US2615200A

US2615200A - Method and apparatus for wrapping articles in stretchable sheet material

Info

Publication number: US2615200A
Application number: US75322A
Authority: US
Inventors: Charles E Cloud
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-02-09
Filing date: 1949-02-09
Publication date: 1952-10-28
Anticipated expiration: 1969-10-28

Description

Oct. 28, 1952 c. E. CLOUD 2,515,200

Y METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIAL l6 Sheets-Sheet 1 Filed Feb. 9, 1949 Oct. 28, 1952 c. E. CLOUD 2,615,200

METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIAL Filed Feb. 9, 1949 16 Sheets-Sheet 2 Oct. 28, 1952 c. E. CLOUD 1 2,615,200

METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIAL Fi led Feb. 9, 1949 1e Sheets-Sheet s Oct. 28, 1952 E CLOUD 2,615,200

C. METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIAL Filed Feb. 9, 1949 16 Sheets-Sheet 4 Oct. 28, 1952 c. E. CLOUD METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIAL Filed Feb. 9, 1949 16 Sheets-Sheet 5 azmzed 67W C. E. CLOUD METHOD AND APPARATUS FOR WRAPPING ARTICLES IN Oct. 28, 1952 STRETCHABLE SHEET MATERIAL l6 Sheets-Sheet 6 Filed Feb. 9, 1949 gill/l Oct. 28, 1952 c. E. CLOUD METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIAL Filed Feb 9, 1949 16 Sheets-Sheet '7 nn/@2251 M 67 W Zama C. E. CLOUD METHOD AND APPARATUS FOR WRAPPING ARTICLES IN Oct. 28, 1952 STRETCHABLE SHEET MATERIAL l6 Sheets-Sheet 8 Filed Feb. 9, 1949 Oct. 28, 1952 c. E. CLOUD 2,615,200

METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIAL Filed Feb. 9, 1949 16 Sheets-Sheet 9 Oct. 28, 1952 c. E. CLOUD METHOD AND APPARATUS FOR WRAPPING ARTICLES IN .STRETCHABLE SHEET MATERIAL l6 Sheets-Sheet 10 Filed Feb. 9, 1949 Oct. 28, 1952 E. CLOUD METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIAL Filed Feb. 9, 1949 16 Sheeis-Sheet l1 E?! n: I

Oct. 28, 1952 METHOD Filed Feb. 9, 1949 c. E. CLOUD 2,615,200 AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE $HEET MATERIAL l6 Sheets-Sheet 12 Oct. 28, 1952 c E CLOUD 2,615,200

METHOD AND APPARATUS. FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIAL Filed Feb. 9, 1949 16 Sheets-Sheet 13 zz -zj I LUG o- PINION :91 (FIGJQ) LUG ON FLOATING PIN- 9 f% PINION :as/ 97 Xw m Oct. 28, 1952 c. E. CLOUD 2,615,200

METHOD AND APPARATUS FOR WRAPPING ARTICLES IN .STRETCHABLE SHEET MATERIAL Filed Feb. 9, 1949 16 Sheets-Sheet l4 CLAMP PLATE HEATER PAD Z, y26' [a CONSTRICTIONS DRAW /4 CYLINDER vAc. PUMP VAC. TANK 81 //0v. l M

2/3 or r 2/0 *fi-zm Z. Q" Z I I A A E I 1 1 23/ n 1 I Q 0 I 1 ++r-. O o l A l w 23.2 1| I l r I 231' I! 1 I U i I II I I I 3 I W Viva/@133 L-Ll Oct. 28, 1952 c. E. CLOUD METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIAL l6 Sheets-Sheet 15 Filed Feb. 9, 1949 4. illilfflh Oct 28, 1952 METHOD AND APPARATUS FOR STRETCHABLE SHE Filed Feb. 9, 1949 iz -ja Patented Oct. 28 1952 METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET 111A- TERIAL Charles E. Cloud, Wilmette, 111., assigner to William S. Cloud, Wilmette, 111.

Application February 9, 1949, Serial No. 75,322

21 Claims.

This invention relates to methods of wrapping articles in stretchable sheet material and to apparatus for practicing such methods.

