Method and system for cracking a flexible mold of dried wet-cast concrete products

The problem of wet-cast concrete products getting stuck in a flexible mold during demolding is solved, prior to demolding the wet-cast concrete products, by removing a vacuum on the flexible mold by moving at least one side edge of the flexible mold away from a part of the flexible mold that is adjacent to the at least one side edge in a direction opposite the open side of the flexible mold.

FIELD

The present disclosure concerns concrete molded product manufacturing. More specifically, the present disclosure is concerned with a method and system for cracking a flexible mold of dried wet-cast concrete products.

BACKGROUND

Precast concrete is a well-known construction product produced by casting concrete in a reusable mold or “form”, which is then cured in a controlled environment. There are mainly two common methods of manufacturing precast concrete products: the dry-cast method and the wet-cast method. Both methods create a simulated natural cut stone look and are used in manufacturing a variety of products such as: paving stones, bricks, veneer bricks, retaining wall bricks, steppingstones, etc.

As its name would imply, wet-cast concrete is more liquid. It has a high slump, which gives it the ability to be poured from a mixer or hopper. Also, in wet-cast a rubber mold is used. In contrast, dry-cast concrete is very dry, has zero or near-zero slump, and the forms can be stripped as soon as the concrete has been consolidated.

The dry cast manufacturing process typically involves complex machinery. Dry-cast concrete contains only enough water to hydrate the cement. The mix is compressed in a mold with very high pressure and then cured on a rack before being palletized and processed.

To manufacture wet-cast products, concrete is poured into a flexible mold and then vibrated to release air bubbles out of the mix. The mold then gets stripped after the concrete has cured.

De-molding in wet-cast is usually done by raising the mold, face-down, from a table or conveyor, or by peeling the mold.

While such de-molding process works fine with sufficiently large and heavy products, which simply stays on the table while the mold is removed, it has been found that smaller products get stuck in the mold.

This is caused by the concrete actually creating a vacuum on the mold, resulting in a tight connection between the products and the mold.

It results that current demolding of wet-cast concrete products, especially of relatively small products, cannot be automated and requires extra labor.

A demolding method and system that is free of the above drawback is therefore desirable.

SUMMARY

The problem of wet-cast concrete products getting stuck in a flexible mold during demolding is solved, prior to demolding the concrete products, by removing a vacuum on the flexible mold by moving at least one side edge of the flexible mold away from a part of the flexible mold that is adjacent to the at least one side.

The action of removing the vacuum on a flexible mold having dried wet-cast concrete products therein will be referred to in the description and in the claims as ‘cracking’.

According to an illustrative embodiment, there is provided a method comprising:

providing at least one flexible mold that is at least partially filled with dried wet-cast concrete products; each of the at least one flexible mold having a peripheral edge; and

removing a vacuum on the at least one flexible mold by moving at least one portion of the peripheral edge away from another portion of the flexible mold that is adjacent to the at least one portion of the peripheral edge.

According to another illustrative embodiment, there is provided a system for cracking at least one flexible mold of dried wet-cast concrete products, the system comprising:a table defining a surface for receiving the at least one flexible mold thereon; andat least one mold-bending member that is mounted to the table so as to be movable towards and away a mold-contacting position that forces an edge portion of the at least one flexible mold to move away from the surface.

According to still another embodiment, there is provided a system for cracking at least one flexible mold of dried wet-cast concrete products, the system comprising:a table defining a surface for receiving the at least one flexible mold thereon;at least one mold-bending member that is mounted to the table under the surface so as to be movable towards and away a mold-contacting position that forces an edge portion of the at least one flexible mold to move away from the surface; the table including at least one opening, each registered with a corresponding one of the at least one mold-bending member; the at least one mold-bending member extending at least partially out of the at least one opening when the at least one mold-bending member is in the mold-contacting position; andat least one mold-support member mounted to the table for movement between a first position away the surface and a second position adjacent the surface that maintains onto the surface a portion of the at least one flexible mold that is adjacent the edge portion when the at least one mold-bending member is in the mold-contacting position.

Other objects, advantages and features of embodiments of a method and system for cracking a flexible mold of dried wet-cast concrete products will become more apparent upon reading the following non-restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.

