Patent Application
20220314490
The present disclosure relates generally to a mold assembly for molding in one production cycle two concrete blocks in face-to-face non-contacting relationship and to a method of manufacturing concrete blocks.
Retaining walls are used in various landscaping projects. Typically, they are used to maximize or create level areas and also to reduce erosion and slumping. They may also be used in a purely decorative manner. In recent years, segmented concrete retaining wall blocks, which are dry stacked without the use of mortar, have become widely accepted in the construction of retaining walls.
Typically, retaining walls are constructed with multiple courses of blocks. More recently, retaining wall construction has become significantly simplified with the introduction of self-aligning blocks that may be stacked in courses without the use of mortar or extensive training. With these types of retaining wall blocks, it is possible to erect a retaining wall quickly and economically, and the erected retaining wall creates the appearance, of a conventional block-and-mortar retaining wall.
In the manufacture of retaining wall blocks on a commercial scale, a common practice in the industry has been to mold the blocks as paired units in which two blocks are molded in face-to-face contact as a single unit and after curing, the paired blocks are mechanically split apart at their adjoining faces to form two individual blocks having rough fracture surfaces which resemble the appearance of a “split” rock. The rough fracture surfaces on the front faces of split blocks may be aesthetically pleasing in some applications, however other applications prefer or even require blocks having smooth front faces. Also, when splitting paired blocks, it is difficult to create distinct, uniform boundaries around the perimeters of the split faces, which detracts from the aesthetic appearance of retaining walls erected with split blocks.
This disclosure relates to an improved mold assembly and method for molding two concrete blocks in face-to-face non-contacting relationship to form blocks having smooth front faces.
In accordance with one aspect of this disclosure, two mold cavities are configured to form two blocks in face-to-face non-contacting relationship, wherein a common partition plate separates the two mold cavities and opposite sides of the partition plate form the smooth front faces of the blocks.
According to another aspect, each mold cavity is configured to form a beveled edge around the entire perimeter of the smooth front face to form a block having a raised front face.
According to another aspect, each mold cavity is configured to form a border around the entire perimeter of the beveled edge of the block to enhance the three-dimensional effect created by the raised front face.
According to a further aspect, the two mold cavities are each configured to form a block having a raised front face with a beveled edge around its entire perimeter and a border around the entire perimeter of the beveled edge. The portions of the border at the top and the sides of the raised front face are curved and the portion of the border at the bottom of the raised front face is straight.
In accordance with another aspect, a method of molding two concrete blocks in face-to-face non-contacting relationship includes providing a mold box having two face-to-face mold cavities that are mirror images of one another. The mold cavities are separated by a partition plate having opposite smooth surfaces that conform to smooth front faces of blocks formed in the mold cavities. The mold cavities are placed on a pallet which closes the open bottoms of the mold cavities after which the mold cavities are filled with a dry cast concrete mixture. A stripper shoe assembly attached to a compression head is situated above the open tops of the mold cavities, and the compression head is lowered to insert stripper shoes into the open tops of the mold cavities to compact and densify the concrete mixture. After densification, blocks having smooth front faces are discharged from the mold cavities and transported to another location for curing.
According to another aspect, a core bar is slidably inserted into the mold box beneath the bottom of the partition plate, and opposite sides of the core bar extend into and form the front bottom portions of the mold cavities. The core bar sides are configured to form blocks having straight edges at the bottoms of the raised front faces. The side portions of the mold cavities are configured to form curved edges at opposite sides of the raised front faces, and the bottom surfaces of the stripper shoes are configured to form curved edges at the tops of the raised front faces.
The figures in the drawings are simplified for illustrative purposes and are not necessarily depicted to scale. In some figures, parts have been enlarged relative to other parts to facilitate describing and understanding this disclosure. The same reference numerals have been used, where possible, to designate identical elements that are common to the figures, except that suffixes may be added, when appropriate, to differentiate such elements. The drawings and written description omit describing some parts that are well known in the industry and not needed for understanding this disclosure in order to simplify a reading and understanding of this disclosure.
The drawings illustrate exemplary embodiments of the disclosure and, as such, should not be considered as limiting the scope of the disclosure that may admit to other effective embodiments. It is contemplated that features or steps of one embodiment may be beneficially incorporated in other embodiments without further recitation.
The term “exemplary” is used herein to mean “serving as an example, instance, or illustration”. Any embodiment or design described herein as “exemplary” or “alternative” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.
The present disclosure relates to a mold assembly for molding two concrete blocks in face-to-face non-contacting relationship and to a method of manufacturing concrete blocks. While the following description relates to dry cast retaining wall blocks, it is understood that the disclosure is not limited thereto and may be applicable to forming other types of concrete blocks. Unlike prior art techniques in which two blocks are molded in face-to-face contact as a paired unit, sometimes referred to as “Siamese” twins, and then split apart at their joined front faces to form two individual blocks having rough fracture surfaces, this disclosure describes forming two individual blocks in face-to-face relationship in which the front faces of the blocks are spaced apart and not joined together, thereby obviating the need for splitting them apart and simplifying formation of blocks having smooth front faces.
