US3153835A

US3153835A - Reinforced plastic molds

Info

Publication number: US3153835A
Application number: US215660A
Authority: US
Inventors: Karl C Schmocker
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-08-08
Filing date: 1962-08-08
Publication date: 1964-10-27
Anticipated expiration: 1981-10-27

Description

Oct. 27, 1964 K. c. 'scHMocKl-:R 3,153,835

REINFORCED PLASTIC MOLDS Filed Aug. 8, 1962 INVENTOR. KARL C. SCHMOCKER G14 e VM w 'l AT TORNE Y.

United States Patent O 3,153,835 RElNFRCEl) PLASTC MGLDS Karl C. Schrnoclrer, 1% Ward St., Norwalk, Conn. Filed Aug. 8, 1962, Ser. No. 215,66@ 9 Claims. tCi. 2S- 131) This invention relates to forms useful in the construction and related industries, and more particularly concerns molds used in forming poured concrete structures and component parts thereof.

Plywood forms commonly used for poured concrete are not suitable for contoured or irregularly shaped surfaces, nor do they produce smooth, non-grainy finishes on exposed concrete surfaces. In most cases known forms leave ragged edges and parting lines, thus requiring sandblasting or other finishing operations. Known methods for the pouring of concrete structures with irnproved surface finish, clean parting lines, and within the limits of relatively close tolerances, require production centers with highly specialized heavy equipment, machinery, and the use of heavy steel-reinforced molds fitted to the equipment. The complete molded concrete units must then be transported over greater or lesser distances from the production center to the building sites at substantial expense and with the risk of damage in transit.

An object of this invention is to provide improved mold forms of substantially rigid but relatively light-weight construction suitable for assembly and/or use near or at the building site and effective to produce precisely dimensioned concrete structures in plain, contoured or irregular shapes and with exposed surfaces produced directly in any desired finish.

With plywood forms or forms of a similarly suitable material, it is now proposed to provide the same with an improved reinforced plastic surfacing bonded thereto, together with structural features for providing supplemental locking of the plastic surfacing to the plywood base and t e further provision of means for preventing delamination of the plywood or other laminated base.

A further object of this invention is to provide molds in laminar form with facing portions which produce evenly fiat or pre-determined shapes of regular or irregular contour in poured concrete and reproduce any desired surface finish thereon.

Another object of this invention is to provide for the pouring of concrete, improved molds capable of repetitive assembly and disassembly, singly or in interfitting and interlocked groups, and capable of withstanding relatively high pressures and impacts during pouring and vibrating operations; such molds of laminar construction combining plywood or other laminated backing, plastic facing, and intermediate reinforced plastic bodies in a structure which results in a monolithic beam-type construction of the plastic body together with locking and interlocking features, which yield substantial strength and high resistance to delamination of the plywood and/ or the plastic Iarninae.

Other objects of this invention will in part be obvious and in part hereinafter be pointed out.

In the drawing, FIGURE 1 is a partial transverse section of a mold element embodying the invention;

FGURE 2 is a plan view thereof;

FGURE 3 is a sectional view showing a detail thereof;

FGURE 4 is a plan view thereof;

FIGURE 5 is a perspective view of a modified form of reinforcement.

it is understood that the molds of the instant invention are primarily of the type used in pouring substantial concrete building structures, or portions thereof, as for example, walls, arches, floors, and the like. The molds are supported and shored in a conventional manner Frice according to the volume of concrete to be poured and they do not utilize grease or similarly heavy and undesirable releasing aids as is usually applied to known steel or plywood forms.

FGURE l illustrates a portion of a flat mold made in accordance with the invention. Thus, on a table T there is disposed a pattern sheet with a pre-determined surface nisn 11 uppermost which is to be reproduced in the finished poured concrete structure. Pattern sheet 1t? may be of wood, plaster, resin, resin impregnated paper, fabric, and the like. As a preliminary step to mold production, the surface 11 is sprayed with a uniformly thin coating of a conventional release agent, not shown.

A uniform coating 12 of a polyester resin is applied over the release agent coating to a thickness of about 0.15 to .020; the polyester resin embodying, in addition to the conventional catalyst such as methyl ethyl ketone, a residual type of catalyst such as benzoyl peroxide in an amount of at least .5% by weight of the resin and a further inclusion of powdered electric conductive material such as carbon black in suspension and in an amount of from 0.5 to 2.6% based on the weight of resin. Coating 12 is then allowed to cure at about 70 F. for about one hour, to about 80% to 96% of complete cure.

A glass liber mat 13 weighing about l to 11/2 oz. per square foot and saturated with conventional catalyzed polyester resin is fitted over resin coat 12; residual air bubbles and excess resin are removed from the combination by squeegee or the like to maintain from about 25- 40% glass fiber content by weight. Care is taken to maintain such ratio and freedom from air bubbles in corner regions which, if necessary, are supplied with additional shredded glass iibers or fiber strands to preclude the forming of voids during the cure which takes place at this stage at about F. to produce an Sil-90% cure of the resin impregnant of the mat.

