Inflatable Form Breaker For Molded Construction

Abstract

An inflatable device for removing the forms from molded concrete or the like construction including a soft, inflatable bladder having two flat, opposite sides which are distendable. An elongated handle is provided from one edge of the bladder for manipulating the bag, and a pressurizing conduit communicates with the interior of the bladder for inflating and deflating it. The sides of the bladder may be covered with flexible sheet material for protecting the bladder against punctures during usage. The conduit is connected to a pressurizing source and a control is provided for inflating and deflating the bladder. After the construction has hardened a wedge or spacer device, in cooperation with the inflatable bladder, may be inserted between the form and the surface of the construction whereby the spacer and bladder are progressively stepped across or down the surface of the molded construction.

Description

This invention is directed to an inflatable device, which may be used in conjunction with a spacer, for separating a planar form from a molded structure. It is more specifically directed to a form breaker having a generally flat, inflatable bladder having soft sides which can be rapidly inflated and deflated at the interface of the concrete and the form to strip the forms from the concrete.

In the past, it has been common practice where possible to use a crane, mechanical wedge, crowbar or other types of wedging devices to force the forms away from the surface of newly formed concrete or other cementitious castable type construction materials, generally causing damage to the green concrete. Because of the characteristic of the concrete to adhere tenaciously to the form, particularly to decorative surfaced concrete, the stripping of the form from the concrete at times has proved to be a very difficult task. This is especially true where a wall or surface of large magnitude is formed and the arrangement necessitates the use of a large single, built-up form or a plurality of large, individual, pre-assembled forms for forming the structure.

In several pneumatic devices that have been utilized for stripping very small area forms from concrete construction, air is introduced directly between the form and the surface of the concrete in order to force the form away from the surface. For example, U.S. Pat. No. 2,850,785, issued Sept. 8, 1958 to J. F. Rushing, describes the use of dome-shaped molding forms (pans or steel dome forms) to form "waffle type" walls and ceilings. These pans include an air hole through which compressed air may be blown to loosen these pans. These pans are small and once slightly loosened, may be removed. This type of operation is satisfactory where the forms are used in casting the underportion of a ceiling-floor-type structure where the small forms are usually convex and the air permits the form to be uniformly moved at least a short distance downwardly from the concrete to release the form itself. This type of a process is impractical where the form defines a relatively large flat surface of either a ceiling or wall type object. If air is introduced directly between the form and surface of the concrete in this type of construction, the air will rapidly move across only a portion of the surface to the edge where it will escape.

To counter this type of problem, a flat, non-inflatable, disc-type object has been suggested, which is cast directly with the concrete and held against the form during the pouring process, U.S. Pat. No. 3,151,374, issued Oct. 6, 1964 to M. E. Kersten. A stem passes directly through the form to the outside where, upon the curing of the concrete, a pneumatic source is connected to the stem which expands the disc a short distance to break the form, at least in that particular small area, away from the concrete surface. Because of the necessary small size of the disc and the fact that it cannot be moved across the surface, either a large number of the discs must be incorporated in the form or this device can only be used in very small castable structures, such as in the fabrication of cinder blocks or concrete blocks. Further, these leave an impression in the concrete surface.

Inflatable disc-like bladders have been placed in the mold with the concrete poured on the bladders; see U.S. Pat. No. 2,480,477, issued Aug. 30, 1949, to F. H. Jones and U.S. Pat. No. 3,418,767, issued Dec. 31, 1968 to F. Seeger. The impression of the bladder is left in the concrete, and such bladders are useful for only small, pan-like molds.

In the construction of large, single wall-type structures such as reservoirs, tanks and buildings, it is absolutely necessary that an entire section be poured at one time to form a monolithic structure of uniform consistency and color. In this type of construction, literally thousands of the disc-like inflatable devices would have to be installed in the forms which would be impractical, both from a cost standpoint as well as a time consuming operation of individually inflating each unit in series or simultaneously, and their image might not be desirable in the surface of the concrete.

Some mechanical tools are available for removing forms from concrete structures, and these generally require a longer curing time for concrete since they tend to break or mar green concrete. A stripping tool is shown in U.S. Pat. No. 3,316,607, issued May 2, 1967 to S. J. Kroll, which utilizes a concrete contacting cap. This cap extends through the form and concrete is cast against it. The cap leaves an impression on the concrete surface, and unless the concrete sets hard, will leave an indent when the form is stripped. Since it has only a small bearing surface, many of the tools must be used for each form section.

Large concrete tank casting forms with removal apparatus is shown in U.S. Pat. No. 3,539,146 issued Nov. 10, 1970 to W. L. Smith. The stripping device includes pistons for moving inner and outer forms away from each other to expose the cast tanks. This type of device is limited as to size and shape.