In practicing some aspects of my invention, it is necessary that the sheet material used be stretchable, or be capable of being rendered stretchable by the application thereto of heat, chemicals or other softening means. In some practices of my invention, the sheet material is also preferably transparent, moisture-proof, impermeable to air and certain other gases, and heat-scalable; that is, capable of having engaging portions fused together when heated. One such sheet material which has all of these characteristics suitable for practicing my invention, and which is commercially available, is a flexible transparent stabilized rubber hydrochloride film. Such material is well-known in the trade under the name of Pliofilm, being manufactured by the Goodyear Tire & Rubber Company of Akron, Ohio, under Patent No. 1,989,632. The stabilization seems to be desirable for lasting qualities of the film, rather than being necessary for this invention.

There are numerous, well-recognized advantages in wrapping articles-in material which con forms to the exact size and shape of the articles, especially where the material is transparent. Several methods have been devised to do this. One, as described in Patent No. 2,312,049, involves suspending a stretchable sheet in horizontal position over a metal frame, manually forcing the article against the sheet to form a pocket therein containing the article, manually twisting the article and the sheet to close and seal the pocket, and severing the excess portion of the sheet by a knife or other cutting means.

A fully automatic apparatus for practicing another method is described in Patent No. 2,403,- 482.

One of the objects of my invention is to provide methods and means for wrapping articles in material which conforms to the exact size and shape of the articles, but which eliminate the hand operations, reduce cost, increase speed and simplify the apparatus.

Other objects and advantages will appear from the following description and from the drawings.

Two general embodiments of the invention, selected for the purposes of illustration, are shown in the accompanying drawings, in which:

Figure 1 is a fragmentary and simplified side elevation of the machine.

Fig. 1A is a somewhat diagrammatic sectional view of a modification of the invention for spot heating of the film.

Fig. 2 is a transverse section approximately on the irregular line 22 of Fig. 1, some parts being omitted for clarity.

Fig. 3 is a detail section showing the mechanism for raising and lowering sleeves 4| and associated parts.

Fig. 3A is a detail section showing alternative apparatus for opening and closing bottom plate 4:1.

Fig. i is a detail section showing the mechanism for raising and lowering holding plate l7.

Fig. 5 is a detail section showing the mechanism for driving sprocket chain 4, which feeds the sheet material.

Fig. 6 is a horizontal sectional view looking downwardly and taken approximately on line 6-45 of Fig. 1, showing the mechanism for driving geared rings til, the parts being moved from the Fig. 1 position.

Figs. 7 to 12 are diagrammatic views illustrating the various changed positions in the operation of wrapping a spherical object.

Fig. 13 is a view showing the upper face of a sleeve type of closing device as a modified form of the invention.

The remaining figures show a preferred modification of the invention as follows:

Fig. 14 is a view of this preferred form of the invention from above.

Fig. 15 is a diagrammatic side representation of the structure of Fig. 14.

Fig. 16 is a side view of the structure shown in Fig. 14, some parts being omitted for clarity.

Fig. 1'7 is a vertical sectional view taken approximately on the line lL-dl of Fig. 16, the lower part of the apparatus being omitted.

Fig. 18 is a fragmentary detail sectional View taken approximately on the line iii-l8 of Fig. 17.

Fig. 19 is a fragmentary longitudinal vertical sectional View taken approximately on the line E@i of Fig. 17.

Fig. 20 is a fragmentary transverse vertical sectional View taken approximately on the line iii-2b of Fig. 16.

Fig. 21 is a view looking down the choke rings removed from the machine, the dotted line showing the position of the strands when one ring has been turned with respect to the other to stretch the bands across the space.

view illustrating a modification of the invention in which the film seals directly against the upper edge of the vacuum sleeve.

Fig. 23 is a horizontal sectional view taken approximately on the line 23-23 of Fig. 19 to show the support of the choke ring.

Fig. 24 is a fragmentary sectional view taken approximately on the line 2424 of Fig. 23.

Fig. 25 is a fragmentary detail view showing the cam control of the vacuum lines for operating the vertically moving parts of the apparatus.

Fig. 26 is a diagrammatic representation of the vacuum system.

