COMPOSITE STONE SLABS

RELATED APPLICATIONS

[0001 ] This application claims the benefit of U.S. Provisional Application No. 61/526,308, filed August 23 , 201 1 , which is herein incorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

[0002] The invention relates to composite stone slabs, and more particularly, to vibrating press apparatus for making composite stone slabs

BACKGROUND OF THE INVENTION

[0003] Manufactured composite stone slabs and tiles, which are sometimes referred to herein generically as "quartz slabs," have been produced since the mid 1980's. They typically include 90-93% stone content, with the remaining 7- 10% being resin, pigment, and additives, which are sometimes generically referred to herein as "binder." The most commonly used method of producing manufactured stone slabs is generally referred to as the "Breton" method, or "Bretonstone," because the main supplier of the equipment that is used to make composite stone slabs is Breton Spa of Italy. In particular, the Breton Vacuum Vibration Press and copies thereof play a key role in the production of such stone slabs.

[0004] Figure 1 illustrates the basic steps used to manufacture stone slabs using the Breton method. First, the raw materials are prepared 100. Typically, this includes preparing a mixture containing about 65% stone granules 102 such as crushed quartz, granite, mirror, and/or glass in granule sizes from 0.2 mm up to 6mm or even 15mm. About 25 % "quartz powder" 104 is also included, where the term "quartz powder" generically refers to one or more powdered minerals such as silica and/or quartz, typically in an approximately minus 325 mesh (minus 45 micron) size. Finally, about 7 to 10% resin 106 is included, typically with additives such as catalyst 108, pigment blends 1 10, and dispersing media.

[0005] After the raw materials are weighed and measured, they are

transported to a mixer 1 12 and mixed together 1 14. Typically, the mixer is charged with the stone granules, and then the resin and pigments are added and the combination is mixed until the particles and granules are fully wetted. For purposes of color design, two, three, or more mixers may be employed, each with a different color of raw materials and pigments. This is illustrated in Figure 2.

[0006] The quartz powder is then added while the mixing continues. When combined with the resin, the quartz powder forms a paste which serves as the binder between the stone granules. The mixed materials are then formed into a single slab 1 16, either in a rubber mold, a metal mold, or on a sheet of paper or other suitable carrier which can be used to transport the formed slab into the vacuum vibration press.

[0007] Once it has been transferred to the press, the formed slab is simultaneously evacuated, vibrated, and pressed 1 18 so as to compact the mixed material, remove air from the mixture so that there will be no voids in the finished slab, and make it flat. The mode and time of pressing also assist in creating the desired blending of the various materials and colors in the slab. The degree and intensity of the mixing, blending, and vibrating will all affect the color(s) and look(s) of the finished slab. An example of the parameters used in the pressing step 1 18 might be to:

• evacuate down to a pressure of 1 - 100 torr;

• apply the press plate with a downward force of 0.01 to 300 psi;

• apply vibration having a frequency of about 1000-5000 rpm and an

amplitude of 0.05 to 2 mm; and

• continue the above for between 20-280 seconds to produce a pressed, void- free slab. [0008] Once the slab has been pressed, it is transported to an oven or to some other location for curing 120. Depending upon the adhesive (resin) used to bind the particles together into the slab, the curing and hardening process can take place at ambient temperature or at an elevated temperature, and can require from a few minutes up to many hours. After curing and hardening, the slab is returned to room temperature (if heat has been applied).

[0009] The cured slab is then ground and polished 122 to a desired thickness and finish, using technology similar to what is used to grind, calibrate, and then polish conventional natural granite stone slabs. The final result 124 is a finished quartz slab, also referred to as an engineered stone slab, a composite stone slab, a manmade stone slab, and other, similar expressions.

[0010] While the Breton press and the Breton process are effective, there are several disadvantages associated with the Breton style of pressing equipment and procedure, and with similar equipment and procedures marketed by other manufacturers. With reference to Figure 3, the Breton press 300 includes a press cover/vacuum chamber 302 which is also the housing for vibrating motors 304 mounted to a vibration plate 306 and suspended by air bags 308 or similar vibration mounts. The press cover 302 is mounted on pneumatic posts 3 10 so that it can be lowered onto a formed slab 3 12 which is typically brought into the press on a conveyer belt 3 14 running between the press cover and a press base 3 16. The Breton press 300 employs massive weight and power to simultaneously apply a vacuum, vibration, and downward pressure to the formed slab 3 12. The press cover 302 and included mechanisms 304, 306, 308 weigh about 15,000 pounds, and the press base 3 16 weighs about 30,000 pounds. Altogether, the Breton press 300 typically weighs from 50,000 to 75,000 pounds. In addition, it must be anchored to a vibration-damped block 3 18 of concrete that is set beneath the concrete floor 320 and surrounded by a vibration isolating material 322. The block 3 18 is approximately 20'long by 15' wide by 15' deep and weighs another 100-300 tons.

