Elongated-member-driving apparatus – With control means responsive to sensed condition
Patent
1997-10-15
1999-09-28
Vo, Peter
Elongated-member-driving apparatus
With control means responsive to sensed condition
227 30, 227 31, B21J 1528
Patent
active
059573627
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to an apparatus for attaching rivets, buttons or the like as well as to a control for such an apparatus.
Attaching machines for attaching rivets, buttons or the like are known in the prior art. As a rule, there is a bottom tool and a bottom tool in such machines. A plunger is associated with the top tool. The plunger interacts with a cam plate. The shape of the curve on the cam plate determines the course of movement of the plunger. The cam plate is driven by an electric motor, and the movement sequence per unit of time, in particular the cycle rate of the plunger stroke, is determined by the rotational speed of the electric motor. As a rule, the known attaching apparatuses have finger protection; the latter consists of a feeler element which senses whether an object, in particular a finger, is lying between the top tool and the textile. If such an object is sensed there, a brake which stops the motor comes into action immediately, so that the plunger pauses on its path of movement.
If a multiplicity of rivets or the like are to be attached within a sequence by such a known attaching apparatus, a switch, in particular a foot switch, is actuated, which causes the motor to start up. The cycle rate is determined by the rotational speed of the motor. In many cases, it is desirable to influence, in particular reduce, the cycle rate. In the case of machines of the prior art, the motor can be made to run at a correspondingly slower speed for this purpose. This is accompanied by a reduction in the downward speed of the plunger and thus influences the riveting speed. Consequently, the quality of the riveting or attachment is not uniform.
SUMMARY OF THE INVENTION
The object of the invention is to develop an apparatus of the present type in a functionally advantageous manner.
As a result of the present invention, an apparatus is provided in which the plunger is always displaced downward at the same preset speed irrespective of the cycle rate. The cycle rate is now set by a brief stoppage of the apparatus at the top dead centre of the plunger position. In this case, the waiting time of the drive is in the range of milliseconds. The motor is preferably driven by an electronic control unit which determines the motor position, in particular the top dead-centre position of the plunger, by sensor means or the like. If the drive reaches the top plunger position, the electronic control unit immediately interrupts the motor current supply and brakes the motor. An eddy-current brake or a friction brake may be provided for braking the motor. After the waiting time has passed, the braking action is neutralized and the current supply to the motor is started again. The electronic control unit may contain a microprocessor or a microcontroller. A key input is provided. To this end, an upcount key and a downcount key may be provided in the electronic control part. By actuation of the said keys in a prescribed program menu, the waiting time can be set in steps. The step size is preferably 10 milliseconds. The waiting time can preferably be set in a range of 0-990 milliseconds. Furthermore, the electronic control unit may contain counters. In this case, a first counter can count the attachments effected in a sequence. A second counter serves to indicate the total number of working strokes performed by the apparatus. The indication may be effected via an electronic display. Furthermore, provision is made according to the invention for the electronic control unit to be likewise able to program the rated motor current. In a prescribed program menu, the motor can be adapted by key actuation to the main power supply voltage available at the place of installation. Provision is also made for a multiplicity of different articles to be attached one after the other in a prescribed order within one attaching sequence. If the articles lie at different spacings apart on the textile, provision may also be made for an individual waiting time to be allocated to each working stroke within
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Hardt Manfred
Samulowitz Helmut
Calve James P.
Farber Martin A.
Vo Peter
William Prym GmbH & Co. KG
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