US3754751A

US3754751A - Suction device for picking up sheets

Info

Publication number: US3754751A
Application number: US00120215A
Authority: US
Inventors: F Capetti; G Terzuolo
Original assignee: Olivetti SpA
Current assignee: Olivetti SpA
Priority date: 1970-03-13
Filing date: 1971-03-02
Publication date: 1973-08-28
Anticipated expiration: 1990-08-28
Also published as: GB1305682A; FR2084435A5; CA942346A; JPS544285B1; DE2112084A1

Abstract

A suction device used for picking up sheets, for example in a paper printing machine, has a valve which automatically closes, cutting off the suction device from a suction manifold, when the mouth of the device is not covered by a sheet, thereby preventing unnecessary loss of suction in the manifold, which usually serves a number of suction devices. The valve is closed by the air which flows through the device when its mouth is uncovered.

Description

United States Patent Capetti et a1.

1 Aug. 28. 1973 SUCTION DEVICE FOR PICKING UP 3.222.059 12/1965 Soulhcutt 1 :s

SHEETS 2.986.392 5/1961 Biittner v r r 1 271/26 715,905 12/1902 Tuck et al 271/26 [75] entors: Fe p G ancar o 1,580,671 4/1926 Nichols 271/27 Terzuolo, both of Turin, Italy [73] Assignee: lng. C. Olivetti & C. S.p.A., Turin, Primary E i r Ev n C. Blunk Italy Assistant Examiner-Bruce H. Stoner, Jr. 22 Filed: Mar. 2 1971 Attorney-Birch, Swindler, MCKl6 & Beckett [21] Appl. No.: 120,215

[57] ABSTRACT 30 A 1' t' D 1 3 g Ion Pnonty am A suction device used for picking up sheets, for exam- Mar. O tay 67858 A/70 p p p p g machine'hasavalve which auto matically closes, cutting off the suction device from a 2% 5" 271/26 sg#3 2 suction manifold. when the mouth of the device is not f i 27 28 covered by a sheet, thereby preventing unnecessary 1 0 11 loss of suction in the manifold, which usually serves a l l number of suction devices. The valve is closed by the air which flows through the device when its mouth is [56] References C ted uncovered UNITED STATES PATENTS 1,222,535 4/1917 Crum 271/26 3 Claims, 4 Drawing Figures s I J :1 v 13 12a gj/ 12a- :1 T

Patented Aug. 28, 1973 3,754,751

2 Sheets-Sheet 1 FIG- 1 BY 3M), mm, m $816M;

ATTORNEY Patented Aug. 28, 1973 3,754,751

2 Sheets-Sheet 13 Q LL.

SUCTION DEVICE FOR PICKING UP SHEETS This invention relates to suction devices for picking up sheets.

The use of suction devices for picking up and transporting sheets, especially sheets of paper in printing machines, is already well known.

Such devices comprise an elongated tubular member, preferably cylindrical, terminating at one end in an open mouth through which the interior of the tubular member communicates with the outside.

The mouth of the suction device can be fixed to the tubular member or mounted for movement relative thereto through the interposition of elastic means. The interior of the tubular member is, in use of the device, connected at its end remote from the mouth to a source of suction such as a suction pipe or manifold.

The tubular member is supported and controlled in such a way that the mouth can be brought up to a sheet to be lifted by suction so as to lift the sheet and, if desired, transport it elswhere.

During these operations suction is started up a little before the approach of the mouth of the suction device to the sheet, and it stops when the suction device reaches the place where the sheet is to be deposited. This is achieved by controlling, by means of appropriate valves, the communication between the interior of the tubular member of the suction device and the source of suction on the machine in which the device is mounted.

In the lifting and transporting of sheets, a number of suction devices arenearly always used simultaneously.

Thus, for example, in automatic sheet feeders for printing machines a number of suction devices are ar- -ranged in a row and attached to a common support which is moved in such a way as to cause the row of suction devices to approach the plane in which a sheet is supported to lift the marginal frontal portion of the sheet. I

The arrangement described above functions correctly, without the need for special equipment, in the case where the sheets to be lifted and transported have a maximum format such as to bring into use, simultaneously, all the suction devices: only in this case is it in practice possible to apply equal suction to all the suction devices. When, on the other hand, it is desired to lift a sheet having a format which is less than this maximum format, or when, for reasons imposed by printing requirements, a sheet has to be moved from its normal position in relation to the suction devices, it inevitably happens that at least one of the suction devices is not covered by the sheet when the latter is picked up, so

that this device continues to suck up air. This air passes into the suction manifold to which all the suction devices are connected, causing unevenness in the suction forces applied to the sheet by the different suction devices which have been brought up to the sheet.