The present invention, therefore, is directed to a very simple and economical device requiring only a single unit for stripping forms from the cast cementitious structure.

Another object of the present invention is to provide a form stripping device which can be easily inflated and deflated and may be used in conjunction with a spacer so that the inflatable device and the spacer may be progressively positioned in alternate fashion across or down the surface of the construction to rapidly strip the form from the surface.

Another object of the present invention is to provide an inflatable form stripping device which includes a manipulative handle so that the unit may be used in stripping the forms from vertical as well as horizontal type construction.

A still further object of the present invention is to provide an inflatable form stripping device which can be used with any type of fluid pressurizing medium which is readily available at the construction site.

A still further object of the present invention is to provide a lightweight, easily portable form breaker which is both economical to manufacture and simple to operate.

Another object of the invention is to provide an inflatable stripping tool which reduces the labor of removing forms from the concrete without damage to the concrete.

The present invention includes an inflatable bladder-type form stripping device in one form, which may be used in conjunction with a spacer element, for progressively stripping forms from cast masonry construction. The bladder is preferably formed in rectangular shape having two planar side members which are joined together around their entire periphery to form a sealed inflatable chamber or bag. An elongated handle, which is attached to a clamping means, is connected by the clamp to one edge of the bladder for the purpose of being able to move the bladder across or down the surface of the construction by means of the elongated handle. In one form, to protect the flexible tube or conduit for pressurizing the bladder, the tube is inserted through the elongated handle and communicates with the interior of the bladder. Thus, the handle protects and armors the tube to prevent pinching or separation while a single elongated member is connected to the bladder for easy control and manipulation of the bladder in the form breaking operation. In another form, the tube is merely extended along the outside of the handle. The conduit can be connected to an air compressor or pump by means of a control device such as a simple thumb controlled opening or three-way control valve. With the valve in one position, or the thumb hole closed, pressure can be applied to the bladder and with the control in the opposite position, or the thumb hole open, the bladder can be deflated. The bladder may be connected directly to the inlet of the air compressor of pump and by a three-way valve rapidly deflated. Thus, a slow inflation and deflation of the bladder is possible or a rapid pulsing of the bladder is possible depending upon the type of form breaking operation which is desired.

The spacer device used with the bladder can be either a separate element, such as an elastomeric wedge, or can be a block with a hole passing therethrough so that the block can be slidably positioned on the elongated handle of the bladder. In either configuration, as the bladder is inserted between the form and concrete surface and inflated, the spacer is moved toward the bladder. This retains the form spaced from the concrete surface permitting the bladder to be deflated and moved forward toward the interface of the form and concrete surface. This cycle may be repeated to expand the bladder and further separate the form. In this alternating, sequentially-stepped process, the bladder and spacer are moved progressively across or down the surface of the cast structure to easily and rapidly remove the form from the surface. When made of elastomeric material, damage to green concrete is minimized.

Other features of this invention will appear in the following description and appended claims, reference being made to the accompanying drawings forming a part of the specification wherein like reference characters designate corresponding parts in the several views.

FIG. 1 is a perspective view of one form of inflatable breaker of the present invention, showing an elongated handle attached to one edge of the bladder;

FIG. 2 is a cross section view of the bladder of FIG. 1 taken along the section lines 2--2; the shape of the bladder in the inflated configuration is shown in the dashed lines;

FIG. 3 is a pictorial sectional view which shows a concrete structure and form partly separated by a spacer with a form breaker of the present device inserted between the form and the surface of the concrete;

FIG. 4 is a sectional view of the structure shown in FIG. 3 with the form breaker inflated to further separate the form from the concrete and the spacer positioned to hold the form in its separated position;

FIG. 5 is a side view of another embodiment of the present invention showing the spacer mounted for slidable movement on the handle of the form breaker;

FIG. 6 is a schematic view of one form of control arrangement for the device of the invention;

FIG. 7 is a front elevational view of a modified form of the invention, using a detachable solid handle; and

FIG. 8 is a side elevational view of the device of FIG. 7.

Turning now more specifically to the drawings, in FIG. 1 an inflatable form breaker, shown generally by numeral 10, has a soft, inflatable bladder 11 and elongated handle 12. The bladder 11 includes two flat, planar sides 13, 14 which are sealed together around their entire periphery to form an imperforate bladder 11. In one form, a sheet of soft elastomeric material is folded and the open edges sealed shut.

A clamping or backing device 15, such as an elongated, U-shaped channel, can be attached to one edge of the bladder 11 by means of fasteners 16, such as bolts, sewing or rivets passing through an enlarged edge of the bladder.