Fig. 27 is a diagrammatic representation of the electrical system.

Fig. 28 is a fragmentary vertical sectional View showing an adapter for reducing the effective size of the main vacuum chamber.

Figs. 29 through 36 are diagrammatic vertical sectional views showing the successive stages of the wrappin of one article.

Fig. 37 is a fragmentary sectional view showing a modified form of the invention cutting the material along a smaller line.

Fig. 38 is a diagrammatic view showing the way in which the structure of Fig. 37 save-s material.

Although the law requires a full and exact description of at least one form of the invention, such as that which follows, it is, of course, the purpose of a patent to cover each new inventive concept therein, no matter how it may later be disguised by variations in form or additions of further improvements; and the appended claims are intended to accomplish this purpose by particularly pointin out the parts, improvements or combinations in which the inventive concepts are found.

General operation vIn the forms of the invention shown in the drawings, a web or sheet 6 of stretchable material is drawn from a roll I, to a position over rings or openings ill in plate il. There the sheet is firmly clamped or held. The portions of the sheet immediately over the openings are forced down through them to form pockets into which the articles are deposited. The tops of the pockets are closed, and the pocket portions of the sheet containing the wrapped articles are cut out. The balance of the sheet is then advanced and the process repeated.

Sheet feed (Fig. 1)

A roll I of sheet material 6 rests on rollers 2 and 3. This arrangement permits greater ease and speed in the changing of rolls than does the usual mounting and is preferred in some respects, although it was not conceived by me. Roller 3 is driven intermittently through a sprocket by sprocket chain 4, in timed relation to the movement of heating drum 8 and wringer rolls I 2, the combined movement of which advances sheet material 6. If the sheet material is not stretchable. in its natural condition, it is now exposed to chemicals or heat to so render it. Although methods and apparatus for treating sheet material to render it stretchable are old in the art, I have illustrated one method of heating the sheet material, Which is appropriate for common Pliofilm, indicated above as being suitable for practicing my invention. Other methods of heating are illustrated in Figs. 1A, and 14 to 27, and are disclosed in Patents Nos. 2,312,049 and 2,403,482. In themethod here illustrated, the sheet 6 passes under guide roller '1, around heating drum 8 and under guide roller 9. Heating drum 8 is pref erably driven intermittently by chain 4, and is maintained at the proper temperature by steam or any other convenient means. From the guide roller 9 the sheet is drawn by feed rolls l2 over openings ID in plate or support H. The sheet pauses while portions of the sheet are forced through holes ID to form pockets in which articles are wrapped. After the wrapped articles have been severed from the web, the remainder of the web is drawn on by feed rolls [2, at least one of which is intermittently driven by chain 4. This remainder or scrap may pass from the feed rolls I2 to suitable wind-up means such as revolving core, which may be located outside of the limits of the drawings. The sellers of a particular sheet material will be able to advise the approximate temperature to which it should be heated to be readily stretchable, and the heating should be adjustable so that the exact optimum temperature can be reached by observing the operation. By proper placement of the openings in plate H, and proper advancing of the sheet material, the remainder (scrap) thereof is preferably reduced to as little as is consistent with proper handling and disposal thereof, which may vary with the sheet material being used.

The apparatus for activating sprocket chain 4 and for the timing thereof is best illustrated in Figs. 1 and 5. Main cam shaft 2| which, directly or indirectly, controls all parts of the machine, is driven constantly by sprocket chain 22, which is connected in the usual manner to a motor (not shown). As shown in Fig. 5, a cam 24 is affixed to shaft 2!, which rotates in bearing blocks 23. This cam 24 actuates cam follower or lever 26, pivotally supported by shaft 21. The movement of lever 26, caused by cam 26, controls the movement of link .25, pivoted on shaft 28, and which intermittently drives sprocket chain 4. The intermittent drive is accomplished by means of any suitable overrunning clutch device, typified by roller 29. This mechanism is biased for return movement by tension spring 30, of which one end is attached to the frame and the other to lever 26.

