 19, suction is applied to the boxes through the slots 20 in the tops of the chambers and the slots in the bottoms of the boxes. The chain of boxes in the lower stretch 25 is supported on rails 26 mounted on cross-beams 27 attached to the framework. In the operation of the apparatus, the chain of boxes advances in the direction of the arrow, Fig. l.

The chain of boxes is encircled by a belt 28 of waterpervious fabric, which is trained about rollers 29 and has an upper stretch 28a lying in contact with the tops of the boxes in the upper stretch 18 of the chain. Since the sheet produced is to have longitudinal corrugations, the outer perforated surfaces of the boxes are similarly corrugated and the upper stretch of the belt must be formed to fit the tops of the boxes in stretch 18. For this purpose, the belt leaving the upper roller 29 passes between upper and lower sets of rollers 30, 31 mounted in offset relation on

respective shafts

32, 33, the shafts lying sufficiently close together, so that the belt is folded to longitudinally corrugated form in passing between the rollers. The boxes in the stretch 18 of the chain and the belt in contact with the tops of the boxes form a suction support, which gives the lower face of the sheet its desired form and also dewaters the sheet.

Beyond the end of stretch 18 of the chain of boxes, the belt passes over a corrugated fixed support 34, at the end of which is an angle bar 35. The belt turns at right angles around bar 35 to lose contact abruptly with the under surface of sheet S and, after passing around the lower rollers 29, the belt is cleaned by a spray nozzle 36. The belt becomes flat on leaving bar 35 and remains fiat until it reaches rollers 30, 31.

The aqueous fibrous cement material is delivered from a source through a flexible hose 37 having a nozzle 38 to a distributing device generally designated 39, the device lying above the suction support. The device includes a frame made up of side plates 40, in which are mounted shafts 41 provided with flanged wheels 42 running on tracks 43 supported on the framework of the apparatus and lying on opposite sides of the upper stretch of the chain of boxes. Each track has end sections with horizontal top surfaces and a mid-section having a top surface inclined upwardly in the direction of travel of the chain of boxes and belt. The shafts 41 carry corrugated rollers 44 fast thereon, and one shaft carries a gear 45 engaged by a pinion 46 on the shaft of a motor 47 mounted on the frame of the device. The motor is of the reversing type and, during the operation of the device, it drives one pair of wheels 42 alternately in opposite directions, so that the device is reciprocated lengthwise of the rails 43.

The nozzle 38 extends through a slot in a fixed guide 48 attached to the chambers 19 and extending diagonally across the path of reciprocation of the distributing device 39. The nozzle also projects through a slot in a guide 49 mounted on the device and extending at right angles to the path of reciprocation of the device. As the device reciprocates, the nozzle is moved with it and is caused to reciprocate transversely of the path of travel of the device by the action of the guides. The fibrous cement material is deposited through the nozzle on the surface of the suction support between the rollers 44 and, as the distributing device reciprocates, the deposited material is distributed and formed into a corrugated sheet.

Beyond the distributing device, the sheet is preliminarily compressed by a corrugated roller 50 on a shaft 51 in carriage 52. The carriage is provided with a secand shaft 51a, and the shafts have flanged rollers 53 running on tracks 54 with horizontal top surfaces. A motor 55 is mounted on the carriage and a pinion 56 on the motor shaft meshes with a gear 57 fast on shaft 51. The motor is of the reversing type and so operated that the carriage is reciprocated on tracks 54 during the operation of the apparatus. Roller 50 bears on the sheet and compresses it.

A framework 58 supports a motor 59 driving a shaft 60 through a gear reduction box 61. The shaft 60 carries a pair of

pulleys

62, 63, which are connected by respective belts 64, to

pulleys

66, 67. Pulley 66 is fast on a shaft 68 having eccentric bushings 69 fast thereon, the bushings rotating in bearings 70 carried by the framework 58. A corrugated roller 71 is mounted for free rotation on bearings 72 on shaft 68 and pulley 67 encircles shaft 68 and is attached to one end of the roller. In the operation of the apparatus, the shaft 68 and the roller 71 are continuously rotated and the roller lies in contact with the fibrous cement sheet S on top of the suction support. The surface speed of the roller is greater than that of the sheet, so that the roller calen-r ders the sheet, and, because of the eccentric bushings 69 on the shaft 68, the rotation of the shaft causes the roller to move toward and away from the sheet and thereby intermittently compress the sheet. The compression of the sheet forces water to the surface of the sheet and such water facilities the calendering action of the roller on the sheet.

In the form of the apparatus shown in Fig. 1, the roller 71 acts on the sheet lying on the part of the suction support overlying the sub-chambers 19b. During the calendering and compressing action of roller 71, the sheet is subjected to a degree of suction controlled by the setting of valve 24. Preferably, the suction applied to the portion of the sheet being compressed and calendered is less intense than that applied to the sheet during its formation and preliminary compression, and, if desired, the suction may be wholly cut off from sub-chambers 19b.