As shown in
In the embodiment illustrated in
Retaining wall blocks of this general type are disclosed in U.S. Pat. No. 7,963,727 assigned to E. Dillon & Company, which is incorporated herein by reference in its entirety. The blocks disclosed in this patent are molded in paired units, with the front sections of both blocks of each paired unit joined along an imaginary interface in face-to-face relation. After curing, grooves are formed, for example, by grinding, in the bottom surfaces of the joined blocks following which each paired block unit is split into two individual blocks. The splitting process forms a rough textured surface on the front faces of the blocks. The front face of each panel terminates at the top and at opposite sides in curved edges and terminates at the bottom in a flat edge. The front faces of the blocks are divided into two panels of different widths and the front faces of the panels have rough fracture surfaces due to their formation by splitting. The bottoms of the panels terminate at the bottom surfaces of the blocks with no border at the bottom marginal edge portions of the panels.
Unlike the method of forming retaining wall blocks disclosed in U.S. Pat. No. 7,963,727 in which the blocks are molded in paired units and then split to form individual blocks, this disclosure relates to molding two blocks in face-to-face relationship using a common partition plate that separates the two mold cavities and that forms the smooth front faces of the blocks
To facilitate a description of the mold assembly in accordance with aspects of this disclosure, a description will first be given of features of the blocks 2 that are formed by the mold assembly. As shown in
The front, faces of the panels 23, 24 are raised with respect to the borders by an amount equal to the thickness of the beveled edges 23a, 24a. By way of example, it has been found that for 18-inch wide blocks (blocks whose, front surface measures 18 inches from side to side), beveled edges having a thickness of 0.25 inch raise the front face of the block a sufficient distance from the surrounding border to achieve a pronounced three-dimensional appearance. This thickness, of course, is not a requirement and this disclosure is applicable to blocks whose raised front faces have thicknesses greater or less than 0.25 inch, preferably in the range 0.20 inch to 0.30 inch, as well as to blocks of different sizes and dimensions. Further by way of example, the curved borders at the tops and both sides of the panels 23, 24 and the straight borders at the bottoms of the panels have widths substantially greater than the thickness of the beveled edges, preferably widths in the range 0.40 inch to 0.55 inch for 18-inch wide blocks. The widths of the borders are measured in the vertical plane of the panel front faces, i.e., in a direction perpendicular to the thickness direction of the beveled edges. When retaining wall blocks 2 are stacked in courses one atop another to erect a retaining wall, the raised front faces noticeably stand out in relief from their surrounding borders creating an aesthetic three-dimensional effect. As described hereinafter, the front faces of the panels 23, 24 have a smooth texture because they are formed by the smooth surfaces of the partition plate during molding and not by splitting.
One embodiment of a mold assembly for molding block pairs in face-to-face non-contacting relation in accordance with principles of this disclosure is shown in
Each mold compartment 76, 77 has a mold cavity 80 having a shape that conforms to the outer surfaces of the block molded therein. The two mold cavities 80 are separated by the partition plate 75 and have configurations that are mirror images of one another. In this example, the partition plate 75 has smooth opposite surfaces to form blocks having smooth textured front faces. As used herein, “smooth faces” or “smooth surfaces” of the partition plate 75 refer to the surface texture of the partition plate surfaces and the corresponding surface texture of the front faces or surfaces of the blocks when discharged from the mold cavities 80 with no other device, element or action altering the block front faces or surfaces. The smooth surfaces of the partition plate have a flat and even consistency, free from perceptible projections or indentations, such as weld spots or other surface defects, that could mar the front faces of the blocks so that the block front faces have a smooth and uniform appearance throughout.
Mold parts 81 are provided in the mold compartments 76, 77 and have shapes that conform to the shapes of the side surfaces of the blocks. The inner surfaces of the end walls 73,74 have planar shapes that conform to the planar shapes of the rear surfaces of the blocks. The inner surfaces of the end plates 73, 74 are provided with vertically extending mold parts 78 configured to form the score grooves 43 on the rear surfaces of the blocks. The mold parts 81 may be formed by machining out a mild steel block, such as by plasma arc cutting or flame cutting, to form the side surfaces of the mold cavities 80, and/or some mold parts may be in the form of machined wear plates or end liners
The mold box 70 is provided with two core assemblies, one in each mold compartment 76, 77, to form the through-cavities 50 in the blocks. As illustrated in
When forming split-face blocks, mold parts 83 are provided on the opposite faces of the partition plate 75 as shown in
In a like manner, the mold parts 81 in the mold compartments 76, 77 have shapes that correspond to the shapes of the side surfaces of the blocks and of the comers where the side surfaces meet the front surfaces of the blocks. The mold parts 81 each have curved edge portions 81a which have a shape that conforms to the shape of the curved edge portions 23b, 24b at the front corners of the block, and beveled portions 81b extending inwardly from the curved corner edge portions 81a and which have a shape that conforms to the shape of the beveled edges 23a, 24a at the outer sides of the panels 23, 24.
