The invention relates to an apparatus for treating the leads of electrical components, such as transistors or the like, with a carrier plate rotatable about a fixed axis of rotation having at least one tool set arranged at the periphery of the carrier plate consisting of a stationary tool and a tool pivotable about a pivot axis in parallel to the axis of rotation, wherein the pivotable tool, during the rotation of the carrier plate, is controllable by an operating cam section of a fixed cam disk from an open position into a closed position (applicant's U.S. Patent Application Ser. No. 888,146, filed Mar. 20, 1978). In this connection, a pivotably mounted ejector lever can furthermore be provided.
The invention is especially directed toward the preparation of the leads of transistors, but basically relates to all components wherein the leads are likewise arranged only on one side of the body of the component. The treatment to which these leads are subjected involves primarily bending, crimping, and cutting to length, i.e. measures by which the transistors are prepared for insertion in a circuit board. In this process, according to my U.S. Ser. No. 888,146 with respect to which the present application represents an improvement, the components are fed from a storage container, which is fashioned, for example, as a vibrating pot, via a conveying means in close succession to the tools. The conveying means has a transfer slot at the point at which the components are transferred to the tools, this slot being arranged approximately at the level of the tools and extending in the peripheral direction of the tools, and furthermore being open in this direction. Respectively, one component is disposed in this slot with leads extending downwardly through this slot. During the revolution of the carrier plate, respectively one component is seized, in the open position of the tools of a tool set, by the fixed tool trailing in the peripheral direction and thereafter, upon controlling the pivotable tool so that is assumes its closed position, is clamped between the tools and treated.
After the treatment, during the transition into the open position, the thus-prepared components must be ejected from the tools. For this purpose, an ejector lever is provided, pivotably arranged at the fixed tool and/or at the carrier of this tool, this lever being pulled by a spring into a rest position not impeding the tools and being pivotable outwardly by means of a stationary stop.
This apparatus, which is the subject matter of my abovenoted application, has proven itself excellently, per se. However, certain problems arose when the peripheral speed of the carrier plate was increased to enhance the operating efficiency. According to the suggestion advanced by myself in Ser. No. 888,146, the pivotable tool as well as the ejector lever are positively actuated only in one direction, namely toward the closed position and/or toward the ejection position. The resetting in the opposite direction, i.e. into the open position of the tools and/or the rest position of the ejector level, in contrast thereto, is effected by spring force. If the springs provided for this purpose do not have a sufficiently strong design, then an accurate chronological control of the operating cycle is no longer ensured at higher operating speeds. On the other hand, if these springs are made to be sufficiently strong, then considerable forces must be expended during the operation of tools and ejector lever, leading accordingly to undesirably high stresses on the material and considerable noise generation.
Therefore, an object of the invention is to provide an apparatus which cures the problem described hereinabove so that higher operating velocities can be attained without undue stresses on the material and with minimum noise generation.
This problem has been solved, in accordance with a preferred embodiment according to the invention, in that the cam disk is additionally provided with an opening cam section, and that the pivotable tool can be operated by the opening cam section to assume, from the closing position, the opening position. Thus, the preferred embodiment realizes a positive control of the pivotable tool, which entirely eliminates a spring for returning the pivotable tool into the open position. Since, consequently, only inertial forces rather than spring forces need to be overcome when changing from the open position into the closed position, as well as vice versa, the possibility is obtained to exert an exact control of the chronological cycle even at high rotational speeds, wherein the occurring accelerations can be maintained within the permissible limits by an appropriate design of the operating cam section and the opening cam section.
Preferably, respectively one scanning roller (closing roller and opening roller) is associated with the operating cam section and the opening cam section, these rollers being connected to the pivotable tool. The scanning rollers are mountable directly to the tool, but they are preferably arranged at the appropriate tool holder. In any event, this arrangement makes it possible to effect a separate adjustment for the opening step and the closing step. The operating cam section must expend not only inertial forces to accelerate the pivotal tool, but above all, also the treatment forces. Accordingly, the operating cam is designed to be strong and is customarily machined "from a solid piece."
The opening cam section, however, need merely provide inertial forces and thus can be made to be less rugged. Thus, there is the possibility of forming the opening cam section by a sheet-metal strip attached to the periphery of the cam disk; in this way, an apparatus according to my above-noted application can be modified in a simple way.
Furthermore, it is contemplated within the scope of the present invention to arrange the scanning rollers coaxially to each other and accordingly disposing the operating cam section and the closing cam section offset with respect to each other in the direction of the axis of rotation. An independent synchronization of the opening and closing operations can be effected by an appropriate selection of the diameters of the scanning rollers.
The above-discussed problems are encountered to a particularly great extent in connection with the ejection of the components, which have been treated, during the opening of the tools. At higher operating velocities, the ejection does not take place in a reliable fashion, which can lead to considerable disturbances in the operating cycle.
In this respect the invention teaches an especially advantageous embodiment, which is characterized by a carrier arm connected to the pivotable tool--or to the tool carrier itself--and being in engagement with the ejector level. By the carrier arm, the adjustment of the pivotable tool is also utilized for operating the ejector level. The connection of the carrier arm with the pivotable tool proves to be much less expensive than a direct cam disk control of the ejector lever. At the same time, the possibility is attained of providing an exact and unequivocal temporal synchronism between the opening of the tools and the ejection of the components. In this connection, the ejection takes place perforce from the opening cam section side and thus at maximum reliability.
Considering the manufacturing tolerances, it is advantageous to design the engagement of the carrier arm at the ejector lever so that it has at least a certain amount of play or can be effected at all merely in the opening direction, while the ejector lever--as described in Ser. No. 888,146--is pulled in the opposite direction by spring force. Such an engagement can be attained, for example, by providing that the carrier arm extends with a claw behind a projection and/or pin at the ejector lever, or that the carrier arm engages with a pin into a slotted hole of the ejector lever. Furthermore, the carrier arm can be rigidly joined to the pivotable tool and/or its tool carrier, or it can be pivotally attached thereto and maintained in engagement by means of spring force.
It is expedient to mount the ejector lever to be pivotable about an axis in parallel to the axis of rotation, namely preferably directly to the fixed tool, so that a compact module results.
The respective treatment to be conducted may make it necessary to provide the tools with several so-called combs [serrated elements] which cooperate in pairs during the closing step. Independently of the objective of the treatment, this feature is also advantageous with a view toward a precise guidance of the components during ejection, and in this connection the invention teaches to provide at least two of such combs and to arrange the ejector lever between the combs of the fixed tool. In this connection, the advantageous possibility is obtained, in particular, of fashioning the ejector lever proper as a comb and thus use same during the treatment, for example, for the crimping or bending of the leads. The ejector lever is, in any event, disposed in parallel to the combs, which latter constitute more or less planar structures, and is nestled between these combs, which results in a secure and non-tilting engagement at the leads of the components.
In another advantageous embodiment, the ejector lever has two mutually parallel ejector arms joined together by a connecting web with the formation of a U-shaped cross section and enclosing between them one of the combs of the fixed tool. In this arrangement, an extra-ordinarily compact structure results ensuring an extensively straight and thus troublefree ejection of the components. Preferably, the ejector arms enclose between them the uppermost of the combs of the fixed tool, so that the lower one of the ejector arms engages the leads and the upper one engages the housing of the components. In the embodiment described in the above noted application with tension relief of the leads during the treatment by means of a holder and counter holder [bracket], it is especially advantageous to provide an arrangement wherein the ejector arms enclose between them the counter holder associated with the fixed tool and preferably also the uppermost comb of the fixed tool.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.
USPTO Backgrounds
USPTO Backgrounds