Machine element or mechanism – Control lever and linkage systems – Multiple controlling elements for single controlled element
Patent
1989-10-17
1992-01-07
Braun, Leslie A.
Machine element or mechanism
Control lever and linkage systems
Multiple controlling elements for single controlled element
74 57, 74665C, 74411, 74470, 414590, 901 49, G05G 1100, F16H 2516, B25J 1900
Patent
active
050780212
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a multi-axis mechanical manipulator with adjustable travel and with complete protection against overloads.
2. Description of the Prior Art
A wide variety of bi- or triaxial mechanical manipulators already exists, differing principally in the indexing mechanism used: global cam, paired flat cams, and cylindrical cams. This last means is reserved principally for triaxial mechanical manipulators.
Nevertheless, despite the undeniable advantages of compact construction, high precision, high transfer speed, controlled acceleration, positive positioning, reduction of idle time, and so forth that these indexing mechanisms offer, they have the disadvantages associated with rigidity, which are: and are not adjustable; deceleration conditions, which yield a maximum speed at mid-course; majority of cases the indexing mechanisms are driven by a sliding rotor motor and a worm wheel reducing gear.
Moreover, if the output shaft becomes stuck in the locked position, there is a risk that the rollers or cam will break, because they are located in the zone of stoppage of the cam.
The angle of cam/roller pressure is equal to zero, so that in the presence of even slight torque exerted on the camshaft the forces on the rollers tend to infinity.
To prevent the risk of breakage, torque limiters that are triggered in the case of blockage are typically used, but they entail the following disadvantages: must be searched for; this requires precise knowledge of the material and often as a result means a stoppage in production, resulting in losses in productivity; become dangerous, especially for vertical movements; consequently precludes its being used for high-precision indexing or positioning applications.
An overload protector for mechanical manipulators is already known such as that described in French Patent Application FR A 2.451.250, which relates to materials handling apparatus including two cylindrical cams, the second of which is associated with a roller mounted in such a way that it can oscillate about an axis transverse to that of the cam, so that in combination with a means for disengagement in the case of overload, such as a spring engaging and disengaging means, it can permit a movement of the cam in question without being accompanied by a movement of the grasping means when the latter encounters an obstacle. Nevertheless, the disengagement means used (the spring engaging and disengaging means functioning as a torque limiter) necessitates searching for the initial position of the manipulator arm after use, with the attendant interruption in production.
SUMMARY OF THE INVENTION
The invention seeks to overcome the above disadvantages and to solve the problem of creating a multi-axis mechanical manipulator offering opportunities for travel adjustment, and total protection against overloads, without losing the advantages of the mechanical system in terms of reliability.
The mechanical manipulator according to the invention is characterized principally in that the drive of the indexing mechanism is assured by the combination of a sliding rotor motor, a worm wheel reducing gear, and an adjustable torque limiter. The law of motion of the indexing mechanism is determined so as, in combination with the aforementioned torque limiter, to obtain a constant speed over a wide range, thus offering the possibility of optional stopping and hence of travel adjustment. The rotational motion transmitted to the cylindrical cam is effected via an adjustable torque limiter; and the drive of the manipulator arm is effected via a spring plate with adjustable tension, enabling a momentary angular retraction of the arm when it encounters an obstacle.
The torque limiter of the indexing mechanism is a friction limiter with springs the tension of which is adjustable directly or remotely via jacks.
In a preferred embodiment of the invention, the adjustment of the tension of the springs of the torque limiters of the indexing mechanism and of the cylindrical cam is accomp
REFERENCES:
patent: 2579642 (1951-12-01), Bachman
patent: 3080765 (1963-03-01), Eisele
patent: 3359819 (1967-12-01), Veillette et al.
patent: 3406583 (1968-10-01), Baier
patent: 4293268 (1981-10-01), Mink
patent: 4344729 (1982-08-01), Orsinger et al.
patent: 4514616 (1985-04-01), Warner
patent: 4639184 (1987-01-01), Knasel et al.
patent: 4741642 (1988-05-01), Carlton
patent: 4770055 (1988-09-01), Chevance et al.
Braun Leslie A.
Krolikowski Julie
S.O.P.A.P. Limited Company
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