DETAILED DESCRIPTION

In the following description, similar features in the drawings have been given similar reference numerals, and in order not to weigh down the figures, some elements are not referred to in some figures if they were already identified in a precedent figure.

A system10for cracking flexible molds12of dried wet-cast concrete products14according to an illustrative embodiment will now be described with reference toFIGS.1,2and3A-3B. As can be seen inFIG.1, the system10is configured to simultaneously crack two (2) molds12at the same time. As can become more apparent upon reading the following description, the system10can be adapted to simultaneously receive and crack any number of molds12.

One of the molds12, prior to demolding, and therefore with dried wet-cast products14therein, is shown inFIG.4.

The mold is made of rubber, polyurethane, or of another flexible material.

While the illustrated products are in the form of five (5) identical elongated bricks14, the system10can be used for cracking a flexible mold including a various number of identical or of differently shaped products.

The system10is integrated to a conveyor16for the molds12.

The conveyor16is a pusher bar conveyor that comprises a table defined by two elongated side plates18joined by a series of parallel transversal shafts20, two pairs of legs22, each secured to a respective plate18near the longitudinal ends24and26thereof, and a conveying surface, defined on a first third of the table by a series of parallel longitudinal frame elements28-30and by a rectangular support plate32that extends through the remaining surface of the table.

The conveyor16further comprises a product-conveying mechanism including pusher bars34that are mounted to the table for movement along a closed loop path around the table that passes in close proximity to the conveying surface.

The product-conveying mechanism includes i) two strands of roller chains36(shown schematically inFIG.2by dashed lines), each one mounted on a respective plate18, on the inner side thereof, in a close loop fashion via a series of pulleys38, ii) a drive shaft40mounted to both plates18therebetween and a iii) motor42operatively coupled to the drive shaft40. Each roller chain36is coupled to the drive shaft40via a driving pulley44.

The pusher bars34are secured to both strands of roller chains36therebetween via mounting brackets46.

The table, the conveying surface and the product-conveying mechanism are not limited to the illustrated embodiment, and can be adapted, for example, to the configuration of the mold12. Since pusher-bar conveyors are believed to be well-known in the art, the conveyor16will not be described herein in more detail.

According to another embodiment (not shown), the system10is integrated to another type of conveyor, such as, without limitations, a belt conveyor.

In addition to the table of the conveyor16, the system10for cracking flexible molds12comprises a pair of support members48that maintain molds12unto the support plate32and a corresponding pair of mold-bending elements50that move both longitudinal edges52of the molds12away from the plate32while the molds12are maintained thereon.

Two independent pairs of a mold-bending element50with a corresponding support member48are provided and positioned on the conveyor16so as to independently and simultaneously bend both longitudinal edges52of the molds12. According to another embodiment, a single pair of mold-bending element50and support member48is provided that cracks the molds12by bending their longitudinal edges52in consecutive passes therethrough or by bending a single one of the longitudinal edges52, depending for example on the configuration and size of the molds12and/or of the products14therein.

Both the support member48and mold-bending element50are secured to the conveyor16via a pair of opposite mounting assemblies54that is secured to a respective side plate18. Each mounting assembly54includes a shelf56secured to a respective plate18via triangular-shaped brackets58so as to extends laterally from the plate18, and a vertical member60mounted to the shelf so as to extend upwardly therefrom.

The support member48is in the form of a cylindrical rod that is mounted to the vertical member60for pivotal movement about pivotal axis64via an actuating assembly62. The axis64is parallel to both the plate32and the edges52of the molds12that are moved face down by the conveyor16.

The actuating assembly62includes i) a cylindrical rod66that is pivotably mounted via rollers68to both vertical members60therebetween and ii) two (2) first levers70secured to the cylindrical rod66, each near a respective longitudinal end72thereof. The support member48is mounted to both levers70therebetween, near the end thereof opposite the ends receiving the cylindrical rod66, so as to be generally parallel to the rod66.

The longitudinal ends of both rods48and66are operatively coupled to a cylinder actuator74via a second lever76. The lever76is secured at one end to the rod66and at the other end to the cylinder74. A bridge plate78further attached both levers70and76for solidary pivotal movement therebetween and so to add rigidity to the assembly.

A mechanical stop (not shown) can be provided to limit the movement of the support member48, such as on the cylinder74to limit its stroke.