[0011] Also, the steel vacuum chamber/press cover (302), which is typically shaped as a rectangular box, is massively built to withstand the vacuum force and the destructive long term effects of the vibration. [0012] In addition, because the formed slab 3 12 is positioned on a solid base 3 16 that is bolted to a concrete block 3 18, which by itself weighs 30,000 to 40,000 pounds, an enormous vibration force (about 100 to 300 hp at 1000 to 5000 rpm) must be applied so as to properly vibrate the slab. Essentially, to press and vibrate a quartz slab 3 12 weighing 400- 1500 pounds, the Breton press 300 is required to vibrate a mechanism 302, 3 16 weighing 50,000 to 75,000 pounds, plus the concrete block 3 18 it is bolted to. In addition, the press plate 306 that compresses the slab and the mount 308 for the vibrating motors are similarly massive.

[0013] Also, the vacuum vibration cycle time per slab for the Breton press 300 is about 70-200 seconds, which is time consuming, and the Breton-made press 300 costs about $6 to $7 million US dollars, which is very expensive.

[0014] What is needed, therefore, is a vacuum vibrating press which can apply vacuum, vibration, and pressure in amounts similar to a Breton press but with significantly lower cost of manufacture and vibrational energy

requirements, and with shorter pressing times.

SUMMARY OF THE INVENTION

[0015] A vacuum vibration press for making composite stone slabs applies as much or more vibration and pressure to a formed quartz slab as a conventional Breton press, while weighing less, costing less to manufacture, providing shorter press cycle times, and requiring less energy consumption to vibrate the slab as compared to a Breton press. It is estimated that the press of the present invention can be manufactured at a cost of approximately $750,000 US dollars.

[0016] In embodiments, instead of a rectangular vacuum chamber with enormous strength and weight, the press of the present invention uses a light weight cylindrical chamber inside of which a vibration mechanism and slab support are suspended. In contrast to the traditional Breton press, the vacuum chamber of the present invention is not vibrated, but is actually isolated from all vibration. This approach makes it feasible to use any type of design and/or construction for the vacuum chamber, including lightweight cylindrical designs, and also rectangular and massive designs if so desired.

[0017] Instead of vibrating a 50,000-75,000 pound press and its 100+ ton base concrete block (requiring 100-300 hp), the press of the present invention is only required to vibrate about 3000 to 5000 pounds of machinery and slab, which requires only about 15 to 25 hp.

[0018] The portion of the press that is vibrated is referred to herein as the Vibration and Pressing Mechanism (VPM). The VPM is simple and light, comprising a Vibration Press Table Support Frame, or VPT-SF, a vibration table, a press plate and pressing mechanism, and one or more Vibration Devices (VD' s).

[0019] The Vibration Press Table Support Frame (VPT-SF) is clamped or bolted to the inside of the vacuum chamber. The vibration table is connected to and raised up from the support frame with air springs, bags or another suitable mechanism which allows the vibration table to move freely without transmitting excessive vibration to the support frame or to the vacuum chamber. The press plate and pressing mechanism are supported above the formed slab, and are lowered, positioned precisely, and vibrated so as to accomplish the required compaction of the slab material components. The Vibration Devices (VD' s) are mounted to the bottom of the press table and/or to the top of the press plate, and cause the quartz slab and the entire vibration press mechanism to vibrate, but do not cause the vacuum chamber to vibrate appreciably.

Definitions of terms

[0020] Note that the following terms are used with the indicated definitions throughout this paper.

[0021] Quartz Slabs: This term refers generically to manmade composite stone slabs. Other terms which are used synonymously and interchangeably include: engineered stone slabs; agglomerated stone slabs; quartz slabs; composite stone or quartz slabs; manmade stone slabs; and agglomerated stone slabs.

[0022] Stone Granules (SG): This term refers generically to particles of stone (frequently quartz or silica based stone) or of other hard materials such as glass, granite, marble, and such like, having sizes in the range from about 200 microns up to 2-3 centimeters. The term is used interchangeably herein with the terms aggregates and granules.

