US2493264A - Movable form for concrete masses - Google Patents

Description

W. M. RECORDS MOVABLE FORM FOR CONCRETE MASSES Jan. 3, 1950 3 Sheets-Sheet 1 Filed Sept. 7, 1946 INVENTOR WILLIAM M. RECORDS Jan. 3, 1950 vy. M. RECORDS MOVABLE FORM FOR CONCRETE MASSES 3 Sheets-Sheet 2 Filed Sept. 7, 1946 INVENTOR S D R O C E M m) U M m I w mr W. M. RECORDS MOVABLE FORM FOR CONCRETE MASSES Jan. 3, 1950 3 Sheets-Sheet 3 Filed Sept. 7, 1946 QN N NN INVE QTOR WILLlAM M.RECORDS Patented Jan. 3, 1950 MOVABLE FORM FOR CONCRETE MASSES William M. Records, Pittsburgh, Pa., assignor to Blaw-Knox Company, Pittsburgh, Pa., a corporation of New Jersey Application September 7, 1946, Serial N 0. 695,409

This invention relates to forms for concrete masses and, in particular, to forms used in the construction of masses comprising a plurality of superposed layers, such as dams or the like.

In the construction of concrete masses by pouring a plurality of layers successively one on the other, it is customary to employ sectional forms, each section of which comprises a panel'secured to stringers or beams extending downwardly therefrom for anchorage to a layer already cast. With such forms as heretofore constructed it has been found difficult or impossible to maintain the faces of the structure in the desired plane. In the case of a dam, for example, the downstream face of which usually has a substantial slope, the beams or stringers supporting the form panel are necessarily subject to slight deflection because they are loaded as cantilevers. As a result, the face of each layer above the bottom dips slightly relative to the slope of the face of the previously cast layer and this efiect is cumulative from layer to layer. In the case of the form for the upstream face of the dam which is usually substantially vertical, the eiTect of deflection is not serious but it is sometimes desirable to change the slope of the face from one layer to the next and this is difficult with the forms known heretofore.

I have invented an improved form particularly adapted for the construction of concrete masses cast in successive layers, which overcomes the aforementioned objections and permits the face of the finished structure to be made precisely plane or curved to the desired extent. In a preferred embodiment, I provide a form panel hinged adjacent lower edge to a pair of stringers or supporting beams, adapted to be secured to a layer already cast. I mount adjusting screws near the upper ends of the stringers for shifting the panel relative thereto about its pivotal axis to bring the upper edge of the form to the exact position necessary either to maintain the face of the structure in a given plane or impart a desired curvature thereto by changing the angle of the faces of successive layers. H

I also provide novel means for raising the forms after the casting of one layer, into position for the casting of the next layer thereabove' Specifically, I employ outriggers attachable to the beams or stringers of the form whereby the form panel is automatically tilted away from theface of the layer of concrete cast thereagainsuand is thus progressively stripped prior to being elevated into position for the next layer. This feature is of 1 Claim. (Cl. 25-131) particular importance in the form used on the face of the structure having a decided slope, such as the downstream face of a dam, since the form used in that position exerts a considerable vertical component of force against the concrete structure because of its weight and the slope of the face.

A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanying drawings illustrating a present preferred embodiment. In the drawings,

Figure 1 is a cross section through a dam showing forms according to my invention secured to the upstream and downstream faces of a previously cast layer and in position for the casting of the next succeeding layer;

Figure 2 is an elevation of one of the forms, e. g., that for the upstream face, with parts omitted for the sake of clearness;

Figure 3 is a partial plane view of the form with a part in section along the plane of line III-III of Figure 2;

Figure 4 is a view similar to Figure 1 to reduced scale showing the arrangements for lifting the forms after the casting of a layer therebetween; and

Figure 5 is a partial perspective view of a detail.

Referring now in detail to the drawings and for the present to Figures 1 through 3, a concrete mass, such as a dam for the construction of which the form of my invention is adapted, may comprise a plurality of superposed layers Ill, ll, etc. extending upwardly from the foundation to the desired height, the several layers being secured together by suitable means and the joints therebetween sealed against the entrance of water. In the case of the dam illustrated, the successive layers composing the complete structure are cast between sectional forms l2 and I3 on the upstream and downstream faces l4 and i5, respectively, of the structure. These forms are generally similar except that the form l3 has a greater width because of the inclination of the downstream face l5. Each form comprises a generally rectangular panel IB carried by beams or stringers ll secured to and extending upwardly from the layer ll previously cast. It will be understood that a number of the forms illustrated are disposed side by side in end abutting relaq tion, depending on the total length of the structure, i. e., in the case of the dam the width of the stream or valley to be closed off.

Considering in particular the form l2, the panel I6 thereof is composed of a plate l8 secured to spaced horizontal ribs IS. The ribs l9 are secured to a pair of spaced cross members 20. The stringers I! are composed of spaced channels 2| and the cross members 20 are disposed therebetween. The panel is hinged to the stringers adjacent its lower edge by bolts 22 extending through the webs of the channels 2| and the cross members 20. Shoes or bearing blocks 23 secured to the lower ends of the stringers are adapted to engage the base I4 of the previously cast layer I I and also serve to secure the channels 2| together in spaced relation. An angle 24 extending across the bottom of the panel has one flange bearing against the face I4 at the upper edge of the layer H. The stringers are secured to the latter by screw anchors 25 extending through cross plates 26 bridging the channels 2|. A bearing pin 21 extends through the webs of these channels below the shanks of the anchors to support them when the form is being raised. Additional screw anchors 28 extend through holes in the flanges of a short length of channel 29 secured to the cross members 20 adjacent their upper ends and through holes in the plate I8. The anchors 25 extend into holes in the layer II formed by the anchors 28 during the casting thereof, the anchors being unscrewed before the final setting of the concrete, leaving threaded bores for receiving the anchors 25.

