US3628723A

US3628723A - Operating member selection system

Info

Publication number: US3628723A
Application number: US878803A
Authority: US
Inventors: Kurt Ehrat
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1968-11-25
Filing date: 1969-11-21
Publication date: 1971-12-21
Anticipated expiration: 1988-12-21
Also published as: FR2024130A1; DE1958580A1; CH499830A; GB1249956A; NL6916289A

Abstract

In a system for selectively operating the punches of tapepunching devices, wherein a tappet is hingedly deflected by the armature of an electromagnet, the momentum of a reciprocating member carrying the tappet is used for presenting the armature to the core of the electromagnet and this, in combination with the storage of energy in a torsion member interconnecting the armature and the tappet, makes it possible to rely on minimal magnetic forces and hence to use relatively weak magnetic forces to achieve an optimum operating frequency of the tappet as well as maximum speed and precision without at the same time making stringent demands upon the accuracy of the timing periods of electromagnet energization and deenergization. The tappet is mounted on top of the reciprocable member and the latter has an extension which as it rises, engages the armature and raises it also, towards the core. A control unit energizes and deenergizes the electromagnet in synchronism with the operating cycle of the reciprocating member and the latter has two abutments defining first and second positions between which the tappet moves, a punch-operating member being displaceably mounted above the tappet in one of said positions. Preferably the armature is urged onto said extension by spring means and a lost motion coupling is provided between the spring means and the armature.

Description

United States Patent [72] inventor Kurt Ehrat Zurich, Switzerland [2 l] Appl. No. 878,803 [22] Filed Nov. 21, 1969 [45] Patented Dec. 2!, 1971 [73] Assignee Ciba-Geigy AG Basel, Switzerland [32] Priority Nov. 25, 1968 [33] Switzerland 3 l 17516/68 [54] OPERATING MEMBER SELECTION SYSTEM 11 Claims, 6 Drawing Figs.

[52] US. Cl. 234/115 [51 I llll. Cl. G06k 1/05 [50] Field Search 235/115, 1 19 [56] Relerences Cited UNITED STATES PATENTS 3,133,698 5/1964 Hergert 235/115 3,268,163 8/1966 Ehrat 235/115 X 3,459,370 8/1969 Eissfeldt et 31.. 234/115 3,462,077 8/1969 Pozzi 234/1 15 Primary Examiner-William S. Lawson AttorneyPierce, Scheffler & Parker ABSTRACT: In a system for selectively operating the punches of tape-punching devices, wherein a tappet is hingedly deflected by the armature of an electromagnet, the momentum of a reciprocating member carrying the tappet is used for presenting the armature to the core of the electromagnet and this, in combination with the storage of energy in a torsion member interconnecting the armature and the tappet, makes it possible to rely on minimal magnetic forces and hence to use relatively weak magnetic forces to achieve an optimum operating frequency of the tappet as well as maximum speed and precision without at the same time making stringent demands upon the accuracy of the timing periods of electromagnet energization and deenergization. The tappet is mounted on top of the reciprocable member and the latter has an extension which as it rises, engages the armature and raises it also, towards the core. A control unit energizes and deenergizes the electromagnet in synchronism with the operating cycle of the reciprocating member and the latter has two abutments defining first and second positions between which the tappet moves, a punch-operating member being displaceably mounted above the tappet in one of said positions. Preferably the armature is urged onto said extension by spring means and 1 a lost motion coupling is provided between the spring means and the armature.

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OPERATING MEMBER SELECTION SYSTEM This invention relates to a system for selectively coupling an element, such as a punch, which is displaceable from a position of rest against the reactive thrust of a restoring force, to a reciprocable member.

In such a system the member is reciprocated by a motor or by magnetic means and carries a hinged tappet which is deflectable about its hinge by the armature of an electromagnet. By virtue of the tappets geometrical configuration in one position loosely couples the displaceable element in its position of rest to the reciprocating member, and the electromagnet is electrically connected to a magnet-energization control unit which synchronizes the intervals of magnet energization and deenergization with the operating cycle of the reciprocating member. The mechanical connection between the armature of the electromagnet and the tappet, which reciprocates with the reciprocating member, is provided by a flexible torsion shaft.

