US3633718A - Transmission and brake for stopping conveyors - Google Patents

Transmission and brake for stopping conveyors Download PDF

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Publication number
US3633718A
US3633718A US873944A US3633718DA US3633718A US 3633718 A US3633718 A US 3633718A US 873944 A US873944 A US 873944A US 3633718D A US3633718D A US 3633718DA US 3633718 A US3633718 A US 3633718A
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United States
Prior art keywords
speed
signal
driven member
output
generator
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Expired - Lifetime
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US873944A
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English (en)
Inventor
Rudolf Wanner
Berthold Mader
Theodor Mayr
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Boewe Boehler and Weber KG
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Boewe Boehler and Weber KG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
    • B23D33/00—Accessories for shearing machines or shearing devices
    • B23D33/006—Accessories for shearing machines or shearing devices for obtaining pieces of a predetermined length, e.g. control arrangements

Definitions

  • a pulse counter excited by the drive shaft measures a braking interval in the final phase of each operating cycle and, at the inception of that interval, triggers a generator of progressively increasing voltage whose output causes the switchover upon reaching a reference value registered in a storage circuit.
  • the stored reference voltage is either increased or reduced to delay or advance the switchover point to a predetermined instant slightly preceding the end of the H cycle.
  • Our present invention relates to a system for intermittently driving a load such as a movable machine part, e.g., a conveyor serving to feed an elongate web or a succession of sheets of paper or the like to a cutter, printer or other processing stage, in repetitive operating cycles each including a highspeed phase and a low-speed phase.
  • a load such as a movable machine part, e.g., a conveyor serving to feed an elongate web or a succession of sheets of paper or the like to a cutter, printer or other processing stage, in repetitive operating cycles each including a highspeed phase and a low-speed phase.
  • the general object of our present invention is to provide an improved method of and means for so operating a machine of this type that the intermittently movable part thereof is always decelerated at a safe distance from its terminal position but so close to that position that the average operating speed remains high.
  • a more specific object is to provide a system of this character particularly adapted for the control of an intermittently and unidirectionally rotating drive shaft, e.g., as used to operate a conveyor of a paper-cutting machine.
  • a predetermined length of travel e.g., in terms of revolutions of a drive shaft
  • this length being somewhat less than the total displacement of the load during an operating cycle; the remainder of the cycle, or at least the major portion of the remainder, constitutes a braking interval during which the load speed is progressively reduced from a relatively high level to a relatively low level.
  • the load is decelerated to a relatively low speed level, preferably by switching its drive from a high-speed input to a low-speed input; after the load has reached its lower speed level, the duration of its movement at that speed to its terminal position (or to a position slightly preceding same) is ascertained and is used to increase or decrease the reference magnitude so as to delay or advance the start of the slowdown in the next cycle in a manner maintaining the end of the deceleration step close to the terminal position, i.e., keeping the time of low-speed travel as short as possible.
  • a progressively changing variable e.g., a voltage
  • the length of travel at high speed to an intermediate point and at low speed to a terminal point may be conveniently measured with the aid of path-length-measuring means comprising a pulse counter excited by a pulse generator driven by the shaft.
  • the pulse counter on reaching a first count denoting the start of the braking interval, emits a signal which, according to a preferred embodiment, triggers speedsensing means including a generator of a sawtooth voltage whose rising flank (of either polarity) progressively approaches a stored potential until a comparator indicates the equality of the two voltage levels.
  • the drive shaft heretofore coupled to a high-speed input shaft for entrainment thereby, is decoupled from that input shaft and is coupled through a slipping clutch to a low-speed input shaft so as gradually to approach the velocity of the latter.
  • this velocity or a critical velocity slightly higher than that of the low-speed input shaft
  • the counter emits a second signal indicating the end of the braking interval; in this case, the device (e.g., a capacitance) storing the reference potential is further charged during the span between the end of deceleration and the end of the braking interval so that the magnitude of the reference potential is increased.
  • the start of deceleration is delayed so as to foreshorten the time of low-speed travel. If, however, the end of deceleration as determined by the comparator output occurs at an instant beyond the braking interval (whose end, therefore, must precede the arrival of the load in its terminal position), the storage device is partly discharged during the period between the end of the braking interval and the reduction of the shaft speed to the critical level so as to lower the reference potential whereby the start of deceleration is advanced in the following cycle.
  • the rates of charge and discharge should be so chosen that the positive or negative increment per cycle of the time elapsed between the start of the braking interval and the beginning of deceleration amounts to only a fraction of that braking interval, the system being thus able to compensate for gradual fluctuations in the length of an operating cycle while maintaining the end of deceleration close to the stopping point.
  • FIG. 1 is a somewhat diagrammatic layout of a control system according to the invention.
  • FIG. 2 is a set of graphs relating to the operation of the system of FIG. 1.
  • a motor M representing a continuously operable drive means drives via a transmission 1 a pair of shafts 2 and 3, shaft 3 rotating at a high speed v whereas shaft 2 rotates at a considerably lower speed v Shafts 2 and 3 serve as alternate input members for a driven shaft 5 which can be selectively coupled to either of these input shafts through a switching mechanism 4 including yieldable coupling means shown as a pair of slipping clutches which are altemately operable to accelerate the shaft 5 to speed level V and to decelerate it to speed level v