Sheet holding A fresh portion of sheet 6 having been advanced to a position over rings or openings It] in plate I I, mechanism becomes efiective for firm- 1y clamping or holding this portion over the openings while the portions of the sheet immediately over the openings are forced down through them to form pockets and until after the pockets have been filled, closed and cut off. Methods of holding sheet material, and apparatus for so doing, are old in the art. It can be done by either fluid or mechanical pressure. I have shown one form of apparatus for doing this in the drawings, especially Fig. 4.

Slidably mounted on vertical rods or shafts l 6, and held horizontally thereby, is a top or holding plate [1, containing, as best illustrated in Figs. '7 to 12, openings 20 corresponding in size and shape to the openings It in plate ll. Plate I1 is biased downwardly by tension springs [8, of which one end is attached to the frame and the other to cam followers or levers [9, which are adapted to regulate the vertical movement of plate I! by means of links 15. Levers l9 are pivotally mounted on shaft 21 and are uniformly controlled by having one end of each ride on cams 3|, carried by shaft 2|, which cams are so shaped as to allow or assist tension springs i8 to lower plate ll, when the forward motion of sheet E5 has ceased, to clamp the sheet between plate il and plate H and hold it while pockets are formed, filled, closed and cut off, at which time they raise plate l1. Although I prefer to have two sets of cams affixed to opposite ends of shaft ii, for purposes of simplification only one set of these cams, and their related levers, are shown on certain of the drawings.

To avoid the ossibility of rupturing sheet 6, and to secure a firm grip on the edges of the pockets where the stress on the held portion of the sheet will be greatest, I prefer to ttach to the lower edges of the openings 2% in plate ll rings 32 of sponge rubber or other resilient and non-abrasive material. This is best shown in Figs. 7 to 12. It may also be desirable to round off the upper edges of the openings ill in plate i l, to prevent rupturing.

Pocket forming Fresh portions of sheet 6 being held over the openings ill in plate ii, there becomes effective the mechanism for forcing these portions through the openings to form pockets.

Pockets have heretofore usually been formed by fiuid pressure, or by mechanical pressure, the latter in some cases exerted by the articles which are ,to be enclosed in the pockets. Combinations of these methods have been used. I prefer to make the initial forming of the pockets by fluid pressure and thereafter to further enlarge them by a gripped stretch (moving apart two positively held parts of the pocket). This is preferred for a number of reasons, including the following:

First, the use of any one of the methods alone is inefficient in its use of sheet material. It has long been recognized that a vacuum is progressively more effective toward the center or bottom of a pocket created by it, so that the material from which the pocket is formed becomes progressively thinner toward the center. Thus, the use of acuum alone inherently prevents the forming of the largest size pocket which could be made from a given area of material, and the walls of the pocket that is formed will be of widely varying thickness and strength. It has also been recognized that, due in part to friction, stretching by a member exerting mechanical pressure against the center stretches mostly the portions away from the center or bottom of a pocket formed by it, so that it has the same inherent limitations although the thinner portions of pockets formed by it are placed differently. Stretching by the weight of an object to be wrapped has the same effect as stretching by mechanical pressure, and should be considered as merely a form thereof. Obviously, as the two forms of stretching produce opposite results, they somewhat offset one another, but the results are believed to vary. Different surfaces used for the mechanical stretching permit varying slippage with different amounts and distribution of stretching. By following the fluid stretch with a gripped stretch as in the present invention such slippage is avoided. The results are more dependable andgreater stretching of the neck portion of the pocket seems practical. It is to be understood that apparatus for forming pockets by either fluid pressure or mechanical pressure, either alone or in any combination, could be used with some features of the present invention.

The preferred method of pocket forming, as well as some prior methods, has the advantage of preforming the pockets. One broad field in the 6, packaging art includes the packaging of liquids. Liquids cannot be packaged without difficulties unless either a preformed pocket is available or dams are provided. Similar difficulties are encountered in the packaging of loose material or powder, such as cement, tea or bouillon powder, and in the packaging of gases. All of these types can be readily packaged by the apparatus illustrated and described, with a suitable pocketiilling device.