With the object of avoiding this disadvantage in earlier known arrangements, each suction device was provided with a hand-operated valve, usually a simple tap placed so as to be able to cut off and reinstate, as desired, communication between the interior of the tubular member of the suction device and a suction manifold. By selectively operating the taps it was possible to arrange that only those suction devices which were .intended to come into contact with a sheet to be lifted were operative, the others being cut oft from the suction source.

Such an arrangement does not, however, meet the requirements imposed by the use of modern advanced printing machines, which are very fast-acting. The operation of selected taps as aforesaid requires manual skill on the part of an experienced operator, and is necessarily time-consuming, a disadvantage which is often aggravated by the fact that the particular portion of the automatic sheet feeder on which the control taps are located happens to be in a position accessible only with difficulty and/or is such as to require movement of other portions of the associated machine to give access to the taps.

An object of this invention is to avoid these disadvantages and to provide an arrangement which automatically isolates from the suction source the or each suction device which is not juxtaposed to a sheet to be lifted.

According to the invention there is provided a suction device for picking up sheets comprising an elongated tubular member terminating at one end in an open mouth and connectible to a suction source characterised in that the device includes a valve which is normally open and which, in use of the device, controls communication between the mouth of the tubular member and the suction source, the valve being so arranged that it is closed by the action of air passing through the tubular member from the mouth when the latter is uncovered, and is open when the mouth is covered by a part of a sheet.

in one practical embodiment of the invention, the said valve comprises an annular seat in the interior of the tubular member and a spherical closure member in the form of a ball housed in the said interior of the tubular member between the mouth-and the said seat, the said ball being normally spaced from and biased away from said seat, and said ball having a diameter which is less than the internal diameter of the tubular member and greater than that of the seat, so as to leave a radial clearance between the ball and-the internal surface of the said tubular member.

Preferably the weight of the ball and the magnitude of the said radial clearance are such that, when the mouth is uncovered, the ball is moved, as a result of the thrust thereon due to the fall of pressure occuring between the ball and the seat, until the ball rests on and closes the seat, said movement occuring in a period of time which is longer than the time interval, if any, between the commencement of suction and the arrival of the device at a sheet pick-up position, the volume of the interior of the tubular member between the said radial clearance and the mouth being so chosen that the force acting on the said ball as a result of the said fall of pressure when said mouth is covered becomes less than the returning force opposing movement of the ball towards the said seat within a period of time shorter than that necessary for the ball to reach the seat.

The device preferably includes a spring for resiliently opposing movement of the ball towards the seat, and also a stop so positioned within the tubular member as to prevent the ball from moving away from the seat beyond a predetermined limit, when the device is inoperative.

The strength of suction to be applied by the device depends upon the character of the sheets which are to be lifted. In order to achieve in every case optimum performance of the suction device, means are preferably provided for adjusting the load of the spring acting upon the ball.

Further characteristic features and advantages of the invention will be apparent from the following description, given by way of example, with reference to the attached drawings, in which:

FIG. 1 is a longitudinal section of a suction device according to one embodiment of the invention, in a state of rest;

FIG. 2 is a longitudinal section showing the device of FIG. I in one of its possible operational states;

FIG. 3 is a partial longitudinal section, showing the said device in another operational state, and

FIG. 4 is a front elevation, partly in section, of apparatus for the lifting and transport of sheets, of the type employed as automatic sheet feeders in printing machines, having a number of suction devices according to the invention.

The suction device illustrated in the drawings comprises a tubular member 1 having an interior 2 one end of which is provided with an internal flange 3 having a central aperture 4, the edge of which acts as an annular valve seat. The other end of the tubular member 1 carries a mouth 5, having a screw connection to the member 1. The mouth 5 has an axial through bore 6 and constitutes the part which adheres to a sheet during the lifting of the latter in operation of the suction device.

The end of the tubular member 1 opposite the mouth 5 is inserted for a certain distance into a through bore 7 in a clamp body 8 fixed to a tubular support 9. The interior 10 of the support 9 constitutes a suction manifold and is connected by means of a flexible pipe (not illustrated), to a suction pump (also not illustrated).

The tubular support 9 passes through a hole in the body 8, the axis of this hole being perpendicular to that of the bore 7. Clamping of the body 8 to the tubular support 9 is made possible by a gap 11 which is spanned by a clamping screw 12. The screw 12 has a cylindrical terminal appendage 12a which projects into the interior 2 of the tubular member 1 through a radial vent in the side wall of the said member.