A glass fiber mat 14 impregnated with conventional catalyzed polyester resin and similar to mat 13 is applied over the incompletely cured mat 13.

The laminate consisting at this stage of partially cured resin coat 12, partially cured resin impregnated mat 13, and uncured resin impregnated mat 14, is not immediately subjected to further curing. After entrapped air and excess resin have been removed from mat 14 as heretofore mentioned, strips of glass ber rnat 15 saturated with catalyzed polyester resin are laid over mat 14, and entrapped air and excess resin are removed. Mat strips 15 are preferably between 16 and 20 wide when used in large at areas, otherwise are cut to fit the contours and shape of the mold, including provision for 2" `to 21/2" wide overlap regions on each side which form part of the beam-type reinforcement construction as will become apparent in the further description. The strips 15, whether straight or contoured, correspond to strips 16 of 3A plywood or other suitable material which are laterally related and spaced about 1/8 to 3/16" and are disposed over the part or parts of the mold which are to be heavily reinforced. Strips 16 are of reduced width and length so that marginal portions of strips 15 may be folded over the side and end edges of strips 16.

Thus, lateral edge portions 17, 1S of strip 15 extend about the edges 19, 2li of plywood strip 16 with the

marginal portions

21, 22 of ystrip 15 disposed over the margins of exposed surface 23 of plywood strip 16 and extended towards each other. lt is understood that as many mat strips 15 and corresponding plywood strips 16 are used as may be necessary to cover the total reinforcement area, and that the individual ystrip assemblies are moved under slight pressure towards each other to bring them into abutting relation, as shown in FlGURE l, with the space between plywood strips 16 solidly filled with glass ber reinforced plastic as shown. AIt is under- 3 stoodthat marginal end portions of iiber strip 15 are similarly folded about the ends of plywood strips 16.

Batten strips 24 of fiberglass roving or cloth about "-6 wide are laid over the joints formed by and over the adjacent

marginal portions

21, 22 of strips 15. Strips 24 are impregnated with catalyzed polyester resin, and entrapped air and excess resin are removed. The assembly thus providing reinforced plastic I-beams which are continuous with the reinforced plastic mold portions; form an integral part thereof, and are abutted by plywood strips 16 which are thus locked in place while the web portion of the plastic I-beam is locked in between the plywood strips.

The assembly described above may be provided with additional reinforcements for the attachment thereto of conventional shoring, supports, alignment means or the like. In such case, as shown in FIGURE 3, the plywood strips 16 are, prior to placement on mat strips 15, provided with thimbles 25 at spaced intervals along a predetermined extent of the desired reinforcements. Thimbles 25 are threaded for the purpose later described. Care is taken to irnbed the thimbles well within the plywood strips and to fill any void with resin impregnated shredded berglass to preclude pressure against the said facing layer or an air pocket between that layer and the plywood. Before further steps are taken toward assembly, the laminate mold structure is subjected to pressure, such as may be produced by clamping devices, or other pressure or vacuum systems. The resin coating 12 and resin impregnated mats 13, 14, as Well as

strips

15, 24 have been sequentially cured as previously described. The assembly, with or without thimbles 25, is then subjected to a conventional post-cure at about 110 to 120 F. and thus the entire laminate is substantially stabilized with a minimum, if any, distortion or imperfection of the resin molding surface l2 which is highly resistant to damage by alkali emanating from the poured concrete. The cured assembly may now be removed from table T, being stripped away from pattern sheet 10.

When the assembly is to be provided with further reinforcements, and thimbles 25 have been previously located on plywood strips 16, then studs 26 are screwed into thimbles 26 and beams 28, such as 2 x 4s or the like, are bored at longitudinally spaced intervals to receive studs 26. Nuts 27 on the upper ends of studs lock the beams 23 in place against the rear surfaces of plywood strips 16. It is understood that beams 28 may be arranged in various grid patterns as desired or necessary to cope with expected stresses and alignment conditions. It is also understood that when such reinforcing members are used and may be exposed to water or dampness, then the exposed surfaces thereof are coated with lsuitable water repellent material.

In lieu of the above described solid beam reinforcements 28, an alternative reinforcement in accordance with this invention takes the form of a channel of reinforced plastic, of inverted U or V cross section, as illustrated in FIGURE 5, wherein a preformed ilexible strip of urethane foam 29 or similarly suitable material is positioned and suitably fastened to the rear of the laminar mold previously described, in grid patterns, including curved and variously shaped sections. Strip 29 then is covered with one or more layers 30 of curable resin impregnated fiber mat including flange portions31, 32 which are bonded to the mold proper. The reinforcement is then bonded inplace and cured together with the laminar mold during the last cycle of the sequential curing resin operations prior to the final cure of the overall assembly.

