1. Field of the Invention
The invention relates to cycloidal drives, and more particularly to drives for reciprocating parts which require speed reduction during intermediate portions of their strokes. An example of such driven parts is a mechanical welding press which requires a mid-stroke slow down so as to minimize shock to parts when they are being lifted from automation rails, and reduce the noise level inherent with this shock condition. Another example is an automation system in which a reciprocating shuttle on a conveyor must be slowed down at mid-stroke for similar purposes.
2. Description of the Prior Art
Gervais U.S. Pat. No. 3,559,767 shows a planetary gear system with a crank arrangement describing an epicycloidal path in order to reduce the platen speed at certain points in the motion. This patented construction has a number of disadvantages as compared with the apparatus of this invention. It utilizes two fixed external sun gears and pin-ended joints, thus requiring two primary gear assemblies and making it impossible, because of the geometry of the construction, to support the bull gear shafts at opposite ends. Instead they must be cantilever mounted. It is further believed that the Gervais construction would not be interchangeable with most present day welding press configurations.
Matsushita U.S. Pat. No. 3,971,261 pertains to a slide driving device for use in metal working presses which is of the cycloidal type. This patent utilizes an external fixed gear and exhibits certain disadvantages as compared with the present invention which will become apparent from the following description.
Seki U.S. Pat. No. 3,956,942 also illustrates a cycloidal arrangement in which there is a reduction of velocity in the center of the stroke. However the mechanism is substantially different than that of the present invention, and advantages of the present invention wll become apparent below.
The following patents are of interest insofar as they pertain to either cycloidal gear trains or to gear train arrangements having some features pertinent to the present invention:
Staecker et al: U.S. Pat. No. 2,822,696 PA1 Fracke: U.S. Pat. No. 3,468,173 PA1 Koderman: U.S. Pat. No. 3,886,805 PA1 Hosoda et al: U.S. Pat. No. 3,921,465 PA1 Mori et al: U.S. Pat. No. 3,960,024 PA1 Obra: U.S. Pat. No. 4,020,708 PA1 Obra: U.S. Pat. No. 4,089,228 PA1 Drungil: U.S. Pat. No. 4,095,522