The modified construction of the calendering and compressing device shown in Figs. 3 and 4 is the same as that above described but is mounted in such manner that the corrugated roller 71 corresponding to roller 71 acts on sheet S lying on belt 28 in contact with the fixed support 34'. Excess water is removed from the belt by a suction roller 73 engaging the under surface of the belt between the end of the suction support and the support 34'.

The modified construction of the calendering and compressing device shown in Figs. 6 and 7 includes a shaft 74, on which corrugated roller 75 is mounted for free rotation. A pinion 76 fast on the shaft meshes with a gear 77 fast on a shaft 78 supported in hearings in arms 79 pivotally mounted on shaft 74. Shaft 78 also carries a pinion 80 meshing with a gear 81 loosely encircling shaft 74 and secured to one end of roller 75. Shaft 74 has eccentric bushings, 82 fast thereon, the bushings being rotatable in fixed bearings 83 carried by supports 84. The arms 79 are connected by links 85 to supports 84. Shaft 74 carries a pulley 86 driven by a motor and gear reduction box (not shown) through a belt 87.

The modified calendering and compressing device shown in Fig. 8 includes a corrugated roller 88 acting on sheet S and supported for rotation in the lower ends of rods 89, the upper ends of which are pivotally supported on a shaft 90 urged downwardly by compression springs 91 acting against a fixed abutment 92. The rods 89 are oscillated by connecting rods 93 attached to respective crank discs 94. Roller 88 is provided with a pulley 95 connected by a belt 96 to a pulley 97 on shaft 90. Shaft 90 carries another pulley 98 connected by belt 99 to one of the crank discs 94. The discs are fast on a shaft carrying a pulley 100 connected by a belt 101 to a pulley on the shaft of a motor 102.

In the operation of the apparatus described, the aqueous fibrous cement material is deposited on the suction support within the distributing device 39 and the latter: reciprocates lengthwise of the direction. of travelof the suction support to distribute the material and form it into a corrugated sheet. The 'sheet is advanced to the preliminary compressing roller and is then carried along with the support and subjected to simultaneous calendering and compressing operations performed by the roller. As the roller rotates at a higher surface speed than the sheet, it smooths the latter and the movement of the shaft, on which the roller is mounted, causes the roller to compress the sheet intermittently to bring water to the surface thereof to facilitate the calendering operation.

In the construction shown in Figs. 1 and 2, the sheet may be dewatered by suction applied through sub-chambers 1%, while the calendering and compressing operations are carried on, and, preferably, the suction so applied is less than that applied to the sheet elsewhere. In the construction shown in Fig. 2, the sheet is supported on the stationary support 34', while being simultaneously calendered and compressed, and no dewatering action takes place during these operations.

The calendering and compressing roller 75 in the Fig. 6 construction functions in the same manner as

rollers

71, 71 in the constructions shown in Figs. 1 and 3, in that the axis of shaft 74, on which roller 75 rotates, is caused to describe a circle during the rotation of the roller. The roller is, accordingly, moved toward and away from the sheet repeatedly to subject the latter to compression. In the forms of the apparatus shown in Figs. 1, 3, and 6, the rotational speed of the shaft is preferably much greater than that of the roller, as, for example, the shaft may rotate at 300 R. P. M. and the roller at 30 R. P. M., so that the roller moves toward and away from the sheet ten times during each rotation of the roller. Such repeated compressing operations during calendering are preferred.

In the construction shown in Fig. 8, the calendering and compressing roller 88 has a pendulum movement, so that the pressure exerted by it is distributed over a larger area of the sheet. This facilitates dewatering of the sheet by suction and produces a compact sheet of minimum water content.

In the form of the apparatus shown in Figs. 3 and 4, the calendering and compressing roller 71' acts on the sheet lying on the belt above the stationary support 34 and the sheet is not being subjected to dewatering by suction during the calendering and compressing operations. It will be apparent, that the support 34 may, if desired, be replaced by a suction roller or by a movable support with or without a suction system.

The apparatus illustrated produces longitudinally corrugated sheets and, accordingly, the distributing, compressing, and calendering and compressing rollers and the tops of the boxes and of the fixed support are all corrugated. Also, the belt is shaped to corrugated form, so that it will lie in extended contact with the tops of the boxes in the upper stretch of the chain. When the apparatus is to be used for producing flat sheets, the surfaces of the several parts of the apparatus mentioned are either fiat or cylindrical and the rollers for shaping the belt are omitted.

I claim:

1. An apparatus for the manufacture of fibrous cement sheets, which comprises an endless continuously movable hollow support having a horizontal upper stretch, an endless water-pervious belt encircling the support and lying in contact with the top of the support in said stretch, means for depositing aqueous fibrous cement material upon the portion of the belt in contact with the support, means for forming the deposited material into a sheet, means for moving the support and belt to advance the sheet edgewise, means for dewatering the sheet by suction applied through the support and belt, a rotary calendering and compressing element in contact with the sheet, a shaft supporting the element for rotation, means for rotating the element, eccentric bushings encircling: the shaft, bearings supporting the shaft and bushings for rotation, and means for rotating the shaft and bushings.