The preliminary partial cure of the resin impregnated fiberglass laminates, performed sequentially as the assembly of the mold progresses, insures minimal internal strains and correspondingly desirable surface conditions for the production of finely grained concrete cement structures. On relatively large surfaces, of 20 square feet or more, the catalyzation of the resin and its application during the production process is varied whereby the catalytic action in at least two predetermined areas is more active than in other areas, and the strains and shrinkage resulting from the first occurring curing process are diverted into areas of somewhat later curing to preclude undesirable transmission of buckling or warping forces between opposite edges or corners.

While various changes might be made in the embodiments of the invention herein disclosed without departing from the spirit thereof, it is understood that all of the matter herein shown or described shall be deemed illustrative and not by way of limitation except as set forth in the appended claims.

What is claimed is:

l. A form member of extended surface area for poured concrete structures comprising a laminate including a facing layer of synthetic resin, a plurality of laterally related plywood reinforcing strips for backing said resin facing layer, and resin impregnated glass fiber structures between said strips and said facing and in bonded relation thereto, said fiber structures including marginal portions extending about the edges and marginal portions of said strips.

2. A form member for poured concrete structures comprising a laminate including a facing layer of synthetic resin having a patterned outer surface, resin impregnated glass fiber structures having at outer surface portions thereof in bonded relation to the inner surface of said facing layer, plywood strips overlying inner fiat surface portions of said fiber structures and bonded thereto, said ber structures including marginal edge portions thereof wrapped about the lateral edges of said strips and bonded thereto.

3. A form member as in claim 2 wherein said glass fiber structures comprise a plurality of mats in side by side relation, a plywood strip associated with each mat, the marginal edge portions of each mat being wrapped about the marginal edges of the associated strip, and glass liber strips overlapping adjacent oppositely extending marginal edge portions of adjacent rovings and in bonded relation thereto.

4. A form member for poured concrete comprising a smooth finish facing layer of synthetic resin, plywood reinforcing for said facing layer and including a plurality of plywood strips having their lateral edges in adjacent relation to each other, resin impregnated glass fiber structures in bonded relation to said facing and said plywood strips, said fiber structures including resin impregnated glass fiber in contacting relation with said resin facing, resin impregnated glass fiber mat in contacting relation to said fabric, and a plurality of resin impregnated glass fiber mats in side by side relation, each mat having marginal portions thereof wrapped about the edges of an associated plywood strip, the marginal portions of adjacent mats having abutting portions, and resin impregnated fiber strips in bonded relation to the rear surface of marginal portions of adjacent plywood strips, said fiber strips overlying marginal edge portions of adjacent first mentioned mats.

5. A form member as in claim 4 and further including elongated reinforcement members disposed over the rear surface of said plywood strips and means for securing said reinforcement members to said plywood strips.

6. A form member for poured concrete comprising a laminate including a facing layer of synthetic resin having a thickness of from about .015 to about .020, a resin impregnated fiber glass backing layer for said facing layer, and, reinforcing strips overlying said backing, said backing layer comprising a plurality of adjacent mat strips respectively underlying said reinforcing strips, said mat strips including marginal portions wrapped about the edges of said reinforcing strips.

7. A form member for poured concrete comprising a laminate includingja facing layer of synthetic resin having a predetermined outer finish, a plywood backing comprising a plurality of laterally adjacent plywood strips, a fiber glass layer between said resin facing layer and said plywood backing, said ber glass layer comprising superposed resin impregnated mats and resin impregnated mat strips between each plywood strip and said mats, said mat strips having marginal portions folded about the marginal edges of said plywood strips, the resin impregnated mats and mat strips being cured in situ.

8. A form member for poured concrete structures comprising a laminate including a facing layer of synthetic resin, a plurality of laterally related reinforcing strips, and resin impregnated glass liber structures between the said strips and said facing layer and in bonded relation thereto, said ber structures including portions extending about the edges and marginal portions of said reinforcing strips in interlocking and mutually reinforcing relation.

9. A form member for poured concrete structures comprising a laminate including a facing layer of cured synthetic resin, a plurality of laterally related reinforcing strips in opposed relation to the rear surface of said facing layer, and a ber reinforced synthetic resin body bonded to said strips and said facing layer, said resin body including portion of I-bearn section between adjacent edge 10 portions of said reinforcing strips.

Wells Apr. 14, 1925 Sperry May 11, 1948

Claims

1. A FORM MEMBER OF EXTENDED SURFACE AREA FOR POURED CONCRETE STRUCTURES COMPRISING A LAMINATE INCLUDING A FACING LAYER OF SYNTHETIC RESIN, A PLURALITY OF LATERALLY RELATED PLYWOOD REINFORCING STRIPS FOR BACKING SAID RESIN FACING LAYER, AND RESIN IMPREGNATED GLASS FIBER STRUCTURES BETWEEN SAID STRIPS AND SAID FACING AND IN BONDED RELATION THERETO, SAID FIBER STRUCTURES INCLUDING MARGINAL PORTIONS EXTENDING ABOUT THE EDGES AND MARGINAL PORTIONS OF SAID STRIPS.