Turning now toFIGS.3A-3B, the mold bending elements50are in the form of blades that are mounted to the actuating assemblies62for pivoting movement towards and away a mold-contacting position. Each of the four blades50is registered with a corresponding opening80in the plate32and has a length comparable, but slightly smaller, thereto so as to be movable in and out thereof. The openings80are positioned parallel to the axis64and are located so as to be registered with the longitudinal edges52of the molds12.

The member82comprises a first arm83that is pivotably mounted to two laterally opposite vertical member60via a rod84that is pivotably mounted thereto via rollers68.

The L-shaped member82further includes a second arm85that is fixedly mounted to the first arm83using fasteners86so as to extend generally perpendicularly therefrom. For that purpose, the first arm83includes a pair of parallel slots88to receive the fasteners86therein and to further allow adjusting the longitudinal position and/or angle of the second arm85relative to the first arm83.

According to another embodiment (not shown), the second arm85is secured to the first arm83so that their relative positions cannot be adjusted. According to still another embodiment, the second arm85is integral to the first arm83. According to a further embodiment, another member than an L-shaped member is used to pivotably mount the blade50to the table of the conveyor16.

Each pair of transversally aligned blades50are mounted to a corresponding pair of laterally opposite second arms50therebetween via a rectangular rod90that is secured thereto.

The L-shaped member82is mounted, at the intersection of both arms83and85, to the end of the cylinder74opposite the second lever76.

As will now become apparent to a person skilled in the art, the actuation of the cylinder74causes the simultaneous i) pivoting of the L-shaped member82so that the blades50are moved upwardly through the openings80and ii) movement of the support members48towards the plate32so as to maintain molds12thereon in close contact with the plate32. It results from such movements that the longitudinal edges52of the molds12are moved upwardly away from the plate32, while portions of the molds12that are longitudinally adjacent to the edges52are maintained onto the plate32. This removes vacuum between the molds12and products14and therefore the adherence therebetween, thereby facilitating the removal of the products14during demolding.

The actuation of the cylinder74is synchronized with the passage of the molds12along the conveyor16, the position of the molds12being indexed by the pusher bars34. Depending on the products14or on the configuration of the molds12, the system10can be operated so that the molds12are cracked while moving onto the conveyor16or while their movements are stopped.

According to another embodiment, the position of the molds12on the conveyor16is indexed using sensors (not shown) or switches (not shown).

It is to be noted that connectors, cables, and other secondary or non-mechanical components of the system10have been omitted in the figures so as to alleviate the views.

The operation of the system10is summarized inFIG.5.

It is to be noted that many modifications could be made to the method and system for cracking a flexible mold described hereinabove, for example:the method and system are not limited to cracking molds12at their longitudinal side edge; the system can be modified, including the orientation of the blades50and openings80, so that the molds12are cracked alternatively or complementarily at their lateral sides;the blades50can be substituted with a plurality of fingers or plungers (not shown) and the elongated openings80can be replaced by a series of holes (not shown) in the plate32;the support members48can take other form or be omitted. For example, the support member can be rectangular, triangular, L-shaped, etc.instead of members that pushes the edges52of the molds12upwardly, the mold-bending mechanism can be configured to move the edges52downwardly. For example, the mold-bending mechanism can be in the form of one or more grabbing members (not shown) that pull the edges52of the molds12downwardly while the edges52are positioned above an opening in the conveying surface;according to still another embodiment, the vacuum is removed by stretching the mold12longitudinally or laterally;the mold-bending mechanism can be adapted to bend the molds12while they are face up on the table;the mounting assemblies54are not limited to the illustrated embodiment and can take other forms allowing to secure both the support member48and mold-bending element50to the conveyor16;the system10can be modified so as to include a different actuator for the mold-bending mechanism and support member48than the cylinder74. Also, according to another embodiment, a different actuator is provided for each mold-bending mechanism and each support member;while the support members48are movable between deployed and retracted positions, they can be modified so as to be fixedly mounted to the conveyor16.

Although a method and system for cracking a flexible mold of dried concrete products have been described hereinabove by way of illustrated embodiments thereof, they can be modified. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that the scope of the claims should not be limited by the preferred embodiment but should be given the broadest interpretation consistent with the description as a whole.