US3616057A

US3616057A - Pressure-applying device

Info

Publication number: US3616057A
Application number: US805906A
Authority: US
Inventors: Carrol C Sachs
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-03-10
Filing date: 1969-03-10
Publication date: 1971-10-26
Anticipated expiration: 1988-10-26

Abstract

This device disclosed includes an airtight container of flexible material having a valved conduit communicating therewith. Another conduit is connected to the valve and to a source of vacuum. The valve has an inlet from ambient atmosphere. Independent control means are included in the valve for selectively interconnecting the conduits and the inlet.

Description

United States Patent [72] Inventor CarrolC.Sachs [56] References Cited 9938 Cybourn Ave., Sunland, Calif. 91040 UNITED STATES PATENTS [21] P 1,595,487 8/1926 Minton 156/381 [22] Flled Mar. 10,1969 2 3 M 156 580 45 Patented on. 26 1971 983,553 1 4 3,405,019 10/1968 Selletal. 156/382 Primary Examiner- Leland A. Sebastian AtlrneyRoger A. Marrs [54] si fs g s P g DEvIcE ABSTRACT: This device disclosed includes an airtight conalms rawmg tainer of flexible material having a valved conduit commu- [52] US. Cl 156/382, nicating therewith. Another conduit is connected to the valve 156/287 and to a source of vacuum. The valve has an inlet from am- [51] Int. Cl B32b 31/20 bient atmosphere. Independent control means are included in [50] Field of Search 156/293, the valve for selectively interconnecting the conduits and the 287,382,499,580,583 inlet.

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PRESSURE-APPLYING DEVICE One use for which the valve of this invention is especially adapted is in vacuum systems employed for pressure-forming laminated plastic parts. To produce such parts, a bag forming and skin packing process may be followed. By that method, layers of resin-impregnated glass cloth or the like are layed up on a die having a configuration conforming to that desired for a completed part. The die and laminations then are inserted into an airtight flexible container, generally a bag of polyvinyl alcohol material, which is sealed and evacuated in order to apply atmospheric pressure to the part. In some instances the bag is located in an autoclave for achieving greater pressures, and normally it is subjected to heat for curing the resin of the part. The sealant for the open end of the bag is usually zinc chromate which is applied along mating marginal surfaces of the end of the bag.

A length of tubing is inserted between a portion of the mating marginal surfaces into the bag and connected to a source of vacuum for drawing air from within the bag. A simple plug valve has been included in the vacuum line to either connect or disconnect the interior of the bag and the source of vacuum. When the bag initially is subjected to a vacuum, the sheet material of the bag invariably forms wrinkles, including wrinkles where the bag contacts the laminations to be cured. Such wrinkles are unacceptable, at least in many areas of a typical part, because the wrinkles mark the part as the pressure is applied and the cure is effected resulting in a lamination not strictly corresponding to the die. This necessitates the additional step of removing wrinkles in the bag material from critical areas of the part before the part is cured.

In the past, it has been customary to break the sea] at the end of the bag by separating the marginal edges so that the vacuum is released and the wrinkles may be worked away from the part. A partial vacuum is necessary as the bag is straightened, however, so that the wrinkles can be effectively moved yet no new wrinkles will take their places. Therefore, the valve in the vacuum line is left open and the seal is broken at only a limited portion ofthe end of the bag. This enables the vacuum pump to maintain the pressure within the bag at a value below atmospheric. After the wrinkles have been removed, the open end of the bag again is sealed, full vacuum is pulled and the remainder of the forming process may take place.

This procedure obviously is disadvantageous because of the time involved in first separating the marginal portions of the bag to break the seal and then resealing after the wrinkles have been removed. Care must be exerted to provide only a limited aperture into the bag when the opening is made so that a partial vacuum can be maintained by continued operation of the vacuum pump. In addition, the open connection between the atmosphere and the vacuum line permits contamination of the vacuum source as air continuously is drawn into the bag and then out through the vacuum line. Also, of course, the vacuum source must perform the work of pumping air all during the time the wrinkles are being removed from the bag.

One of the most troublesome conditions with conventional bag forming is encountered after the assembly has been heated. Frequently, the valves in the vacuum line stick after being subject to heat, becoming very difficult to operate and requiring early replacement. Only a simple "on" or "off" type control is possible with the valves customarily employed.