As shown in
As shown in
Another core bar 86 is situated directly beneath the partition plate 75 between the two core bars 85. The core bar 86 is slidably insertable through an opening in the side wall 72 and slidably engages with the underside of the partition plate 75. The sliding engagement between the core bar 86 and the partition plate 75 may be implemented by complementarily-shaped male and female parts, one provided on the partition plate 75 and the other provided on the core bar 86. As shown in
The opposite faces 75a of the partition plate 75 have a smooth surface which conforms to the smooth front faces of the panels 23, 24 of the block. The core bar 86 has opposed upper surface portions 86a which are coplanar with the opposed surfaces 75a of the partition plate 75 when the core bar 86 is insert into the mold box and which form the lower portions of the front faces of the panels, The core bar 86 has opposed beveled surfaces 8Gb configured to form the beveled surface 23a, 24a along the bottom edges of the panels 23, 24, and opposed straight surfaces 88c configured to form the straight borders 23c, 24c along the bottom edge portions of the panels 23, 24.
As illustrated in
During a production cycle, a compression head is positioned above the mold box 70 to apply pressure from above to the concrete mixture loaded into the mold cavities 80 and to assist in discharging the blocks from the mold cavities when the production cycle is completed,
When forming two face-to-face non-contacting blocks in a production cycle, a flat production pallet made of steel, plastic, or wood, for example, is positioned beneath the mold box 70 to close the bottoms of the mold cavities 80. After positioning the pallet beneath the mold box 70, the core puller CP is actuated to slidably insert the core bars 85, 86 into the mold box 70 to complete formation of the mold cavities 80 (
In beginning a production cycle, an appropriate amount of concrete mixture from a hopper is loaded, via one or more feed drawers, into the mold cavities 80. The process and equipment for transporting the concrete mixture and loading it into the mold cavities are well known in the art. The concrete mixture in the mold cavities 80 is next compacted or consolidated to densify it. This is accomplished primarily through vibration of the concrete mixture in combination with the application of pressure exerted on the concrete mixture from above by the compression head 90. The vibration can be exerted by vibration of the pallet underlying the mold box (table vibration), or by vibration of the mold box (mold vibration), or by a combination of both actions. The pressure exerted by the compression head is transmitted by the stripper shoes 91 that contact the concrete mixture from above. The downward pressure exerted on the stripper shoes 91 forms the top surfaces of the blocks, i.e., forms the protuberances 12 on the top surfaces 4 of the blocks and the curved borders 23b,24b and the beveled edges 23a, 24a on the tops of the panels 23, 24. The downward pressure on the concrete mixture also forms, using the mold parts 81, the curved edge portions 23b, 24b at the front corners of the blocks and the beveled edges 23a, 24a at the outer sides of the panels 23, 24. If split-shaped blocks are being formed, the mold parts 89 are secured to opposite faces of the partition plate 75 to form the simulated dress joint 25 between the panels 23, 24.
The timing and sequencing of: vibration and compression is variable, and depends upon the characteristics of the concrete mixture and the desired results. The selection and application of the appropriate sequencing, timing and types of vibrational forces are within the ordinary skill in the art. Generally, these forces contribute to fully filling the meld cavities so that there are not undesired voids in the finished blocks, and to densifying the concrete mixture so that the resulting finished blocks will have the desired weight, density and performance characteristics. After densification, the pre-cured blocks are discharged from the mold assembly. Preferably, discharge occurs by actuating the core puller CP to withdraw the core bars 85, 86 from the mold box 70 and thereafter lowering the pallet relative to the mold box while further lowering the stripper shoes 91 through the mold cavities 80 to assist in stripping the pre-cured blocks from the mold. The stripper shoes 91 are then raised upwardly out of the mold box 70 and the compression head 90 is raised in readiness for repeating the production cycle.
The mold assembly has been described with reference to a small pallet machine that uses pallets only large enough to make one pair of blocks each production cycle. This disclosure is not limited to making only two blocks per production cycle and is applicable to what is referred to in the industry as “big board machines” which make four pairs (eight blocks) per production cycle. In the case of big board machines or other machines that make multiple block pairs per cycle, plural pairs of mold cavities are arranged in end-to-end relation with the end walls being formed as division or partition plates between adjacent face-to-face pairs of mold cavities. In such big board machines, the partition plates 70 and the core bars 85, 86 are formed from steel bars that are welded to a mold bottom plate referred to in the industry as a drawplate. An advantage of the big board machine is that the core bars are permanently secured to the mold bottom plate and there is no need to reciprocatingly slide the core bars into and out of the mold box
It will be appreciated by those in the art that obvious changes can be made to the examples a embodiments described in the foregoing disclosure, It is understood that this disclosure is not limit d to the particular examples and embodiments disclosed, but is intended to cover all obvious changes and modifications thereof which are within the scope of the disclosure as defined by the appended claims.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16247073 | Jan 2019 | US |
| Child | 17844700 | US |