The upper edge of the bladder 11, which is attached to the clamp 15, may be formed as an elongated reinforced section 17 which includes an embedded stiffening member 18 which can be molded integrally with the bladder. The handle 12 is securely attached at right angles to the surface of the clamp device 15. If desired, a flexible sheet of tough material 19, which can be metal such as steel or aluminum or one of the tough (generally reinforced) plastics can be arranged around the outer surface of the bladder 11 to protect it and prevent punctures during usage. This may be a simple sleeve or a sheet folded over the bladder.

A hose or conduit 20 connected to a pressurizing source such as a compressor or hydraulic pump (not shown) passes through the handle 12 and communicates directly with the interior of the bladder 11, FIG. 6. A control device, such as a three-way valve 28, connected in the tube 20 between the pressurizing source or compressor 29 and the bladder 11, permits inflation through line 30 and quick deflation through line 31 connected to the inlet of the compressor. When the bladder 11 is inflated, the sides 13, 14 of the bladder 11 take the expanded position as shown by the dotted lines in FIG. 2. Thus, when inflated, the width of the device 10 is greatly increased over the original width of the bladder 11. Also, nominal pressure may be used to inflate the bladder, i.e., 10-30 psi, so that inexpensive, light weight components may be used.

As shown in FIGS. 3 and 4, a concrete wall 21 has been cast in place by use of a form 22. In using the inflatable form breaker of the present invention, an elastomeric spacer member 23 which may have the configuration of a wedge or the like or a rectangular block may be inserted at the upper edge of the formed structure between the form 22 and front surface of the cast wall 21. With the form partly separated from the concrete, the inflatable form breaker device 10, in the deflated configuration, is inserted as far as possible into the interface between form and concrete surface. The bladder 11 is inflated to its fully expanded configuration as shown in FIG. 4. If desired, the pressurization of the bladder 11 can take place in a slow operation with the pressure allowed to escape to the atmosphere or a reservoir for deflation. If desired, the control device, connected in the tube 20, may be arranged to alternately connect the pressurized outlet of the compressor or pump and the suction inlet by the use of the three-way valve arrangement, as shown in FIG. 6. Thus, it is possible to pulse or rapidly expand and contract the bladder 11 to greatly accelerate the operation of removing the form from the concrete structure.

As the bladder is expanded, as shown in FIG. 4, the wedge or spacer falls by gravity to the point where it is wedged between the form and the concrete surface. As the bladder is deflated, the form is held in the separated position (i.e., the gain due to the inflated bladder) by the spacer so that the form breaker 10 may again be repositioned downwardly and then expanded with the spacer moving further downwardly. Thus, in alternating progressive steps, the breaker and spacer may be moved down across the entire surface of the structure so as to completely separate the form from the concrete surface. By progressively moving in stepwise fashion horizontally across the surface of the construction, the entire form may be worked loose and separated from the concrete surface and allowing the form to be removed.

If desired, the spacer element 26 may include a central bore so that the spacer 26 may be positioned over the handle 12 of the form breaker 10. Thus, the spacer 26 can slidably move along the handle 12 so that the spacer, during the usage of the form breaker, will automatically be guided by the handle instead of free falling during operation. The spacer may be made of elastomeric material, wood or the like.

In horizontal type construction, where the form is to be broken away from the undersurface of a cast concrete ceiling, it is intended that the spacer member 23 would have an elongated handle 24 attached for the purpose of permitting the spacer to be repositioned across the surface of the form and concrete in the same manner as the form breaker 10 is moved across the surface by means of the handle 12. If the spacer 26 is mounted for slidable movement on the handle 12, the individual handle 24 for the spacer 26 can be mounted in parallel by suitable brackets 25 so that it can be slidably moved with respect to the handle 12.

The modification of FIGS. 7 and 8 includes a bladder 30, which is inflatable by means of an air line 31, and an outer flexing covering 32 of tough, resilient synthetic plastic such as polyurethane sheet, polypropylene sheet, nylon mesh reinforced polyethylene, other reinforced plastics, etc. The covering 32 is a sheet folded over the bladder 30 and is secured together at its open side 33 by means of a metal clamp means 34. The clamp is secured to the covering by means of rivets 37 or the like. The sides of the covering are closed by clamp members 39 held by rivets 40 or the like. The clamp members 39 are spaced from the upper clamp member 34 to permit the sides to swing inwardly as the bladder is inflated. This arrangement encloses the bladder in a tough resilient covering, but permits inflation and deflation of the same. The sides protect the edges of the inflatable member and/or its covering and aids in manipulating the inflatable member into position for use.

A rigid handle support 42 is secured by welding or otherwise to the clamp member 34, generally centrally thereof. A pair of U-bolts 43 with wing nuts 44 are arranged to releasably secure a handle 45 therein. The handle 45 may be long as necessary for the particular concrete forms being removed from the concrete, and may be made of solid or tubular material. Wooden handles are satisfactory, as are aluminum, magnesium, etc. solid or tubular stock.

