Vibration table with circular mounting surface

#Not Applicable

#Vibration tables are used primarily in connection with test fixtures designed to test products under vibrating conditions. The general construction of vibration tables is well known. Generally they include upper and lower plates separated by spacers, with a vibrator mounted on the bottom of the lower plate and a test product mounted on the top of the upper plate. Representative vibration tables are shown in Applicant's U.S. Pat. No. 5,594,177 (which is incorporated by reference) and U.S. Pat. No. 5,402,991.

#An object in the design of a vibration table is to provide a table that transmits a high proportion of the vibration energy to the test product over a desired frequency range. In order to accomplish these goals, it is generally desirable to make the table as rigid as possible and yet as light as possible. Rigidity maximizes higher frequency and higher energy transmission and minimizes resonant frequencies at low frequency ranges, while a light weight table minimizes energy loss that results from the mass of a heavy table. To accomplish these goals, tables are frequently made with a hollow or semi-hollow core. In Applicant's U.S. Pat. No. 5,594,177, the table includes spaced upper and lower plates connected together at the periphery by edge spacers and having intermediate spacers interconnecting the plates at intermediate positions.

#FIG. 1 is a perspective view of the improved vibration table with circular mounting surface of the present invention.

#FIG. 1A is a perspective view of a vibration table having a squared surface and an insulating layer.

#FIG. 2 is a fragmentary side elevational view taken along line 2-2 of FIG. 1A, showing the spacer mounted in a shaker table and with a test product mounted thereon.

#Referring now to the drawings, a shaker table 10 constructed in accordance with the present invention is shown in FIG. 1. Shaker table 10 includes an aluminum upper plate 12 (typically about one-half inch thick), lower plate 14, and edge spacers 16 separating the upper and lower plates. A center support 17 (FIG. 10) is secured in the center of the table surface between the upper and lower plates. Edge spacers 16 are attached to the upper and lower plates by bolts 18 and typically space the plates about one-half inch apart. Bolts 18 typically are ⅜ inch internal hex head stainless steel bolts that extend all the way through the upper and lower plates and edge spacers and are secured by nuts 19 on the lower ends. Lock washers are positioned adjacent the heads. These bolts are tightened to a torque of about 30-45 ft lbs for desired rigidity. The higher torque limit is determined by the bolt strength. The lower limit is significant for energy transmission. The G forces transmitted by the table drop off significantly when a lower torque setting is used.

#In one embodiment, shown in FIG. 1A, the vibration table 10′ includes an insulating sheet or layer 20, preferably a ceramic material, is bonded on the top of upper plate 12′. A metal top plate formed of titanium or the like can be positioned on the top of the insulating sheet but is not essential in the present invention. An insulating sheet is generally employed, but there are some applications where an insulating sheet is not used. The table of FIG. 1A is illustrated as square, but the modification is applicable to the round table 10 of the present invention.

#The insulating sheet and upper surface of plate 12 include a plurality of openings 36 and 24, respectively, spaced in a conventional pattern (typically a rectangular grid on four inch or 100 mm centers) over the top of the vibrator table. The openings in the upper plate are internally threaded. These openings are larger than in a conventional vibration table to accommodate novel inserts 26 of the present invention.