[0023] Quartz Powder (QP): This term refers to powdered material ranging in size from about lmicron to about 300 microns. In the industry, the QP is commonly finely crushed and/or milled quartz or silica sand. The term is used interchangeably herein with the terms silica powder, quartz powder, and filler. It is readily available worldwide in a generally standard minus 325 mesh size, and can be made from marble (calcium carbonates), glass, granite, or any other material that can be powdered and used for making quartz slabs.

[0024] Resin: in the quartz slab industry the resin is, for economic reasons, typically a modified polyester thermosetting resin. The term resin is used throughout this paper to refer to any resin and/or adhesive system capable of adhering together the range of stone granules and quartz powder pieces that are used to form a quartz slab. Examples include epoxy, urethane, acrylic, vinyl ester, silicone resins, and even cementitious adhesives based on the various forms of hydraulic type cements. When the resin is a polyester material, then it may include various additives that affect the cure rate and especially the adhesion of the resin to silica and/or quartz based minerals and granites.

[0025] Press: This term is used herein to refer to any machine or device that can simultaneously apply a vacuum, a downward mechanical pressing, and vibration to a quartz slab during the production process. The term is used interchangeably herein with the terms vacuum vibration press and VVP.

[0026] Pressing: This term is used herein to refer to the process of simultaneously applying vacuum, downward pressure, and vibration at selected levels and intensities. [0027] The present invention is a lightweight, energy efficient, low cost vacuum vibration press for forming composite stone slabs by simultaneously compressing and vibrating the slabs under vacuum. The press includes a vacuum chamber, a vibration table support frame fixed within the vacuum chamber, a vibration isolation system fixed to the vibration table support frame, a vibration table supported by the vibration isolation system, the vibration isolation system providing at least a partial vibration isolation between the vibration table support frame and the vibration table, a pressing mechanism that is configured to compress a slab mixture between the pressing mechanism and the vibration table at a pressure of between 1 and 100 psi, and at least one vibration device configured to vibrate at least one of the vibration table and the pressing mechanism. The vacuum chamber is configured so that it surrounds and encloses within its vacuum space the vibration table support frame, the vibration isolation system, the vibration table, the slab mixture, and the pressing mechanism.

[0028] Embodiments further include at least one vacuum pump suitable for evacuating the vacuum chamber.

[0029] Some embodiments further include a transport mechanism for transporting the slab mixture onto and off of the vibration table. In some of these embodiments, the transport mechanism includes a conveyor belt. In some of these embodiments, the vacuum chamber includes an upper section and a lower section, the upper and lower sections being separable to allow the conveyor belt to pass between the upper and lower sections so as to bring a slab mixture to the vibration table and remove a pressed slab from the vibration table, the upper and lower sections being sealable so as to form a seal that enables evacuation of the chamber during pressing of the slab mixture. And in some of these embodiments, the conveyor belt is wider than the vacuum chamber, and the seal is formed between the upper and lower sections and the conveyor belt.

[0030] In various embodiments the vibration isolation mechanism includes at least one of air bags and springs. [0031] Some embodiments further include at least one vacuum volume reduction block within the vacuum chamber, the vacuum volume reduction block being configured to fill space within the vacuum chamber so as to reduce an evacuation volume that is subject to evacuation during pressing of the slab mixture.

[0032] Other embodiments further include at least one space-adjusting mechanism that is configured to enable precise adjustment of a spacing between the pressing mechanism and a slab mixture supported by the vibration table, said precise adjustment resulting in a pressed composite stone slab having a uniform thickness across its length and width. In some of these embodiments the space adjusting mechanism includes a screw jack. In some of these embodiments the screw jack is assisted by a pressing device in creating a downward pressure on the pressing mechanism. And in some of these embodiments the pressing device includes at least one of an air bag, an air cylinder, and a spring.

[0033] In certain embodiments the vibration device is able to apply vibration to the vibration table at a frequency between 100 rpm and 5000 rpm, and at an amplitude between 0.001 and 3mm length. And in some of these embodiments the vibration device is driven by a force that is at least one of pneumatic, electrical, magnetic, and hydraulic.

[0034] In various embodiments the vibration device includes an ultrasonic transducer that is able to apply vibration to at least one of the vibration table and the pressing mechanism at a frequency between 1000 Hz and 5 MHz. And in some of these embodiments the vibration device is able to apply both mechanical vibrations and ultrasonic vibrations to at least one of the vibration table and the pressing mechanism.

