Robots – Protective device
Reexamination Certificate
1999-05-07
2001-04-10
Browne, Lynne H. (Department: 3629)
Robots
Protective device
C403S013000, C403S031000, C403S041000, C403S024000, C403S322100, C074S490010, C200S061410, C318S563000, C188S15100A, C901S011000, C414S735000
Reexamination Certificate
active
06214057
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to overload protection or safety coupling devices for robotic tooling and of the general type disclosed in U.S. Pat. No. 4,954,005 which issued to the assignee of the present invention, and also as disclosed in U.S. Pat. No. 4,842,114 and No. 4,540,331. Such a safety or protection device is used between the end of an arm of a robot and the tooling carried by the arm and provides for opening an electrical control circuit to the shut down of the robot in the event the predetermined movement of the tooling by the robotic arm is accidentally blocked by an obstruction or by non-compliant movement of the robot arm due to a malfunction of the robot.
With any such safety or protection device, it is desirable for the device to operate and open the control circuit quickly in the event there is any rotational and/or tilting and/or axial movement of the tooling relative to the end of the robot arm. It is also desirable for the device to reset automatically with high return accuracy after the blockage is removed or the reason for the relative movement between the arm and the tooling is corrected. It has also been found desirable for the device to be compact with a low profile and have a high load capacity so that the robot arm may quickly move tooling having substantial size and weight or mass. While the safety or protection devices disclosed in the above patents provide some of the above desirable features, the devices have limitations which prevent the devices from providing all of the desirable features.
SUMMARY OF THE INVENTION
The present invention is directed to an improved overload safety or protection device which provides all of the desirable features mentioned above and which may also be efficiently manufactured. The protection device of the invention may also be conveniently adjusted for precisely selecting pre-trip compliance or the small degree of relative movement between the robot arm and the tooling before the electrical circuit opens and the robot shuts down.
In accordance with a preferred construction of the safety or protection device of the invention, a cup-shaped cap member defines a cavity which receives a smaller and opposing cup-shaped yoke member having three angularly spaced ears projecting outwardly into portions of the cavity. The yoke member defines a fluid chamber which receives a piston having a rounded end surface engaging the cap member. A set of three chrome steel balls are secured to the ears of the yoke member, and an annular cam member is inserted into and secured to the cap member. The cam member has three angularly spaced V-shaped cam surfaces with V-shaped center seats normally engaged by the steel balls. A plastic ring is carried by the yoke member and contacts a shoulder within the cam member. A switch base is adjustably positioned within the yoke member and carries a pair of normally closed spring metal electrical contact elements. An actuator pin is carried by a center portion of the piston and is effective to separate and open the contact elements in response to either tilting and/or rotational and/or axial movement between the cap and yoke members.
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Gardner Michael P.
Haaren Beth Van
Spencer Graham T.
Browne Lynne H.
Garcia Ernesto
Jacox Meckstroth & Jenkins
Process Equipment Co. of Tipp City
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