2. An apparatus for the manufacture of fibrous cement sheets, which comprises an endless continuously movable hollow support having a horizontal upper stretch, an endless water-pervious belt encircling the support and lying in contact with the top of the support in said stretch, means for depositing aqueous fibrous cement material upon the portion of the belt in contact with the support, means for forming the deposited material into a sheet, means for moving the support and belt to advance the sheet edgewise, means for dewatering the sheet by suction applied through the support and belt, a rotary calendering and compressing element in contact with the sheet, a shaft supporting the element for rotation, eccentric bushings encircling the shaft, bearings supporting the shaft and bushings for rotation, means for rotating the shaft and bushings, and driving connections between the shaft and element.

3. An apparatus for the manufacture of fibrous cement sheets, which comprises an endless continuously movable hollow support having a horizontal upper stretch, an endless water-pervious belt encircling the support and lying in contact with the top of the support in said stretch, means for depositing aqueous fibrous cement material upon the portion of the belt in contact with the support, means for forming the deposited material into a sheet, means for moving the support and belt to advance the sheet in its plane, means for dewatering the sheet by suction applied through the sheet and belt, a rotary element for calendering and compressing the sheet, a shaft, on which the element is mounted for rotation, eccentric bushings encircling the shaft, bearings supporting the shaft and bushings for rotation, means rotating the element relative to the shaft with a surface speed greater than that of the sheet, and means independent of the elementrotating means for rotating the shaft and bushings.

4. An apparatus for the manufacture of fibrous cement sheets, which comprises an endless continuously movable hollow support having a horizontal upper stretch, an endless water-pervious belt encircling the support and lying in contact with the top of the support in said stretch, means for depositing aqueous fibrous cement material upon the portion of the belt in contact with the support, means for forming the deposited material into a sheet, means for moving the support and belt to advance the sheet in its plane, means for dewatering the sheet by suction applied through the sheet and belt, a rotary element for calendering and compressing the sheet, a shaft, on which the element is mounted for rotation, eccentric bushings encircling the shaft, bearings supporting the shaft and bushings for rotation, means rotating the element relative to the shaft with a surface speed greater than that of the sheet, and means rotating the shaft and bushings at a higher rotational rate than the rate of rotation of the element.

5. An apparatus for the manufacture of fibrous cement sheets, which comprises an endless continuously movable hollow support having a horizontal upper stretch, an endless water-pervious belt encircling the support and lying in contact with the top of the support in said stretch, means for depositing aqueous fibrous cement material upon the portion of the belt in contact with the support, means for forming the deposited material into a sheet, means for moving the support and belt to advance the sheet in its plane, means for dewatering the sheet by suction applied through the sheet and belt, a rotary element for calendering and compressing the sheet, a shaft, on which the element is mounted for rotation, eccentric bushings encircling the shaft, bearings supporting the shaft and bushings for rotation, means for rotating the shaft and bushings, and means driven by the shaft and driving the element at a lower rotational speed than the shaft and at a higher surface speed than the sheet.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS McGrath June 14, 1904 Harrison et a1. Ian. 5, 1926 Brookby Mar. 18, 1930 Dom et a1 June 18, 1935 Dorn et a1; Aug. 13, 1935 Schroder et a1 May 26, 1936 Salvaneschi Sept. 29, 1942 10 8 Brbwn May 8, 1945 Bernard et a1 Apr. 11, 1950 FOREIGN PATENTS Italy Sept. 18, 1939 Italy Dec. 4, 1939 Italy Apr. 11, 1940 Italy Dec. 10, 1940 Great Britain Sept. 1, 1921

Claims

1. AN APPARATUS FOR THE MANUFACTURE OF FIBROUS CEMENT SHEETS, WHICH COMPRISES AN ENDLESS CONTINOUSLY MOVABLE HOLLOW SUPPORT HAVING A HORIZONTAL UPPER STRETCH, AN ENDLESS WATER-PREVIOUS BELT ENCIRCLING THE SUPPORT AND LYING IN CONTACT WITH THE TOP OF THE SUPPORT IN SAID STRETCH, MEANS FOR DEPOSITING AQUEOUS FIBROUS CEMENT MATERIAL UPON THE PORTION OF THE BELT IN CONTACT WITH THE SUPPORT, MEANS FOR FORMING THE DEPOSITED MATERIAL INTO A SHEET, MEANS FOR MOVING THE SUPPORT AND BELT TO ADVANCE THE SHEET EDGEWISE, MEANS FOR DEWATERING THE SHEET BY SUCTION APPLIED THROUGH THE SUPPORT AND BELT, A ROTARY CALENDER-