[0035] In certain embodiments the vibration device is able to apply vibration with respect to a plane of the slab mixture in a vibration mode and direction that is at least one of one of vertical and linear, vertical and circular, horizontal and linear, and horizontal and circular. [0036] In embodiments a plurality of vibration devices is attached to one of the vibration table and the pressing mechanism, the vibration devices being synchronized in frequency, phase, and amplitude so as to apply vibration at a common frequency and phase and a uniform amplitude over the slab mixture. In some of these embodiments a first plurality vibration devices is attached to the vibration table, and a second plurality of vibration devices is attached to the pressing mechanism. In some of these embodiments the first plurality and the second plurality are synchronous in frequency and phase. In other of these embodiments the first plurality and the second plurality are synchronous in frequency and 180° out of phase. In still other of these embodiments the first plurality and the second plurality are synchronous in frequency and 90° out of phase. In yet other of these embodiments the first plurality and the second plurality are synchronous in frequency and out of phase by an angle that is not 180° and is not 90°. In still other of these embodiments the first plurality and the second plurality vibrate at different frequencies. In yet other of these embodiments the first plurality and the second plurality vibrate at different amplitudes. In still other of these embodiments at least one of the first plurality and the second plurality is able to apply mechanical vibrations. And in yet other of these embodiments at least one of the first plurality and the second plurality is able to apply ultrasonic vibrations.

[0037] The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure l is a flow diagram illustrating the overall production process for making composite stone slabs according to the traditional Breton process of the prior art; [0039] Figure 2 is a flow diagram illustrating the mixing and combining of a plurality of powder, stone particles, and other components having different colors and/or other differing properties, according to the traditional Breton process of the prior art;

[0040] Figure 3 is a cross-sectional illustration of a traditional Breton press of the prior art;

[0041] Figure 4A is a side view of a vacuum chamber in an embodiment of the present invention that includes hinged doors on its ends;

[0042] Figure 4B is an end view of the vacuum chamber of Figure 4A;

[0043] Figure 5A is a top view of a split vacuum chamber in an embodiment of the present invention showing a conveyor belt wider than the vacuum chamber and passing between the split sections of the vacuum chamber;

[0044] Figure 5B is a side view of the split vacuum chamber of Figure 5A;

[0045] Figure 6A is a cross-sectional end view of an embodiment of the present invention showing the press mechanism within the vacuum chamber;

[0046] Figure 6B is a cross-sectional view of the embodiment of Figure 6A;

[0047] Figure 6C is a close-up cross-sectional view of the embodiment of Figure 6B showing a support mechanism suspending the press table above the press support frame;

[0048] Figure 6D is a top view of the press plate of Figure 6A illustrating support of the press plate by a plurality of screw jacks;

[0049] Figure 6E is a side view of the press plate of Figure 6D;

[0050] Figure 6F is a close-up cross-sectional view of a screw jack and air bag supporting a press plate in an embodiment similar to the embodiment of Figure 6A; [0051] Figure 7 is a cross-sectional end view of the embodiment of Figure 6A showing only the vacuum volume reduction blocks within the vacuum chamber;

[0052] Figure 8A is a cross-sectional side view showing composite slabs being delivered to and removed from a vacuum chamber of an embodiment by a conveyor belt; and

[0053] Figure 8B is a cross-sectional side view showing composite slabs being delivered to and removed from a vacuum chamber of an embodiment in separate trays on rollers.

DETAILED DESCRIPTION

[0054] The present invention is a vacuum vibration press for making composite stone slabs, wherein the pressing and vibrating mechanisms are contained within the vacuum chamber, so that there is no need for a massively reinforced vacuum chamber and no need to vibrate the vacuum chamber together with the formed slab. The invention applies as much or more vibration and pressure to a formed quartz slab as a conventional Breton press, while weighing less, costing less to manufacture, providing shorter press cycle times, and requiring less energy consumption to vibrate the slab as compared to a Breton press.

[0055] With reference to Figures 4A and 4B (side and end views,

respectively), instead of a rectangular vacuum chamber with enormous strength and weight, the present invention uses, in embodiments, a light weight cylindrical chamber 400 inside of which the vibration mechanism and slab support are suspended. In the embodiment of Figures 4A and 4B, the vacuum chamber includes a cylindrical section 402 terminated at one end by an end cap 404 that is bolted 406 in place and at the other end by an end cap 408 that is hinged 410 and held in place by clamps 412 attached to a flange 414. Both end caps 404, 408 include hinged doors 416 through which a formed slab 3 12 can be inserted into the press. Because the vacuum chamber itself 400 is not vibrated, in contrast with the traditional Breton type press 300, and is actually isolated from all vibration, virtually any type of design or construction for the vacuum chamber 400 can be used, even a rectangular and massive chamber if so desired.

