Machine element or mechanism – Mechanical movements – Rotary to or from reciprocating or oscillating
Patent
1981-12-04
1986-02-18
Staab, Lawrence J.
Machine element or mechanism
Mechanical movements
Rotary to or from reciprocating or oscillating
74 55, 74 57, 74568R, F16H 2514, F16H 5308
Patent
active
045705003
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a cam driven mechanism for variably controlling the pressure, velocity, and stroke displacement of a ram or lever. The ram is particularly used in punch and draw presses, and riveting machines (Group A machines); and the lever as particularly used in automatic screw machines, feed mechanisms and indexing machines (Group B machines).
In subsequent paragraphs the invention is described in connection with the above identified machine groups. However, it should be understood that the invention is applicable to other machines that use a reciprocating work shaft i.e., ram or lever.
BACKGROUND ART
Group A Machines: Conventional punch and draw presses, and riveting machines supply flywheel energy to the dies via an eccentric, pitman arm, ram, clutch, and a brake. The clutch is used to transfer the energy from the flywheel to the ram and the brake is used to stop the motion of the ram at the top of the ram stroke. The ram stroke displacement is fixed by the "throw" of the crankshaft and the rated pressure of the press is available only at the bottom of the ram stroke.
Group B Machines: Automatic screw machines that have multiple spindles employ several cylindrical type cams and have a single clutch located on the main driveshaft. When the clutch is activated all the tool slides converge on the rotating bar stock at the same time yet each tool must be individually adjusted.
Automation equipment as applicable to feed mechanism and indexing machinery is comprised of a clutch, reduction gear and indexer.
Some of the technical problems inherent in Group A machines include the following:
a. The energy supplied by the flywheel to the crankshaft and ecentric can only be extracted at the end of the ram stroke.
b. The ram stroke displacement is fixed and is limited to two times the eccentric of the crankshaft.
c. The pitman arm induces oblique forces into the dies.
d. The flywheel, clutch, brake, pitman arm, ram and other related parts sometimes work against each other during operation.
Some of the technical problems inherent in Group B machines include the following:
a. The toolslides in automatic screw machines are difficult to adjust because all the tool slides converge on the rotating bar stock at the same time.
b. Feed mechanisms and indexing machines have a clutch on the highspeed end of the drive. When the clutch is disengaged the feed or indexing cycle may not stop at the zero point, but rather proceed into the next cycle, which may cause a restart problem.
The background art as applicable to known prior art patents did not disclose any mechanisms or apparatus that read on the claims or are described in the specification of the instant application: Woodson in U.S. Pat. No. 2,429,084 discloses an adjustable cam that relates to automatic control mechanisms for initiating and timing a cycle of operations. This cam is especially adaptable for use on automatic clothes washing machines. Place in U.S. Pat. No. 2,598,427 discloses an apparatus adaptable to draw presses for controlling the blank being drawn and means for adjusting the timing of the control operation of die members without dismantling the machine. Puddingham in U.S. Pat. No. 3,546,993 discloses a locating device for use in effecting the relative location of the work and tools in a machine such as a punch press. Sabotta in U.S. Pat. No. 4,069,724 discloses a cam and follower construction in which a flat plate has a plurality of cam grooves intersecting each other with a cam follower engaging each of the cam grooves. A method is disclosed to insure that each follower stays in its own groove and does not accidentally pass into the wrong groove at the point of intersection.
DISCLOSURE OF THE INVENTION
The invention consists of a cam-driven mechanism for variably controlling the pressure, velocity, and stroke displacement of a ram or lever: the ram as particularly used in punch and draw presses and riveting machines (Group A machines), and the lever as particularly used in automatic screw machines, feed mechanisms an
REFERENCES:
patent: 236144 (1881-01-01), Clark
patent: 449572 (1891-03-01), Cameron
patent: 1280912 (1918-10-01), Waterman
patent: 3224283 (1965-12-01), Pilia et al.
patent: 3628645 (1971-12-01), McFeaters et al.
patent: 3865253 (1975-02-01), Healy
Cota Albert O.
Staab Lawrence J.
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