The air line 31 is connected to an open sided pop-it valve arrangement, shown generally by numeral 46, which includes a relief valve 47 and a hole 48. An air line 49 from a compressor (not shown) supplies air to the air line.

For using this embodiment, the handle is attached to the handle support and tightened in place. The air line 49 is connected to a compressor. The breaker is then placed in between the form and the concrete, as explained above, with the wedge holding the form from the top of the concrete. With the air compressor providing air to tube 49, by closing the hole 48 with a thumb or finger, air pressure fills the bladder expanding it. Only about 10-30 pounds per square inch are necessary for sufficient inflation to break the form away from the concrete. Therefore, a small hole is easily covered by a thumb and such low pressure is easily held. The pressure relief valve 47 prevents overinflation of the bladder. The bladder is deflated easily by removing the thumb from the hole. Inflation is achieved by again placing the thumb over the hole. Thus, the bladder may be easily inflated and deflated for breaking a form away from the concrete. Also, the state of inflation is easily controlled by using a thumb for partially blocking the opening.

In the embodiments of the invention described herein, a satisfactory size of bladder is one in which the width of the bladder, which is the long dimension, may be 16 to 18 inches while the depth of the bladder, or the short dimension, is approximately 6 to 12 inches. With these dimensions, the bladder may easily fit between rows of tie wires through the forms. Other sizes may obviously be used. The rigid handle may be of any length which is sufficient to move the form breaker from edge to edge across or down the form for the structure. The bladder 11 may be made from any flexible, elastomeric material, (preferably very tough and puncture resistant) such as synthetic plastics (for example, polyurethane, polypropylene, etc.), synthetic rubbers or natural rubber which is air impermeable. The clamp device 15 and handle 12 can be formed from any suitable lightweight material such as aluminum, magnesium, fiberglass or plastics which can provide the necessary rigidity, yet be lightweight to permit a portable operation. The handle and means for holding the bladder must be rigidly connected, to permit movement of the bladder to the desired point of use, and preferably in the proper configuration, i.e., extending forwardly from the handle. The side clamps also aid in this.

While an inflatable form breaker device has been shown and described in detail, it is obvious that this invention is not to be considered as being limited to the exact form disclosed and that changes in detail and construction may be made therein within the scope of the invention without departing from the spirit thereof.

Claims

I claim:

1. An inflatable device for separating forms from cast cementitious construction, said device comprising:

a. a flexible, inflatable bladder means capable of being expanded from a generally flat, deflated configuration to an inflated configuration, said bladder means having a pair of flat planar sides in face engagement when deflated and connected to each other around their peripheral edges;

b. rigid backing means extending along at least one side of said bladder supporting said bladder for manipulation between a form and a cast cementitious construction;

c. tubular handle having holding means for attaching said handle to said rigid backing means; and

d. conduit means communicating with the interior of said bladder means inclusive of control means whereby said bladder means can be changed from the deflated to the inflated configuration as desired.

2. An inflatable device as defined in claim 1, being further characterized by spacer means insertable between said form and a surface of said cementitious construction, whereby said form can be separated from said construction by alternatively and progressively positioning said spacer means and said bladder means across the surface of said construction.

3. An inflatable device as defined in claim 2, wherein said spacer means is arranged for slidable movement on said tubular handle whereby the wedge means can move toward said bladder means when said bladder is extended to the inflated position holding the form spaced from the surface of the cementitious construction when the bladder is deflated and moved forward.

4. An inflatable device as defined in claim 2, wherein said handle is of sufficient length to progressively position said bladder from edge to edge of said cementitious construction.

5. An inflatable device as defined in claim 2, wherein said spacer means is formed of elastomeric material.

6. An inflatable device as defined in claim 2, wherein said spacer means includes an elongated handle which is of sufficient length to progressively position said spacer means across the surface of the cast cementitious construction.

7. An inflatable device as defined in claim 2, wherein said spacer means is reciprocably mounted on said tubular handle and moves downwardly by gravity when said tubular handle is held vertically.

8. An inflatable device as defined in claim 1, wherein said control means is arranged for alternately connecting said conduit to a compressor inlet and outlet for rapidly changing said bladder means from the inflated to the deflated configuration.

9. An inflatable device as defined in claim 1, wherein said control means is an opening in said conduit arranged to be opened and closed by a digit of the user.

10. An inflatable device as defined in claim 1, wherein said control means is a three way valve.

11. An inflatable device as defined in claim 1, wherein one said backing means includes clamp means for said bladder.

12. An inflatable device as defined in claim 1, wherein said bladder is of a length to easily fit between rows of tie wires through the forms.