Vacuum vibration press for forming engineered composite stone slabs
View Patent ↗A vacuum vibration press manufactures engineered stone slabs that are equal or superior in appearance and physical properties to slabs manufactured using a conventional Breton press, while weighing less, costing less to manufacture, providing shorter press cycle times, requiring less resin, and consuming less energy. In addition to providing a vibration device above the slab, the press also includes a second vibration device below the slab, which replaces the massive inertial base of a Breton press. The vibration devices can have different frequencies, amplitudes, and/or vibration axes. The press can be completely enclosed within a vacuum chamber, and vibrationally isolated from surrounding structures. In embodiments, volume reduction blocks reduce the volume to be evacuated. Embodiments use screw jacks and springs or air bags to provide controlled pressing force and precisely uniform slab thickness. Slabs can be inserted and removed on a conveyor belt, or in separate trays on rollers.
1. A lightweight, energy efficient, low cost vacuum vibration press for forming engineered stone slabs by simultaneously compressing and vibrating under vacuum a slab mixture, the press comprising:
a vacuum chamber;
a vibration table having a planar surface configured to support the slab mixture, said vibration table being located within the vacuum chamber;
a pressing mechanism that is configured to compress the slab mixture between the pressing mechanism and the vibration table, said pressing mechanism being located within the vacuum chamber;
a first vibration device attached to a bottom of the vibration table; and
a second vibration device attached to a top of the pressing mechanism;
the pressing mechanism and the vibration devices being configured to apply at least 8 psi of compressional force and at least 0.6 kw per square foot of vibrational force to the slab mixture to force the stone granules in a slab mixture having between 88% and 94% stone granules and stone powder, and between 6% and 12% resin into a configuration in which the resin and stone powder fill substantially all voids between the stone granules.
2. The press of claim 1 , wherein forcing the stone granules of a 45 square foot slab mixture into a close-packed configuration requires application to the slab mixture of no more than 25 HP of combined input vibrational energy by the vibration devices attached to the bottom of the vibration table and the top of the pressing mechanism.
3. The press of claim 1 , wherein forcing the stone granules into a close-packed configuration requires the pressing mechanism to able to apply no more than 10 psi of pressure to the slab mixture.
4. The press of claim 1 , wherein the press is able to apply sufficient compressional and vibrational forces to the slab mixture to reduce its volume by at least 10% compared to its volume before the application of the compressional and vibrational forces.
5. The press of claim 1 , wherein the first vibration device and the second vibration device are synchronous in frequency and phase.
6. The press of claim 1 , wherein the vibration devices can apply vibration frequencies from 100 Hz up to 100,000 Hz by applying at least one of mechanical and ultrasonic energy, and where the vibration amplitude is between 0.001 mm and 2 mm.
7. The press of claim 1 , wherein at least one of the vibration devices is driven by a force that is at least one of pneumatic, electrical, magnetic, and hydraulic.
8. The press of claim 1 , further comprising a transport mechanism for transporting the slab mixture onto and off of the vibration table.
9. The press of claim 8 , wherein the transport mechanism includes a conveyor belt.
10. The press of claim 9 , wherein 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.
11. The press of claim 10 , wherein the conveyor belt is wider than the vacuum chamber, and the seal is formed between the upper and lower sections and the conveyor belt.
12. The press of claim 1 , further comprising 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.
13. The press of claim 1 , further comprising 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.
14. The press of claim 13 , wherein the space-adjusting mechanism includes a screw jack.
15. The press of claim 1 , wherein the pressing device includes at least one of an air bag, an air cylinder, and a spring.
16. The press of claim 1 , wherein the first vibration device and the second vibration device are synchronous in frequency and 180° out of phase.
17. The press of claim 1 , wherein the first vibration device and the second vibration device are synchronous in frequency and 90° out of phase.
18. The press of claim 1 , wherein the first vibration device and the second vibration device are synchronous in frequency and out of phase by an angle that is neither 180° nor 90°.
19. The press of claim 1 , wherein the first vibration device and the second vibration device vibrate at different frequencies.
20. The press of claim 1 , wherein the first vibration device and the second vibration device vibrate at different amplitudes.
21. The press of claim 1 , wherein a vibration axis of the first vibration device is parallel to a vibration axis of the second vibration device.
22. The press of claim 1 , wherein a vibration axis of the first vibration device is perpendicular to a vibration axis of the second vibration device.
23. The press of claim 1 , wherein a vibration axis of the first vibration device is neither parallel nor perpendicular to a vibration axis of the second vibration device.
24. The press of claim 1 , wherein at least one of a vibration axis of the first vibration device and a vibration axis of the second vibration device is parallel to the planar surface of the vibration table.
25. The press of claim 1 , wherein at least one of a vibration axis of the first vibration device and a vibration axis of the second vibration device is not parallel to the planar surface of the vibration table.
26. The press of claim 1 , wherein the first and second vibration devices are linear vibration devices, and a vibration axis of the first vibration device is normal to the planar surface of the vibration table, while a vibration axis of the second vibration device is parallel to the planar surface of the vibration table.
27. The press of claim 1 , where at least one of the vibration devices is a rotary vibration device.
28. The press of claim 1 , wherein a plurality of vibration devices is attached to at least one of the pressing mechanism and the vibration table.
29. The press of claim 1 , wherein at least one of the vibration devices is able to apply mechanical vibrations.
30. The press of claim 1 , wherein at least one of the vibration devices is able to apply ultrasonic vibrations.