In that portion of the interior 2 of the member 1 between the appendage 12a of the screw 12 and the flange 3 there is housed a valve ball 13 the diameter of which is less than the diameter of the interior 2, but greater than the diameter of the aperture 4. This ball 13 is urged (see FIG. 1) against the appendage 12a by the action of a small helical spring 14 one end of which bears against the ball 13 and the other end of which bears against a screw-threaded plug 15 screwed into a threaded end section of the bore 7. This threaded end section is opposite that end of the said bore 7 into which the member 1 is inserted. By adjusting the position of the screw plug 15 in the inside of the vent 7, it is possible to adjust the tension of the spring 14 and thereby the biasing force with which the spring 14 presses the ball 13 against the appendage 12a of the screw 12, the said appendage 12a acting as a stop for the ball 13.

The intermediate portion of the bore 7, communicating with the interior 2 of the member 1 through the aperture 4, is connected with the interior 10 of the tubular support 9 via aligned

radial holes

16 and 17 in the body 8 and the support 9 respectively.

The suction device operates as follows. Shortly before the mouth 5 of the device is brought close to a flat surface upon which a sheet to be lifted rests, suction is applied to the interior 10 of the tubular support 9 by the opening of a valve (not shown) which controls the connection between the cavity 10 and a suction source. As a consequence of this air is drawn through the mouth 5 and flows through the tubular member 1 to the tubular support 9. The strength of this air flow is dependent upon the strength of the suction applied to the part of the device connected to the interior 10 of the tubular support 9. The application of suction may be so timed as to commence after the mouth 5 has reached the flat sheet supporting surface.

In the case where the mouth 5 is not covered by a sheet to be lifted a pressure drop occurs between the ball 13 and the aperture 4 as a consequence of the annular radial clearance 18 which exists between the periphery of the ball 13 an the internal surface of the tubular member 1. The ball 13 is subjected as a result of this pressure drop to a force which tends to move it towards the aperture 4, against the force exerted by the spring 14 and, where the tubular member 1 is vertical,

as illustrated, against the action of the weight of the ball 13 itself. The weight of the ball 13, the tension of the spring 14 and the size of the clearance 18 are selected so that the ball 13 is lifted from the appendage 12a, and approaches the flange 3 to close the aperture 4.

On the other hand, in the case where, upon lowering of the tubular support 9 the mouth 5 of the device is brought close to part of a sheet 21 placed upon a flat support surface 20 (FIG. 4), then communication between the interior 2 of the tubular member 1 and the outside is cut off, and pressures above and below the ball 13 are balanced before the ball 13 is able to close the aperture 4. Provided the time interval, if any, between the application of suction to the device and the movement of the mouth 5 into juxtaposition with the support surface 20 is less than the time taken for the ball 13 to move from the appendage 12a to the flange 3, then the greatest movement which can occur is an upward movement of the ball 13, that is, a movement in the direction of the flange 3 but insufficient to close the aperture 4, as illustrated by dashed lines in FIG. 3; such movement is immediately followed by the return of the ball 13, by the spring 14, to its initial position, in which it rests against the appendage 12a of the screw 12 (FIG. 1). In other words, the volume of the interior 2 of the tubular member 1 is such that, when the mouth 5 is covered by part of a sheet 21, the upward force on the ball 13 due to the initial pressure drop across the ball is reduced to a value less than the returning force on the ball (due to its own weight and the force of the spring 14) in a period of time less than that necessary for the ball to reach the seat 4, so that the suction is not cut off from the device when the mouth 5 is covered.

FIG. 4 illustrates part of an apparatus employing suction devices according to the invention for the lifting and transport of sheets. A number of suction devices are arranged at regular intervals in a row on a common tubular support 9 and form part of an automatic sheet feeder in a printing machine.

In FIG. 4 the tubular support 9 is shown in its lowered position, in which the mouths 5 of the feeding devices are in proximity to the flat surface 20 upon which a sheet 21 to be lifted is supported. In this example the sheet 21 has a breadth which is less than the maximum width of sheet liftable by the devices. Consequently only the two central feeding devices, numbered 22 and 23 respectively, make contact with the sheet 21. The interiors of these devices will remain in communication with the interior of the tubular support 9, which acts as a suction manifold, each

device

22, 23 being in the state illustrated in FIG. 1.

On the other hand, the ball valves of the outer suction devices, numbered 24 and 25 respectively in FIG. 4, are closed shortly after the application of suction, as described above, so that each

device

24, 25 is in the state shown in FIG. 2, and is cut off from the suction manifold (that is, the tubular support 9), obviating the substantial loss of suction which would otherwise occur in the interior 10 of the tubular support 9 and in the

operative suction devices

22 and 23.

The invention is obviously useful even in cases where the suction devices are used separately, in that automatic cut-off of the suction applied to the suction device occu'rs when the mouth of the device is not in close proximity to a sheet which is to be lifted.