Slidably mounted on vertical rods or shafts l6, and held horizontally thereby, is horizontal casting or beam 36 (Fig. 2). As best seen in Fig. 3, the vertical movement of beam 3-5 is governed by cams 38 attached to shaft 2i and which rock cam followers or levers t'l, pivotally mounted on shaft 27. The end of levers 3T remote from the cams 38 are attached to beam 38-by links ill. Beam 36 is biased upwardly by tension springs 39 (Fig. l) of which one end is attached to the frame and the other to levers Te-l. Cams 38 are so shaped as to allow tension springs as to raise beam 33 approximately as the sheet is gripped between plates 5 l and ll, the cam lowering beam 36 when the mechanical stretching is to be done. Rigidly attached to beam 36 are tubes or sleeves H, the inside diameter of which, as best illustrated in Figs. (-12, corresponds in size and shape to the openings in plates H and F. The tubes 4| may be held by set screws in collars 2 8 preferably cast as parts of beam 36. Tubes ii are so positioned that when beam 36 is fully raised a substantially air-tight contact is made between the tops of tubes M and the bottom edges of the openings in plate ii. To ensure the tightness of this contact, it may be desirable to cement gaskets M to the lower edges of the openings it in plate I I. Also attached to beam 36, by hinges ls, is a bottom plate 3 adapted to be swung up to form an air-tight closure at the bottoms of tubes ll. Here again, to ensure the tightness of the contact, it may be desirable to surface plate with a layer of sponge rubber d8 having an impervious upper face. The term shell may be used to designate the pocketing unit which is illustrated as embodying mainly the tube ll, this term being especially suitable when it is. desired to imply that the bottom is closed during the draw-down of the pocket without specifically mentioning the bottom plate id. If fragile articles or ones which bruise easily are to be dropped into the pockets, it may be desirable to add a second layer of sponge rubber ti'i, which may be of such size and shape that it will fit into the bottoms of the tubes. Tubes M are connected with a vacuum pump (not shown) by vacuum hose 6%) (Fig. 1) through ports 5i (Figs. 2, 7 and 8) which lead through the containers id and sleeves ii. The vacuum pump can operate continuously.

As the sheet 6 is being gripped between plates H and H, levers 3'5, riding on cams 3S, allow tension springs 39 to raise sleeves fill into contact with plate H. The movement of levers 3'! also indirectly operates bottom plate i l attached by hinge 43 to beam 35. The end of bottom plate l t, extending beyond hinges d3, strikes resilient adjustable stops 52, swinging up bottom plate 5 5 into contact with the bottoms of tubes ill. To ensure closure at all points, a separate bottom plate may be provided for each sleeve ill, each actuated by a separate stop 52.

An alternate apparatus for operating bottom plate M is shown in Fig. 3A. There a tension spring 53 is attached at one end to the frame and at the other to a rope, the other end of which extends through and is knotted above the end of each bottom plate 44. This will operate in the same manner as will set stops 52. The spring 53 or spring stop 52 ensures a closing pressure on plate 44 in spite of variations in the parts, and adjustments for spring 53 may be provided as shown for stop 52.

At this time the vacuum becomes effective through ports to draw sheet 6 into sleeves 4|, as shown by comparing Figs. 7 and 8. On the inside of sleeves 4|, as shown in Figs. 7-12, are mounted

rings

56 and 57, supporting screens 58. Screens 58 prevent the sheet 6 from being pulled through the rather large ports 5| and thus being ruptured. It will be observed that in each tube 4| the film seals against rings 58 and 51 thus closing off the vacuum chamber formed between screen 58 and tube 4|. This shuts off the vacuum from below ring 51 so that expansion of the pocket by vacuum is automatically terminated in about the position seen in Fig. 8. The vacuum stretch having been completed, cams 38 and levers 31 lower sleeves 4|. This does not break the Vacuum holding the pocket down in sleeves 4| because each pocket is sealed against ring 56 by the vacuum. As shown in Fig. 9, lowering sleeves 4|, in which the pockets are held by vacuum, will cause those portions of sheet 5 being held between plate II and rings 55 to be further stretched. Rings 56 extend inwardly beyond screens 58, to give a snubbing effect which, assisted by the roughness of the screen, prevents the film from slipping and perhaps breaking the vacuum during the mechanical sleeves 4| and beam 36 are lowered, stops 52 cease to hold bottom plates 44 against the bottoms of sleeves 4|; but the bottom plate continues to be held up by the vacuum within the sleeves 4!.

