Machine element or mechanism – Mechanical movements – Rotary to or from reciprocating or oscillating
Reexamination Certificate
1999-08-08
2001-11-27
Estremsky, Sherry (Department: 3682)
Machine element or mechanism
Mechanical movements
Rotary to or from reciprocating or oscillating
C074S087000, C425S456000
Reexamination Certificate
active
06321610
ABSTRACT:
BACKGROUND OF THE INVENTION
1. A Field of the Invention
The present invention relates, in general, to a vibration apparatuses and more particularly to a vibration apparatus for a variable amplitude type vibration table and which generates vertical vibration for the use of, for example, a concrete block molding machine.
2. Description of Prior Art
Many types of vibration apparatus have been known in the art which have vibration tables, vibration shafts having eccentric weights for vibrating the vibratory table. An example of such vibration apparatsu as described above is a vibration table for a concrete block molding machine which is disclosed in Japanese Patent Publication (unexamined) No. 2-80203 in which a material for concrete blocks is supplied into a mold form and a vibration table is provided for receiving the mold form. At a lower position of the vibration table, two vibration axial bodies of a dual axial structure having weights are provided so that the position of the weights can be directly changed by a hydraulic or an oil pressure device. In this conventional device, the position of the weights is moved or changed by a sliding movement of the hydraulic piston so that an amplitude of the vibratory movement is varied.
However, in the conventional vibration mechanism of a dual-axis structure which has a single axis for serving as an inner cylinder and an outer cylinder, the entire structure of the mechanism is so complex that it is quite difficult to provide unbalanced positions of vibration by means of a phase difference and to control or regulate the position of the weights. Thus, it has been difficult to incorporate and assemble the vibration mechanism into the apparatus, and substantial labor is required to maintain of the apparatus.
It has been attempted to provide two vibratory shafts of a dual axis structure are provided into a central portion of the vibration table so that the inner cylinder serves as an unbalanced shaft having a weight. The unbalanced shaft is provided with a helical cam groove and a control pin fitted to the helical cam groove so that the control pin is moved longitudinally to shift or change the phase of the weight to thereby obtain a predetermined vibration. This type of vibration mechanism, however, is still disadvantageous in that a sliding movement of the control pin relative to the helical cam groove is not as smooth as desired and it is likely that an undesirable displacement is generated, with the result that it has been difficult to obtain a predetermined, constant vibration to an entire area of the vibration table.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a new variable amplitude type vibration apparatus which has a simple structure and which overcomes the disadvantages and difficulties inherent in the conventional apparatus described above.
Accordingly to the present invention, two pairs of two-vibration shaft (dual shaft) structures having an eccentric weight for producing vibration are arranged in a laterally symmetrical relation on the vibration table.
According to the present invention, there is provided a vibration apparatus for a variable amplitude type vibration table comprising:
a pair of vibration driving shafts disposed, in a parallel relation with each other, on a vibration table, each of the vibration driving shafts having an equivalent eccentric weight member,
motors for separately and independently driving each of the vibration driving shafts disposed,
a pair of vibration driven (follower) shafts, in a parallel relation with the vibration driving shafts, each having an equivalent eccentric weight, the eccentric weights of the vibration driven shafts being variable in phase relative to the eccentric weights of the vibration driving shafts,
geared pulleys disposed to an end of each of the vibration driven shafts,
timing belts engaged with the geared pulleys of an end of each of the vibration driving shafts through geared pulleys disposed on opposite ends of oscillating support arms, thereby forming a symmetrical reversing rotational transmission mechanism,
an interlocking link mechanism, driven by a single cylinder device and coupled with a pivotal axis of the oscillating support arms of a symmetrical configuration,
wherein a vertical vibration of the vibration table is solely varied between a minimum point to a maximum point in accordance with an extended length of a cylinder rod of the cylinder device.
In the structure described above, the interlocking link mechanism is arranged such that a pivotal axis of one of the oscillating support arms is located on the way of a crank portion coupled with an end of the cylinder rod and that an end of a connecting rod coupled with an end of the crank portion is located on a pivotal axis of the other of the oscillating support arms. The cylinder rod is extendable during the vibration of the vibration table to provide a continuous variability in amplitude of the vibration.
In the present invention, the vibration apparatus has two vibration driving shafts with equivalent eccentric weights and two additional vibration driven (follower) shafts with equivalent eccentric weights which are changeable in the phase thereof relative to the eccentric weights of the vibration driving shafts, so that the vibration driven shafts are rotatable in an opposite direction relative to the rotation of the vibration driving shafts through timing belts, in a symmetrical relation. Further, a change in phase of the weights of the vibration driven shafts is proceeded by a single cylinder in a stepless manner through the interlocking link mechanism. Thus, two pairs of the vibration driving/driven shafts, each having an equivalent eccentric weight, are provided in a symmetrical configuration as a whole and, therefore, vibration variety of the vibration table depends upon selection of the phase of the eccentric weights of both sides of the driving and driven shafts, so that a vertical vibration is generated in the range between a maximum level and a minimum level.
In other words, according to the present invention, in a case that the position (i.e., a phase) of the eccentric weights of each of the vibration driven (follower) shafts are set to be vertically symmetrical to the equivalent eccentric weights of each of the vibration driving shafts, the eccentric weights of the vibration driving shafts are positioned in a vertical (or up and down), symmetrical relation with respect to the eccentric weights of the vibration driven (follower) shafts and, therefore, vibrations in the vertical direction are offset or cancelled with each other to thereby provide a minimum amplitude. By contrast, a vibration in the horizontal (or, lateral) direction is offset or cancelled with each other to become zero (0) since the two pairs of the vibration driving shafts and vibration driven shafts are located in a symmetrical relation with each other.
If the position (phase) of the eccentric weights of each of the vibration driven shafts is set to be the same positional relation with respect to the position (phase) of the eccentric weights of each of the vibration driving shafts, a maximum amplitude in the vertical direction is obtained. In all of the phases from the minimum amplitude to the maximum amplitude, the vibration in the horizontal direction becomes offset or cancelled with each other, because the eccentric weights of the vibration driving shafts and the eccentric weights of the vibration driven shafts, two pairs in all, are laterally symmetrical and equivalent with each other.
In the vibration table described above, the vibration in the vertical direction is continuously varied from the maximum level to a minimum (stop) level by the shift of the position of the eccentric weights of the vibration driven shafts. However, with respect to the vibration in the horizontal direction, the entire positional relation (that is, a laterally symmetrical relation) is unchanged even if the position of the eccentric weights is changed and thus the horizontal vibrations are offset or cancelled
Adams & Wilks
Estremsky Sherry
Kabushiki Kaisha Kei
Lewis Tisha D.
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