[0056] Figures 5A and 5B are top and side views, respectively, of an embodiment that includes a horizontally split vacuum chamber 500 which forms a vacuum seal between the vacuum chamber 500 and a conveyor belt 3 14, the conveyor belt being wider than the vacuum chamber 500 itself. The conveyor belt 3 14 passes between an upper flange 502 and a lower flange 504 of the vacuum chamber 500 so as to convey a formed slab 3 12 between an upper half of the vacuum chamber 506 and a lower half of the vacuum chamber 508.

[0057] With reference to Figures 6A and 6B, instead of vibrating a 50,000- 75,000 pound press 302, 3 16 and its 100+ ton base concrete block 3 18

(requiring 100-300 hp), the press 400 of the present invention is only required to vibrate about 3000 to 5000 pounds of machinery and slab, referred to herein as the Vibration and Pressing Mechanism or VPM, which requires only about 15 to 25 hp. The VPM is relatively simple and light, and includes the following elements.

[0058] A Vibration Press Table Support Frame- (VPT-SF) 600 is clamped or bolted by tank support brackets 602 to the inside of the vacuum chamber 408, which is cylindrical in the embodiment of Figures 6A and 6B. The VPT-SF 600 can be accessed inside the chamber 408 by removing the Vacuum Volume Reduction Blocks (VVRB) 604, or by unclamping, unbolting, and sliding it out of the chamber through the hinged tank head end cap (416 of Figures 4A and 4B). In similar embodiments, the VPT-SF can be slid or rolled out from inside the chamber for maintenance purposes, which greatly reduces maintenance times.

[0059] A vibrating table 604 is connected and suspended above the support frame 600 by air springs and/or bags 606 with appropriate height restraint and leveling devices (628 in Figure 6C) to maintain levelness and proper working height. In the embodiment of Figure 6C, the leveling device includes a metal rod or chain 628 and a height adjusting mechanism 610. In other embodiments, instead of air springs and bags, mechanical springs or another suitable mechanism is used which allows the vibration table 604 to move freely enough for the vibration mode selected and without transmitting excessive vibration to the support frame 600 and vacuum chamber 408.

[0060] A press plate 612 and pressing mechanism 614 are supported above the formed slab 3 12 and are lowered, positioned precisely, and vibrated to accomplish the required compaction of the slab material components.

[0061] The Vibration Devices (VD) 608, which can be either traditional mechanical vibration devices (driven by pneumatic, electrical, magnetic, hydraulic, or any other power source that creates mechanical vibration of frequency approximately 100-5000 rpm and amplitude of approximately 0.001 to 1 mm length) and/or ultrasonic transducers (frequency approximately 1000 - 5 MHz), are mounted to the bottom of the press table 604 and/or to the top of the press plate 612.

[0062] With respect to the plane of the slab 3 12 itself, the vibration mode can be vertical/linear, vertical/circular, horizontal/linear, horizontal/circular, or any combination thereof. The VD's cause the quartz slab 3 12 and the entire vibration press mechanism (only about 3000 - 5000 pounds of mechanism) to vibrate, but do not cause the vacuum chamber 400 to vibrate appreciably.

[0063] Depending on the dimensions of the slab to be pressed, in some embodiments a plurality of VD' s 608 are mounted either to the bottom of the press table 604 or to the top of the press plate 612, or both (as shown in Figure 6F). In these embodiments, the VD' s are synchronized electronically and/or mechanically so that all of the VD' s vibrate in phase with one another, both in amplitude and in frequency, causing the plurality of VD's to act as one large vibration device.

[0064] In embodiments where a first group of VD 's is attached to the bottom of the press table 604 and a second group of VD' s is attached to the top of the press plate 612, each group of VD's is synchronized to vibrate in phase both in amplitude and in frequency within the group. The two groups can be synchronized with each other in any of several ways, including

• phase and frequency synchronized, so that both the press table 604 and the press plate 612 rise and fall at same time;

• frequency synchronized in opposite phase, so that the press table 604 rises when the press plate 612 falls and vice-versa, thereby periodically and simultaneously "pressing" against the quartz slab 304;

• frequency synchronized and 90° out of phase, so that as the press plate 612 is going down, the press table 604 is moving laterally;

• frequency synchronized and with some other phase offset;

• frequency un-synchronized, i.e. the two groups operating at different frequencies;

• operating at different amplitudes, so that the vibration applied by the VD's of the first group to the press table is at a different amplitude from the vibration applied by the VD' s of the second group to the press plate; and

• any combination of the above.