According to the provisions of this invention, a valve may be included in the vacuum line which provides a close control of the amount of vacuum in the bag, is quick and easy to operate, and is not adversely effected by elevated temperatures. One embodiment of this valve includes a body having three ports, one of which may be connected to either of the other two as controlled by two spring pressed poppets. A resilient seal of silicone rubber is included in each poppet, and cam lever actuators operate each poppet independently. This valve is used in bag forming to maintain the proper pressure within the bag at all times.

Aside from providing an excellent closure seal, the valve is not subject to stoppage or faulty operation which normally occurs when conventional valves are employed, since the valve of the present invention is not susceptible to contamination. Because of this feature, the valve may be readily employed in fluid dispensing applications such as soda or water valves in the food industry where sanitation is of paramount importance or for certain types of exotic fluid control in the atomic energy processes and systems. In instances requiring precisely metered mixing of different fluids, the present valve has been of particular advantage such that the spring biased poppets are independently controlled by the cam lever actuators that may be manually operated or may be incorporated into an automatic powered or electromechanical operating system. Such a system is susceptible to be programmed to effect the desired metered mixing of the fluids.

Therefore, it is a primary object of the present invention to provide a novel valve apparatus operable to precisely control metered fluids throughout a process cycle that is resistant to high temperatures.

Another object of the present invention is to provide a novel fluid control valve having improved control characteristics including effective closure and freedom from contamination.

An additional object of the present invention is to provide an improved arrangement for vacuum bag forming whereby the vacuum created may be precisely bled from the interior of the bag by a manually operated actuator.

Yet another object of the present invention is to provide a novel valve which gives ease of operation and durability of service, particularly in fluid control and dispensing applications requiring sanitary handling of the fluid.

A further object of this invention is to provide an improved arrangement for controllably removing wrinkles in a bag forming operation without necessitating the separation of the edge marginal regions of adjacent bag sides.

Yet another object of this invention is to provide means for selectively controlling the pressure within a sealed container as employed in applications requiring pressure to be applied to a part.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, in which:

FIG. 1 is a sectional view of the fluid control valve of the present invention;

FIG. 2 is a sectional view of the valve shown in FIG. I as in the direction of arrows 2-2 thereof, illustrating the end of the poppet and its sealing seat;

FIG. 3 is a fragmentary side elevational view of the valve arrangement of FIG. 1 showing the bifurcated end portion of the cam lever actuator employed for one of the poppets;

FIG. 4 is a perspective view of the valve apparatus of FIG. 1 employed in conjunction with a bag forming arrangement when a vacuum is drawn initially within the bag;

FIG. 5 is a perspective view, similar to FIG. 4, but with the wrinkles in the bag material removed;

FIG. 6 is a schematic view illustrating the valve of FIG. I in position for drawing air from within the bag to remove material wrinkles; and

FIG. 7 is a schematic view, similar to FIG. 6, but with the valve closed to seal off the interior of the bag.

Referring to FIGS. 1, 2 and 3, a fluid control valve in accordance with the present invention is indicated in the general direction of arrow 11 that preferably is of stainless steel material and is provided with intercommunicating ports 12. 13 and I4, the former two of which are threaded in the embodiment shown. Passageways I5 and 16 provide communication through the valve body interconnecting the ports. Poppet assemblies l8 and 19 are inserted in the ends of the body and carry reciprocative poppets or plungers 20 and ZI, respectively, for controlling the flow of fluid through passageways l5 and 16. The shanks of

poppets

20 and 21 are received within threaded

members

22 and 23, conveniently formed with hexagonal heads located outside of the valve body at its extreme opposite ends while the threaded

portions

26 and 27 of these members are held within complementary threaded end openings in valve body 1 1. Seal 29, preferably of heat resistant material such as silicone rubber and in the form of O-rings, prevent leakage around the exterior of the poppet assemblies. The ends of the body are recessed for receiving these O-rings which will seal effectively even when the threaded

members

22 and 23 are only fingertight within the openings in the ends of the body. This feature greatly enhances and facilitates ready maintenance and repair.