Such arrangements are used more particularly for selectively operating the punches of tape-punching devices. In such devices it is the aim to couple selectively with maximum possible speed the several punches to a single actuating member for the duration of one or more reciprocating cycles. The required coupling and uncoupling times are in the order of milliseconds. The problems involved in achieving this aim have not to the applicant's knowledge yet been satisfactorily solved.

It is the object of the present invention to provide an im proved form of' system for the selection of elements such as tape punches.

In accordance therefore with the present invention we provide an operating member selection system comprising:

a reciprocable member a tappet means pivotally mounting said tappet to said reciprocable member,

an electromagnet,

an armature attractable by said electromagnet upon energization thereof,

an element coupled to said reciprocable member and positioned to engage said armature and move it towards said electromagnet. upon an upward reciprocating stroke of said reciprocable member,

a torsion member coupling said armature to said tappet and urging said tappet from a first to second position upon movement of said armature towards said electromagnet,

an operating member positioned for engagement with and displacement by said tappet when said tappet is at said second position, and obstruct movement of said tappet from said first to said second position during at least part of the downward stroke of said reciprocable member, electromagnet energization means responsive to the reciprocating movement of said reciprocable member to energize said electromagnet during at least the latter part of the downward stroke of said reciprocating member and attract said armature to cause said torsion member to urge said tappet toward said second position and allow said tappet to move to said second position when the tappet is unobstructed by said operating member during said downward reciprocating stroke to effect engagement and dis placement of said operating member by said tappet on the subsequent upward reciprocating stroke of said reciprocable member.

By utilizing the momentum of the reciprocating member for presenting the armature to the core of the electromagnet in combination with the storage of energy in the torsion member it is possible to rely on minimal magnetic forces and hence to use relatively weak magnetic forces to achieve an optimum operating frequency of the tappet as well as maximum speed and precision without at the same time making stringent demands upon the accuracy of the timing periods of electromagnet energization and deenergization.

In order that the nature of the present invention may be more readily understood an embodiment thereof will be hereinafter more particularly and illustratively described with reference to the accompanying drawings in which FIG. 1 is a perspective view of an embodiment of the invention FIG. 2 is a variant of a detail of the arrangement in FIG. 1, likewise in perspective,

FIG. 3 is a diagram by reference to which the manner in which the arrangement in FIG. 1 functions will be explained, and

FIGS. 4 to 6 illustrate an application of the arrangement according to FIG. 1, FIGS. 4 and 5 being side views and FIG. 6 a view from above.

The system illustrated in FIG. 1, provides a reciprocating member 1, a displaceable element 2, a tappet 3, an electromagnet 4, an armature 5 associated with the electromagnet, and a deflecting torsion shaft 6. The member 1 is reciprocated by a

crank drive

7, 8, 9 on the end of a shaft 9 driven by a motor not shown in the drawing. The displaceable element 2 has mounted thereon a collar 11 which is kept in contact with one arm of a sliding bearing l2 in which the displaceable element is mounted by a compression spring 10. The tappet 3 is pivotally mounted on the reciprocating member 1 and deflectable by energization of the electromagnet 4. The deflecting motion is transmitted from the armature 5 of the electromagnet to the tappet 3 by the flexible torsion shaft 6. The angle of deflection of the tappet 3 is limited by abutments l6 and 17. In the illustrated embodiment the configuration of the armature 5 is that of a hoop and in the course of each upstroke of the reciprocating member 1 an extension arm 15 on the latter lifts the armature and presents it to the core of the magnet 4 from whence it is retracted by a tension spring 18 if the magnet is not energized.

The electromagnet 4 is connected to a magnet-energization control unit 14 which converts input signals StB into energizing and deenergizing periods in synchronism with the operating cycle of the reciprocating member 1. The phase of these reciprocations is sensed by a magnetic pickoff 13 which generates an alternating current [81 representing the operating frequency of the reciprocating member and transmits this to the control unit 14. Instead of providing a magnetic pickoff some alternative sensing device such as a photoelectric detector could be employed. In the proposed arrangement the demands made upon the precision of the pickoff are not very stringent.