[0065] Note that embodiments of the present invention apply both mechanical and/or ultrasonic vibrations using any of these combinations of VD' s and combinations of phase, frequency, and amplitude synchronization.

[0066] With reference to Figures 6D and 6E, embodiments of the present invention employ precision screw jacks 616 attached to press screw supports 618 to lower the press plate 612 and apply pressing force on the formed slab 3 12 during vibration. Figure 6D is a top view of a press plate 612 suspended by a plurality of screw jacks 616 attached to a plurality of press screw supports 618. Figure 6E is a side view of the press plate 612, screw jacks 616 and press screw supports 618 of Figure 6D. In embodiments, the screw jacks 616 can be controlled to lower the press plate 612 at a variable and defined rate of decent to a proper thickness position which will allow the slab material to move or migrate across the slab area, resulting in a very even thickness across the entire slab area. With reference to Figure 6F, the pressing force of the positioning screw jacks 616 can be augmented with the force of air springs, air bags 620, or other pneumatic or hydraulic pressing devices. In some embodiments, the pressing force is sensed and regulated, either by sensing the pressure in the air bags 620 or by another sensing method, and the positioning of the screw jacks 616 is controlled so as to maintain the press plate 612 parallel to the press table 604.

[0067] Because of this method of lowering and positioning the vibrating press plate 612, embodiments of the present invention allow slabs to be produced with less thickness variance from side to side or end to end then for traditional Breton presses 300, thereby reducing the average amount of material that must be used to produce a slab of given finished thickness after grinding. The traditional press technology suspends and lowers the press plate 306 with large air bags and/or air springs 308 and without precision screw jacks 616, and therefore the levelness and paralellness of the press plate 306 relative to the press base 3 16 on which the formed slab 3 12 rests, is determined only by the levelness of the distribution of the slab material 3 12 that has been spread in the slab forming process. Therefore, uneven spreading results in uneven slab thickness from end to end or side to side, which means that to maintain a given finished and post calibration slab thickness, the average formed slab thickness before grinding must be greater, and this increases the average amount of slab material (and therefore the cost) of the slab for any given final thickness.

[0068] In some embodiments, ultrasonic vibration is applied to the pressing plate 612, the vibration press table 600, 604, or both, which can substantially reduce the pressing cycle time. This is economically possible due to the light weight of the slab support 600, 604 and vibration mechanism 608.

[0069] In operating a traditional Breton press 300, a significant percentage of the pressing cycle time is devoted to evacuating the vacuum chamber to below 100 Torr (and in some cases even down as low as 1 -5 Torr). The volume of the vacuum chamber is a big factor in determining this time. This is one of the reasons for the choice of a low-volume rectangular vacuum chamber for the Breton machine, which of necessity requires massively thick and heavy walls to withstand the vacuum and the vibration. [0070] In embodiments of the present invention, the press uses a lightweight cylindrical vacuum chamber 402 which would normally have a huge interior volume and which would therefore require either massive vacuum pumps or long press cycle times to evacuate. This large chamber volume problem is eliminated by the use of vacuum volume reduction blocks VVRB 604. These are lightweight blocks 604 made from a material such as urethane or another foam, balsa wood, expanded cell plastic, metal, or any other suitable material, which can withstand the vacuum without distending or expanding, and which can effectively and substantially reduce the volume of the vacuum chamber 402 and thereby shorten the press cycle time. An end view showing the VVRB blocks 604 is presented in Figure 7. The vibration and pressing mechanisms have been omitted from Figure 7 for clarity of illustration.

[0071] With reference to Figures 8A and 8B, embodiments of the present invention are configured to accept formed slabs 3 12 and removed finished composite stone slabs 800 via any of several methods. These include slabs 3 12 carried on a continuous sheet of paper or metal on a conveyor belt 802, slabs 3 12 contained in rubber trays 804 carried on a conveyor belt 802, and slabs 3 12 located on individual trays or molds 804 of any appropriate material which arrive and depart on rollers 806 or on a conveyor belt 802.

[0072] The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.