Poppet shanks 31 and 32 extend out through the hexagonal heads of

members

22 and 23 and are sealed to prevent leakage by O-

rings

33 and 34 adjacent shoulders 35 and 36 formed in the threaded members. Preferably again, a high temperature resistant material such as silicone rubber is utilized for the seal. Poppet closure heads 37 and 38 of the poppet assemblies are engaged by expansion springs 39 and 40, the other ends of which bear against washers a1 and 42. A spring force, therefore, forcibly urges the heads of the poppets against annular tapered

valve seats

43 and 44 to close passageways l and 16. The spring force reacting through

washers

41 and 42 also urges the O-

rings

33 and 34 against shanks 31 and 32 of the poppets and the bores of

members

22 and 23 to assure that a seal will be maintained. The poppet closure heads are provided with coaxial recesses 45 and 36 having annular converging tapered sidewalls 47 and 48 defining the recesses. At the base of the sidewalls terminating at the bottom of the recesses, elastomeric wait; 50 and 51 are provided and which are disposed within retainer grooves formed in the closure heads so that the seals are held therein by means of an interference type fit. The poppet heads tapered sidewalls mate with the

tapered seats

43 and 44 so that the terminating ends thereof engage with seals 50 and 51 in an airtight manner when the poppets are urged thereagainst by the springs. Silicone rubber is used for the composition of these seals just as for the O-rings previously mentioned.

Actuation of the poppets is effected by

cam levers

52 and 53 which are pivoted on

pins

54 and 55 to the outer ends of the poppet shanks. These actuating members include bifurcated cam ends 56 and 57 which are rounded on one edge and adapted to engage the ends of

hexagonal head members

22 and 23. The lengths of these cam ends beyond their pivot points 54 and 55 are such that when they are moved to a position of alignment of the poppet shafts, they react against

heads

22 and 23 to move the poppets axially. By this construction, if a lever 53 is pivoted, for example, cam end 57 reacts against head 23 thereby axially moving the puppet in opposition to spring 40 retracting poppet head 21 away from valve seat 48. This opens passageway 16 thereby interconnecting port 13 and port 14.

At the same time if lever 52 is in the position of FIG. 1, where it does not engage or react against the end of hexagonal head 22, the cam lever will exert no force on the poppet so that spring 39 will hold poppet head 37 against valve seat 43 closing passageway 15. Seal 50 assures that there then will be no connection between ports 13 and 12 or

ports

14 and 12.

It can be seen, therefore, that actuation of the poppets is effected independently, and simply by pivoting the actuating members through an arc. The cam type of movement of the poppet permits close control of the poppet, but at the same time is trouble free and easy to operate. All of the seals in the valve are particularly effective in preventing any fluid leakage and, of course, are resistant to elevated temperatures. The construction of the valve is such that the parts will not stick or become difficult to operate regardless of the type of usage to which the valve is applied. Repeated high temperature cycles cause no loss of effectiveness of this valve.

When the valve of this invention is used in a bag forming operation, for example, port 12, which is provided with pipe threads, receives fitting 58 of conventional vacuum line 60 connecting to a suitable remote vacuum source which includes an accumulator 61, and a vacuum pump 62. Port 13 is provided with straight threads and fitting 63 engages the valve body within this port. Silicone rubber O-ring 64 seals at the head of fittings 63, and the body may be recessed as shown to receive this O-ring. Stainless steel flexible tubing 65 is connected to fitting 63 being brazed or welded at numeral 66 to the inner end of this fitting. This type of connection provides a support for the tubing and a more durable arrangement results. Fitting 63 holds tubing 65 throughout the axial length of the fitting, thereby forming an outer tubular support which maintains rigidity adjacent the joint 66 at the end of tubing 65. Because of this, the joint lasts much longer than it would if it were otherwise positioned, such as at the opposite end of the fitting where no such support would be provided.

Tubing 65 provides a conduit extending to a bag 67 of airtight, flexible material such as polyvinyl alcohol, as may be seen in FIGS. 4 and 5. The tubing passes through end 68 of the bag where the edges of upper and

lower sheets

70 and 71 are sealed by zinc chromate. A part 72, located within the bag, is a layup of plastic-impregnated cloth or the like over a die, and is to be pressurized and cured within the bag. Preferably a resin filter trap or debris trap 73 is coupled into tubing 65 that is suitable for collecting resin resulting from the flow, thereby preventing it from reaching the valve where it might cure and immobilize the moving parts of the valve.