.The tappet 3, as illustrated is wedge shaped and cooperates with a similarly shaped head 20 on the displaceable element 2. The tappet is preferably much longer in the direction of its pivot axis than it is across the axis. This enables the moment of inertia of the tappet about its pivot axis and hence the torque required for deflecting the same to be minimized and at the same time the surface area of its head for cooperation with the head 20 of the displaceable element to be relatively large. The specific contact pressure in the operative position of the tappet can thus be reduced sufficiently to permit the tappet to be made of a material of low specific gravity, for example of plastics. Moreover, the cooperating contacting surfaces of the tappet and of the head 20 of the displaceable element can be so contrived that even slight pressures will not accidentally deflect the tappet out of contact with the element 20. The deflecting shaft 6 may consist of spring wire and or it may be combined with a coiled torsion spring 60. Alternatively, the hoop-shaped armature 5 and the deflecting shaft may be of integral construction. I

In a preferred modification of the arrangement the mechanical part of the armature control means may be so contrived that one end of the restoring spring (18) is attached in a manner providing some play to the armature or a part participating in the armature motion and the other end to the reciprocating member (1) or a part participating in the motions of the reciprocating member. The principal advantage of this novel arrangement is that the provision of play at the end of the mechanically induced motion presenting the armature to the magnet core, relieves the energized magnet from the necessity of overcoming the reaction of the restoring spring in fully attracting the armature. The reliability of magnetic retention of the armature is thereby improved and the necessary magnetic force further reduced. On the other hand, in the event of the magnet not being energized the retraction of the armature can be accomplished by taking advantage of the accelerating power of the reciprocating member which is a maximum at the points of reversal of the reciprocating motion. It has also been found that this improvement of the kinematics of the system leads to a significant reduction in wear. An embodiment of the above-described modification is illustratively shown in FIG. 2.

In FIG. 2 contact between the hoop-shaped armature and the extension arm of the reciprocating member is effected by a block element 19 which is urged by a restoring spring 18' against the extension arm, the hoop passing loosely through the element 19. The illustrated restoring spring 18 is a compression spring. Naturally a tension spring could be suitably disposed as an alternative, provided the spring urges the annature hoop with play against the reciprocating member or an extension thereof. For instance, a leaf spring might also be used of which one end is firmly attached to the reciprocating member 1 or its extension arm 15, whereas its other end is adapted to embrace the hoop 5 loosely for instance by means of an eyelet.

FIG. 3 graphically represents the motions S1 of the reciprocating member during a period exceeding two cycles (one cycle a complete reciprocation of the reciprocating member) as well as the motions S3 of the displaceable element. The drawing also indicates the energizing current I4 of the magnet, the corresponding positions of the armature 5 and of the tappet 3 at the times marked I-XIV, as well as the output current ISl of the pickoff 13. As shown the passages of this output current through zero lead the maxima ofSl by a time interval A. The magnet-energization control unit 14 (FIG. 1) is assumed to have been so designed and adjusted that the working periods of the magnet (current or no current) T coincide in time with the cycles T of the pickoff output current [51. During the period shown in the drawing the energizing current at the end of the working period T of the magnet is zero at the time II. This is also the case in the working periods beginning at the times VII (VIII) and XIII. During the intervening period II-VII the magnitude of the current flowing through the magnet is at least sufficient to hold the tar mature 5 which is mechanically presented to the magnet core (4) at the times lll, VIII, XIV, At the time I the reciprocating member is at its maximum distance from the displaceable member, the armature 5 is released (I4 being zero) and the tappet 3 is therefore in noncontact-making position in which it remains to the point in time marked IV. During the time interval l-III the armature 5 which participates in the motion 51 in one direction (i.e. the upward direction) is mechanically presented to the magnet core 4. This causes the torsionally elastic deflecting shaft 6 (FIG. I) to be torsionally strained between the armature and the tappet, the tappet being prevented from moving to a position in alignment with the element because it is obstructed by the displaceable element 20. During the time interval from III to VII the armature is retained by the energized magnet 4. The deflecting shaft therefore remains torsionally strained until the head of the tappet reaches the level SpZ (tappet free motion level). Upon clearing the displaceable element at the time IV the tappet is abruptly deflected from its noncontact making into its contactmaking position in which it remains at least to the time VIII of the next motion reversal of the reciprocating member, and in which it engages and lifts the displaceable element 2. At the time VII which closely precedes the time VII] the energizing current I4 is interrupted by the magnet-energization control unit, but between the times VII and VIII the residual excitation of the magnet and/or the reciprocating member keep the armature in operate position. During the intappet and the displaceable element, i.e. not later than when the point of contact between tappet and displaceable element reaches the tappet-free motion level SpZ (shortly before point XI). During the time interval XI-XIII the armature is again mechanically presented to the magnet by the ascending reciprocating member. The process then continues in the described manner.