Referring now particularly to Figure 3, adjusting screws 30 are threaded through nuts 3| welded to plates 32 bridging the channels 2| at their upper ends. The shanks of the screws extend through lugs 33 welded to the cross members 20 and have thrust collars 34 welded thereto on opposite sides of the lug. It will be evident that this arrangement permits the panel I6 to be tilted bodily relative to the stringers IT by turning the screws 36. This permits the upper edge of the form panel to be brought precisely to the position necessary either to maintain the face I4 of the dam plane or to give it a desired increased or decreased angle to the vertical should that be desired.

It will be obvious that the connection between the panel and stringers provided by the screws 30, nuts 3|, lugs 33, and collars 34, provides for limited angular deflection of the panel with respect to the stringers as well as adjustment of their relative locations. This is due to the fact that some bending of the screws 3|] may occur, as well as to the clearances between the parts permitting some angular deflection without introducing bending stresses. In fact, this construction constitutes a hinge which may, if desired, be used in the lower side of the panel in place of the fixed hinge 22. In this case some adjustment of the lower edge of the form with respect to the face of the wall may be provided by adjusting the hinge which thereafter acts as a pivot when the upper edge of the form is adjusted in the manner previously described.

The form I3 needs no further description except to refer to the wheels 35. These wheels are journaled on levers 35a pivoted to the channels 2| at 351) and are normally spaced from the face I5. The levers 35a have wood bearing blocks 350 which engage the layer II when the levers are in the position shown in Figure 1. Jack screws 35d threaded through nuts on the stringers engage cross angles 35c connecting the levers 35a for effecting slight tilting thereof to bring the wheels 35 into engagement with the face I after the form has been stripped and is ready for upward movement. Both forms I2 and I3 have working platforms 36 supported by angles 31 and 38 secured to the stringers. Lifting loops or eyes 39 are provided at the upper ends of the stringers by welding to the channel 2| pieces of bar bent to U-shape.

With the forms I2 and I3 in the positions shown in Figure 1, it will be apparent that concrete may be poured therebetween to the level indicated by chain line 40, thus providing an additional layer indicated at 4| in Figure 4. After this layer has partially set, the anchors 28 are unscrewed as previously described. When the layer 4| has completely set, the forms I2 and I3 may be stripped and lifted into position for the pouring of the next higher layer. For lifting the form I2, I provide an A-frame 42 provided with a lever-operated ratchet hoist 43. The A-frame has backstays 44 extending from the upper end thereof to anchor loops 45 embedded in the top surface of the layer 4|. When the chains from the hoist 43 have been attached to the loops 39 of form I2, the anchors 25 are unscrewed and the form is hoisted bodily to the position shown in chain lines in Figure 4. The pins 21 support the anchors 25 at the proper angle during the hoisting of the form so they may easily be turned into the bores formed by the anchors 28, to secure the form in position for the next cast. Since the face I4 is nearly vertical, the form I2 may easily be stripped by pressure applied manually or by the use of a crow-bar, since the weight of the form is carried entirely by the hoisting chains.

The lifting of the form I3 is accomplished by similar means with the addition of Outriggers 46 adapted to be attached to the stringers i'I by pins 4i.v Each outrigger comprises a short length of channel 48 fitting between the flanges of one of the channels 2| and having a tapered piece of plate 49 welded to the upper end thereof at an angle. An A-frame 50 provided with backstays 5! has a hoist 52 adapted to be connected to the end of the plates 49 of the Outriggers. Before lifting the form, it is stripped by turning down the jack screws 35d. The bearing blocks 350 are thereby forced against the face I5 of layer I I and the reaction causes progressive stripping of the form. On continued turning of the screws, the wheels 35 engage the face I5. When the hoist 52 is operated, the force supplied to the outriggers tends to tilt the form about the wheels so that it clears the face I5 at all points. Thereafter, operation of the hoist 52 causes the form to travel upwardly over the face I 5 on the wheels 35. When the forms have been raised to the proper height for the casting of the next layer, the anchors 25 are turned into the holes left in the previous layer by the anchors 28 and the jack screws 35d are backed off to permit the bearing blocks 350 to engage the face I5, leaving the wheels 35 spaced slightly therefrom.

It will be apparent from the foregoing description that the invention is characterized by important advantages over movable forms as heretofore constructed. In the first place, the hinged mounting of the form panel on the stringers or cantilever beams permits the faces of the layers to be maintained at the proper angles to the vertical and also permits variation in these angles from layer to layer, if desired. The Outriggers fa cilitate the stripping of the form for the downstream face which is at an angle such that the weight of the form resists the stripping force. The mounting of the wheels on tilting levers having bearing block permits the latter to distribute over a substantial area the reaction incident to stripping while the wheels permit traveling movement of the form without excessive friction. The location of the wheels adjacent the lower edge of the form panel, furthermore, permits the use of Outriggers of a minimum length. This length is controlled by the intersection of the line through the wheel normal to the face l5, the vertical line through the center of gravity of the form and the line of pull of the hoist.

Although I have illustrated and described but a preferred embodiment of the invention, it will be recognized that changes in the details thereof may be made without departing from the spirit of the invention or the scope of the appended claim.

I claim:

A movable form comprising a panel, a pair of beams on which the panel is mounted extending downwardly therefrom, levers pivoted to said beams adjacent the lower edge of the panel, hearing blocks on said levers, and wheels journaled on the levers, the bearing blocks and wheels being adapted to be presented alternately to a supporting surface on tilting of said levers.

WILLIAM M. RECORDS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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