With the elements so arranged, the valve is positioned as schematically illustrated in FIG. 6 to close port 14 and open port 12 so that vacuum source 62 evacuates air from within container 67 through line 65 and the valve. Ambient atmospheric pressure forces the bag tightly around part 72. When this is done, wrinkles 74 form in the bag material around the part, as seen in FIG. 4, and these must be removed before the assembly is subjected to heat for curing the part. Instead of breaking the seal at end 68 of the bag, port 12 then is closed disconnecting the interior of the bag from the vacuum source. After this, port 14 is opened momentarily so as to bleed in a limited quantity of air to the interior of the bag, reducing the vacuum. The poppet 21 is easily controlled to allow any desired amount of air to enter the bag so that optimum conditions for moving the wrinkles are obtained. As soon as this condition exists, poppet 21 is closed to the position of FIG. 7 so that the valve maintains the bag interior sealed both from the atmosphere and from the vacuum source and the partial vacuum is maintained. The wrinkles then are removed, following which poppet 20 is opened (repositioning the valve as shown in FIG. 6) to connect the bag with the source of vacuum and the part becomes pressurized in a smooth, wrinkle-free bag.

By this arrangement, it is possible to remove the wrinkles from the part much more quickly than as accomplished by prior practices without wasting or contaminating the vacuum source. It is not necessary to break the seal along the edge of the bag at any time and a close control of the air supply is obtained so that ideal conditions for removal of the wrinkles can be achieved.

It can be seen from the foregoing, therefore, that I have provided an improved valve of serviceable construction, usable at high temperatures without danger of sticking. While by no means limited to such purpose, this valve is especially effective in providing an improved means for controlling the vacuum applied to a bag for pressure-forming plastic laminated parts.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects. and. therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

l. A device for applying pressure to a workpiece comprismg:

an airtight container of flexible material;

a conduit communicating with the interior of said container;

a valve connected to said conduit;

an additional conduit connected to said valve;

a source of vacuum connected to said additional conduit;

said valve having an inlet from ambient atmosphere; and

independently controlled means in said valve for selectively connecting said first mentioned conduit with said last mentioned conduit; and with said inlet to said valve,

said valve includes three ports communicating with said conduits and inlets respectively;

poppet means for selectively controlling the fluid flow through said conduits and said inlet; and

said control means including lever means for moving said poppet means.

2. The invention as defined in claim 1 including valve seat means in each of said conduits;

silicone rubber sealing members for engaging said valve seat means;

spring means for urging said sealing members against said valve seat means; and wherein said lever means moves said poppet means in opposition to said spring means to a location wherein said sealing members are remote from said valve seat means.

3. The invention as defined in claim 1 wherein at least two poppet means are provided for selectively controlling the communication between one of said ports and either of the other of said ports.

4. The invention as defined in claim 1 wherein said container includes upper and lower sheets having mated peripheral edges sealed by zinc chromate.

5. The invention as defined in claim 1 including a filter coupled into said first-mentioned conduit disposed between said valve and said container.

6. The invention as defined in claim 1 wherein said container is hollow so as to receive a die and a workpiece to be formed about the die and wherein said container comprises a pair of deformable flat sheets having their peripheral edges aligned and sealed together.

7. The invention as defined in claim 1 including a debris trap carried in said first mentioned conduit disposed between said valve and said container

Claims

2. The invention as defined in claim 1 including valve seat means in each of said conduits; silicone rubber sealing members for engaging said valve seat means; spring means for urging said sealing members against said valve seat means; and wherein said lever means moves said poppet means in opposition to said spring means to a location wherein said sealing members are remote from said valve seat means.
3. The invention as defined in claim 1 wherein at least two poppet means are provided for selectively controlling the communication between one of said ports and either of the other of said ports.
4. The invention as defined in claim 1 wherein said container includes upper and lower sheets having mated peripheral edges sealed by zinc chromate.
5. The invention as defined in claim 1 including a filter coupled into said first-mentioned conduit disposed between said valve and said container.
6. The invention as defined in claim 1 wherein said container is hollow so as to receive a die and a workpiece to be formed about the die and wherein said container comprises a pair of deformable flat sheets having their peripheral edges aligned and sealed together.
7. The invention as defined in claim 1 including a debris trap carried in said first mentioned conduit disposed between said valve and said container.