As has already been mentioned (FIG. 1) the angle of deflection of the tappet 3 is limited by abutments l6, 17. As is symbolically indicated in FIG. 3, the maximum deflection angle ,8 of the tappet 3 is smaller than the deflection angle a of the armature 5 of the magnet. This arrangement operates firstly to increase the torsional strain of the deflecting shaft 6 (FIG. 1) and secondly to press the tappet in each of its end positions firmly against one of the abutments l6 and 17 by virtue of the residual torsional strain of the deflecting shaft, thereby ensuring that the tappet is firmly held in either position.

The operating conditions represented in FIG. 3 may be varied. For instance, the working interval T of the magnet need not necessarily be as long as one cycle T The working intervals must merely be so placed in time and of sufficient length to overlap the periods of time between the instants the armature is mechanically presented to the magnet and the end of the following free motion zone. As will be understood from FIG. 3 this free motion zone is upwardly limited by the free motion level SpZ, the tappet remains in the free motion zone for an interval in time marked 1.

The output current ISl of the pickoff can be used to control two sequences of magnet working intervals which are relatively displaced in phase by a half cycle by utilizing the intervals between the positive going passages through zero for one sequence and the intervals between the negative going passages through zero for the other sequence. This permits a displaceable element to be controlled in opposite directions by two correspondingly controlled tappets.

As has already been mentioned the proposed arrangement can be extremely compactly designed and is particularly suitable for selecting devices which permit several displaceable elements, such as punches, to be selectably operated by one reciprocating member. Two side views and one view from above of an arrangement of such a kind are schematically shown in FIGS. 4 to 6. In these drawings 1 is the reciprocating member, 2a to 2d are four controlled displaceable elements, 3a to 3d are four tappets, 4a to 4d are four associated electromagnets cooperating with four armatures (hoops) 5a to 5d, four deflecting shafts 6a to 6d, whereas the crank drive is indicated at 7, 8, 9. The tappets 3a to 3d and hence the controlled elements 211 to 2d can be selectably activated either severally or in groups.

I claim:

1. An operating member selection system comprising:

a reciprocable member including drive means coupled thereto for imparting a reciprocating motion to said member in a vertical direction,

a tappet pivotally mounted on said reciprocable member,

an electromagnet including an armature attractable thereto upon energization thereof,

a torsion member comprising a flexible shaft, one end of said flexible shaft being coupled to said armature and the other end of said flexible shaft being coupled to said tappet for urging pivotal movement thereof from a first position to a second position upon movement of said armature towards saidelectromagnet,

an extension arm on sai reciprocable member engageable with said armature for effecting movement of said armature towards said electromagnet upon an upward stroke of said reciprocable member, spring means loading said armature into engagement with said extension arm, an operating member positioned for engagement with and displacement by said tappet when said tappet occupies said second position and obstruct pivotal movement of said tappet from said first to said second position during IOIOIS 0243 at least a part of the downward stroke of said reciprocable member, and

electromagnet energization means responsive to the reciprocating movement of said reciprocable member to energize said electromagnet during at least the latter part of the downward stroke of said reciprocable member thereby to attract said armature and cause said flexible shaft to urge said tappet towards said second position and allow said tappet to move to said second position when said tappet is unobstructed by said operating member during said downward stroke of said reciprocable member to effect engagement and displacement of said operating member by said tappet on the subsequent upward stroke of said reciprocable member.