It will be appreciated thatdetails of practical embodiments of the invention may be widely varied from what has been specifically described and illustrated purely by way of example, without nevertheless departing from the scope of this invention.

Thus, for example, the seat for the valve ball 13 could be provided within the interior 2 of the tubular member 1, close to the respective mouth 5. In this case the ball 13 and its respective stop 12a would also be situated only a short distance from the mouth 5, as illustrated in broken outline in FIG. 1. The spring 14 would have to be appropriately extended, or else rested against a support different from the plug 15.

The mouth 5 could,-moreover, be of a different shape from that illustrated, and could be made of some material other than metal, for example, rubber or synthetic resin.

What is claimed is: I

-l. A suction device for picking up sheets of papers and the like individually from the top of a pile of sheets for feeding to a copying machine or the like comprisg suction manifold movable through a path toward and away from the sheet to be picked up,

means creating a suction on said suction manifold commencing at a predetermined point in the said path of said manifold toward the sheet to be picked up, and v a plurality of spaced tubular suctionmembers carried by said suction manifold, each of said suction members comprising: I g a suction mouth at the extremityof one end of said suction member and in alignment with the other said suction mouths so that the said suction mouths together contact the sheet to be picked passage means connecting the other end of said suction member to said suction manifold.

w an annular seat in the interior of said suction memher,

a movable ball in the interior of said suction member, said ball being positioned between said mouth and said annular seat and having a diameter greater than the diameter of said annular seat and less than the interior diameter of said suction member, said ball being movable between a first position spaced at first distance from said annular seat, a second position spaced a lesser distance from said annular seat, and a third position wherein said ball engages and closes said annular seat; the distance between said first position and said second position being equal to the distance said ball travels under the influence of the suction created in said suction manifold between the moment that suction commences in said suction manifold as said suction manifold moves toward the sheet to be picked up and the moment the sheet to be picked up would normally be contacted by said mouth, and the distance between said second position and said third position is a predetermined very small distance, whereby upon the application-of suction to said suction member as said suction manifold moves toward said sheet to be picked up said ball begins to move. from said first position toward said second position under the influence of said suction, and said ball arrives at said second position at the moment said suction mouth contacts said sheet to be picked up, but if said suction does not contact a sheet to be picked up, said ball continues through said second position to said third position, thus immediately closing said annular seat, and halt ing the communication of suction to said suction member, and

a ball stop extending into the interior of said suction member at a point between said ball and said mouth and engagable with said ball to define said first position.

2. The suction device of claim] further comprising spring means biasing said ball toward said first position and opposing the movement of said ball toward said and third positions.

3. The suction device of claim 2 further comprising.

adjustable means acting on said spring means to allow adjustment of the force applied by said spring means.

Claims

1. A suction device for picking up sheets of papers and the like individually from the top of a pile of sheets for feeding to a copying machine or the like comprising: a suction manifold movable through a path toward and away from the sheet to be picked up, means creating a suction on said suction manifold commencing at a predetermined point in the said path of said manifold toward the sheet to be picked up, and a plurality of spaced tubular suction members carried by said suction manifold, each of said suction members comprising: a suction mouth at the extremity of one end of said suction member and in alignment with the other said suction mouths so that the said suction mouths together contact the sheet to be picked up, passage means connecting the other end of said suction member to said suction manifold, an annular seat in the interior of said suction member, a movable ball in the interior of said suction member, said ball being positioned between said mouth and said annular seat and having a diameter greater than the diameter of said annular seat and less than the interior diameter of said suction member, said ball being movable between a first position spaced a first distance from said annular seat, a second position spaced a lesser distance from said annular seat, and a third position wherein said ball engages and closes said annular seat; the distance between said first position and said second position being equal to the distance said ball travels under the influence of the suction created in said suction manifold between the moment that suction commences in said suction manifold as said suction manifold moves toward the sheet to be picked up and the moment the sheet to be picked up would normally be contacted by said mouth, and the distance between said second position and said third position is a predetermined very small distance, whereby upon the application of suction to said suction member as said suction manifold moves toward said sheet to be picked up said ball begins to move from said first position toward said second position under the influence of said suction, and said ball arrives at said second position at the moment said suction mouth contacts said sheet to be picked up, but if said suction does not contact a sheet to be picked up, said ball continues through said second position to said third position, thus immediately closing said annular seat, and halting the communication of suction to said suction member, and a ball stop extending into the interior of said suction member at a point between said ball and said mouth and engagable with said ball to define said first position.

2. The suction device of claim 1 further comprising spring means biasing said ball toward said first position and opposing the movement of said ball toward said and third positions.

3. The suction device of claim 2 further comprising adjustable means acting on said spring means to allow adjustment of the force applied by said spring means.