Presses – Reciprocating press construction – With mechanical force multiplier
Reexamination Certificate
1999-06-04
2001-03-13
Vo, Peter (Department: 3721)
Presses
Reciprocating press construction
With mechanical force multiplier
C100S283000, C100S285000, C072S451000
Reexamination Certificate
active
06199478
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a press machine of the class in which the first and second crankshafts are connected with each other by means of a link and a pair of levers
2. Prior Art
In general, the press machine utilizing a link mechanism like a knuckle joint, a toggle joint and so forth, may be classified into two types, of which one is provided with a crankshaft rotated by a power or driving source while the other includes a driving crankshaft rotated by a driving source, and a driven or coupled crankshaft which makes the rocking motion or swing motion by rotation of the driving crankshaft. The press machine provided with two crankshafts has advantageous features than the press machine with a single crankshaft as described in the following.
In case of the press machine with two crankshafts, the upper portion of a slide can be connected with a plurality of rods (for instance, three or more rods), which can be driven by using a pair of link levers and the coupled crankshaft. The moment of inertia of the crankshaft itself is relatively small so that the time necessary for starting and stopping the operation of the press machine is made shorter, which allows the press machine to show the excellent performance and to operate at high speed. In addition, the number of parts constituting the press machine can be reduced, which again allows the press machine to operate at high speed.
An example of the press machine using a link mechanism is disclosed un the Japanese patent public diclosuer (KOKAI) No. 9-225686. This prior press machine is provided with a crankshaft rotated by a driving source and a bell crank mechanism connected with the eccentric shaft portion of the crankshaft, thereby enabling the slide to move in the up and down directions.
However, as described above, since this prior art press machine employs the bell crank mechanism as a transmission mechanism for converting the rotary motion of the crankshaft into the power for use in moving the slide in the up and down directions, the number of parts constituting the transmission mechanism is naturally increased. Increase in the number of parts constituting the transmission mechanism not only makes the structure of the transmission mechanism complicated, but also makes the force of inertia larger. Therefore, this is not suitable for operation of the press machine at high speed.
Thus, in the press machine of this class, it is of importance to reduce the number of parts constituting the transmission mechanism for transmitting the rotary motion of the crankshaft rotated by the driving source to the slider.
SUMMARY OF THE INVENTION
According to the invention, there is provided a press machine which includes a frame, a first crankshaft rotatively arranged on the frame, a second crankshaft arranged on the frame so as to rotate angularly, a pair of levers connected with each other such that they can make a bending and stretching motion, one lever being connected with the frame such that it can make a pivotal motion but can not be relatively displaced, the other lever being pivotally connected with the eccentric shaft portion of the second crankshaft, and a link which connects the levers with the first crankshaft and bends and stretches both of the levers as the first crankshaft is rotated.
Both levers are bent and stretched by the link as the first crankshaft is rotated, thereby causing the second crankshaft to make a rocking motion. The rocking motion of the second crankshaft is transmitted to the slide, thereby the slide coming to reciprocate in the up and down directions.
As described above, as the press machine of the invention is provided with the second crankshaft, the rotary motion of the first crankshaft is converted into the rocking motion of the second crankshaft with the help of the link and both of levers and is then transmitted to the slider. With this, there can be a remarkable reduction in the number of parts constituting the transmission mechanism for transmitting the rotary motion of the first crankshaft rotated by the driving source to the slide.
In a preferable embodiment according to the invention, the second crankshaft includes a principal shaft portion arranged on the frame so as to make a rocking motion, a first eccentric shaft portion pivotally connected with the above other lever, and a second eccentric shaft portion connected with a slide.
A press machine according to the invention may further include a connection piece connected with the eccentric shaft portion of the second crankshaft and moves the slide in the up and down directions as the second crankshaft makes the rocking motion. Furthermore, a press machine according to the invention may include rods arranged on the frame so as to move in the up and down directions and are pivotally connected with both of the slide and the connection piece.
REFERENCES:
patent: 2562044 (1951-07-01), Klocke
patent: 3791191 (1974-02-01), Baldyga
patent: 6012322 (2000-01-01), Itakura
patent: 1153251 (1963-02-01), None
patent: 09225686 (1997-09-01), None
Huynh Louis
Ipsolon LLP
Kabushiki Kaisha Yamada Dobby
Vo Peter
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