2. A system as claimed in claim 1 including abutments mounted on said reciprocable member defining said first and second positions between which said tappet moves, said armature being mounted so that the angle through which it moves upon an upward reciprocating stroke of said reciprocable member is greater than the angle through which said tappet moves from said first to said second position to torsionally strain said torsion member when the tappet is at said first or second positions.

3. A system as claimed in claim 1 including means providing lost motion coupling said spring means to said armature, the spring means also being coupled to said reciprocable member.

4. A system as claimed in claim 3 in which said armature is U-shaped having return bent end portions extending at right angles from the end of the arms, the center portion of the armature being positioned to engage said extension arm and said lost motion coupling means comprises a block mounted on said extension arm and having an aperture therethrough for receiving said center portion of the armature, the aperture having a cross-sectional area larger than that of said center portion of said armature to provide said lost motion.

5. A system as claimed in claim 4 including a coil spring about one return bent end portion of said armature, one end of said coil spring being secured to said one return bent end portion and the other end secured to said torsion member.

6.. A system as claimed in claim 5 in which said torsion member is made of spring steel wire.

7. A system as claimed in claim 4 in which said torsion member and said armature are of integral construction.

8. A system as claimed in claim 1 in which said tappet is wedge-shaped with its base pivotally mounted to said reciprocable member and said tappet is made of plastics material.

9. A system as claimed in claim 8 in which the face of said operating member engageable by the upper surface of said tappet is substantially of the same area as said upper surface.

10. A system as claimed in claim 1 wherein said drive means for said reciprocable member comprises a rotatable shaft, a crank coupling said shaft to said reciprocable member and means for producing a cyclic current having a frequency proportional to the speed of rotation of said shaft, and wherein said electromagnet energization means is responsive to said current to energize said electromagnet during a downward reciprocating stroke of said reciprocable member and deenergize said electromagnet just before the maximum upward reciprocating stroke of said reciprocable member.

11. A system as claimed in claim 1, including a plurality of tappets, a plurality of electromagnets, a plurality of armatures each attractable by a different one of said plurality of electromagnets upon energization thereof and a plurality of torsion members each coupling a different one of said armatures to a corresponding tappet wherein said electromagnet energization means is responsive to the downward reciprocating stroke of said reciprocable member to energize a selected one of said plurality of electromagnets thereby retaining the armature associated with that electromagnet and causing the torsion member coupled to that armature to move the corresponding tappet towards said second position and engage and displace the corresponding operating member on the subsequent upward reciprocating stroke of said reciprocable member.

Claims

1. An operating member selection system comprising: a reciprocable member including drive means coupled thereto for imparting a reciprocating motion to said member in a vertical direction, a tappet pivotally mounted on said reciprocable member, an electromagnet including an armature attractable thereto upon energization thereof, a torsion member comprising a flexible shaft, one end of said flexible shaft being coupled to said armature and the other end of said flexible shaft being coupled to said tappet for urging pivotal movement thereof from a first position to a second position upon movement of said armature towards said electromagnet, an extension arm on said reciprocable member engageable with said armature for effecting movement of said armature towards said electromagnet upon an upward stroke of said reciprocable member, spring means loading said armature into engagement with said extension arm, an operating member positioned for engagement with and displacement by said tappet when said tappet occupies said second position and obstruct pivotal movement of said tappet from said first to said second position during at least a part of the downward stroke of said reciprocable member, and electromagnet energization means responsive to the reciprocating movement of said reciprocable member to energize said electromagnet during at least the latter part of the downward stroke of said reciprocable member thereby to attract said armature and cause said flexible shaft to urge said tappet towards said second position and allow said tappet to move to said second position when said tappet is unobstructed by said operating member during said downward stroke of said reciprocable member to effect engagement and displacement of said operating member by said tappet on the subsequent upward stroke of said reciprocable member.

6. A system as claimed in claim 5 in which said torsion member is made of spring steel wire.