Pocket filling The pocket now being fully formed, the articles are deposited therein. As methods of feeding articles into pockets, and apparatus for so doing, are old in the art, it is deemed unnecessary to de scribe the diagrammatically represented feeder 50, the type of which will vary according to the particular article or type of article to be packaged. The form of the invention shown in the drawings is even adapted to package powders, liquids and gases, if vertically moving, possibly tapered nozzles are used for feeding. When necessary to prevent loss of contents, the necks of the pockets may be constricted in two steps, the first (before filling the pockets) closing the neck about the nozzles, and the second closing the necks completely as the nozzles are withdrawn.

Pocket closing To close with greater speed and efficiency, and to allow the use of one closing mechanism regardless of the size or type of the contents of the pockets, I prefer to use the pocket closing mechanism shown in Figs. 1, 2, and 7-12. Rotatably mounted around the upper portions of sleeves 4|, at the outside thereof, are geared rings 6|, the teeth of which mesh so that all such rings may be driven through one of them. At spaced intervals endless bands or strips 62 of rubber or other suitable material are attached between rings 6| and the edges of the openings It in plate These strips do not have to be of stretchable material, although that permits some simplificastretch. As

tion and is preferred. The twisting of rings 6| forces these strips 62 from a separated, substantially vertical position, as shown in Figs. 2, and 7-9, into an intersecting, substantially horizontal position, as shown in Figs. 6, 10 and 11, closing the pockets surprisingly tightly.

The sealing of the pockets may be effected when the pockets are closed, if sealing is desirable. If the sheet material used is the common, nonstretchable Pliofilm, it must have been previously heated to render it stretchable, and the mere closing of the pockets will seal them, since they will not have been stretched excessively or allowed to stand long enough to lose their tackiness. To heat-seal certain other sheet materials, it may be necessary to use strips 62 of resistance wire or other material which will conduct heat and to heat them by electricity at the moment they effect a closure of the pockets. When using other materials which are not heat-scalable, it may be desirable to hold the closure by glue, cord or tape. Apparatus for this is old in the packaging art.

One apparatus which may be used to twist the rings 6| is best shown in Figs. 1 and 6. Mounted in a position to be tripped by the lowering of lever 31 is switch 66 for valve control unit G1, which admits air to cylinder 68, forcing out rack or geared rod 69, which is meshed with gear H mounted on vertical rod or shaft 12, rotatably mounted on the frame, and having mounted thereon gear 73, which is meshed with one of geared rings 6|. The air cylinder and controls are preferably of the type, commercially available, which forces rod 69 first out and then in, thus returning strips 62 to their substantially vertical positions, as shown in Fig. 12, so that the apparatus is readied for the next articles. This type of apparatus permits control of the amount of twisting which is done, which may be necessary if, for example, strips 62 are of resistance wire or other relatively non-stretchable material.

For strips 62 can be substituted a tube 15 of rubber or other suitable material, which may be secured to the choke rings 6| by cement, clamping rings, or both. The twisting in such case will cause the tube to form an annular sheet over the pocket, further twisting causing this sheet to constrict the aperture therethrough and eventually close it, as seen in Fig. 13, squeezing anything within the aperture.

It is believed that the strength of the vacuum holding the film against the screen 58 can be so selected that the constrictor will pull the film away from the ring 56 and screen 58 enough to break the vacuum. In any event, the strength of the vacuum should be adjustable. This may be accomplished by providing an adjustable relief valve or by providing adjustable means for determining the speed of the vacuum pump, assuming it is of a type in which the pressure varies with speed.

To safeguard against the possibility that the vacuum may not be dependably broken in this way, it is preferred at present to provide automatic means for breaking the vacuum in timed relation to the remaining apparatus. For example, a valve to the vacuum line could be opened automatically by a cam on shaft 2|.

It is to be noted that the closing or constricting apparatus described is admirably adaptable for remote uses such as for holding objects and, in the case of the sleeve form, for use where diaphragm closers are necessary, as in cameras.