  • a machine part to be intermittently advanced, here shown as a conveyor 6, is coupled with shaft 5 for entraining a workpiece 8, such as a paper web, in the direction of an arrow 7.
  • Conveyor 6 may be part of a paper-cutting machine having means for slicing the web 8 whenever the conveyor 6 comes to a halt.
  • the conveyor can be positively arrested by a solenoid 10 which drives a pawl 11 into engagement with a ratchet 9 on shaft 5.
  • a toothed wheel 12 moving in the field of a magnetic pickup head 13 which generates a pulse upon the passage of each tooth.
  • These pulses are delivered to a counter 14 having three outputs Bl, BG and VE.
  • the pulses registered in counter 14 are further transmitted to a sawtooth-wave generator 15 where they trigger successive voltage cycles.
  • a speed-sensing means constituted by a threshold sensor 16 compares the stepped voltage from generator 15 with a fixed but preferably adjustable voltage level 17 (see FIG.
  • AND-gate 20 is connected to the output BI of pulse counter 14, in parallel with an input of a further AND-gate 19 having an inverting second input connected to the set output of another flip-flop 23.
  • the second input of AND-gate 21 is connected to the output B0 of pulse counter 14 whose output VE drives the resetting input of flip-flop 23 and, in parallel therewith, the solenoid 10.
  • coincidence gates 20 and 21 are tied to a charging input and a discharging input respectively, of a storage device C which may include a conventional resistance/capacitance network. These two inputs, when energized, cause a gradual and preferably linear change in the output voltage of device C which remains constant if neither of these inputs is energized.
  • a further input 29 serves for a rapid resetting of the device C to zero when manually connected to a voltage source not shown. Charging and discharging along slightly nonlineare.g., exponentialcharacteristics may be tolerated.
  • Another sawtooth-voltage generator H is triggerable by an output signal from AND-gate 19 to produce a rising voltage, here assumed to be positive, and to return to zero whenever the input signal disappears.
  • the outputs of generator H and storage device C are applied to opposite inputs of a comparator 22 which delivers an output signal to the setting input of flip-flop 23 as soon as the generator voltage reaches the output potential of unit C.
  • the set output of flip-flop 23, aside from being fed to the inverting input of AND-gate 19 as described above, is also transmitted to the resetting input of flip-flop 18 and to a relay 24 which, when energized, actuates switchover means in the form of a solenoid 25 for reversing the switching mechanism 4 as diagrammatically indicated by an arrow 26.
  • FIG. 2 shows in graph (a) the velocity v of shaft and in graph (b) the voltages V in the outputs of circuits 14, H and C, all plotted against time t in the course of a complete operating cycle of the system.
  • a predetermined pulse count P signifies the arrival of the load (i.e., web 8) in a predetermined position close enough to the limit of its stroke to allow deceleration of shaft 5 to begin.
  • This pulse count P occurs at a time t whose distance from starting time 1, may be subject to variation.
  • Time t marks the beginning of a braking interval characterized by the presence of a first signal voltage on counter output B], as illustrated in FIG.
  • the time interval T between instants t and 1 depends on the charge stored in circuit C, i.e., on the voltage level V applied to the right-hand input of comparator 22.
  • the voltage V concurrently applied to the left-hand input of this comparator constitutes a progressively changing variable which rises from zero at instant t and reaches the level V at instant t, to start a time interval T, during which the deceleration of shaft 5 takes place.
  • the output of comparator 22 sets the flip-flop 23 with consequent blocking of AND-gate 19 to restore the sawtooth generator H to zero, resetting of flip-flop l8 and energization of relay 24 to shift the mechanical switch 25.
  • threshold sensor 16 responds and sets the flip-flop 18 whereby AND-gate 20 is unblocked in view of the presence of voltage from counter output BI on its other input. This action charges the storage device C to raise its output voltage to a new level V during an interval T, ending at instant t i.e., with the deenergization of counter-output BI. Since flip-flop I8 is set, the energization of-output 80 has no effect upon the blocked AND-gate 21 and does not cause any change in the charge stored in device C.
  • the storage circuit C may be discharged via its reset input 29 in order to find its new level consistent with the altered operating conditions.
  • comparator 22 responds immediately to the rising output voltage of generator H so that the braking interval starts substantially at time t It will be noted that this braking interval has been chosen considerably larger than the time T, required for deceleration and that the rate of change of AV or AV" of reference potential V from one cycle to the other, is relatively small so that the shift AT of the deceleration period from its initial position at the beginning of the braking interval toward its ultimate position at the end of that interval will normally occur over a succession of several cycles. This guards against overreaction to changing operating conditions which might endanger the safety of operation.
  • a system for intermittently driving a load in repetitive operating cycles comprising:
  • continuously operable drive means switchable between a high and a low speed level, said drive means being operatively connected with said driven member and including a yieldable coupling effective at least at said low speed level whereby said driven member is progressively decelerated upon a switching to said low speed level and is arrestable on being entrained at low speed;
  • switchover means for said drive means having a high-speed and a low-speed position
  • path-length-measuring means responsive to the displacement of said driven member for emitting a first signal upon the attainment of a predetermined intennediate point of a working stroke and for emitting a second signal upon the approach of a terminal point of said working stroke;
  • comparator means connected to said generator means and to said source for determining the arrival of said variable at a value bearing a predetermined relationship with said reference magnitude, said comparator means on ascertaining said relationship providing an output signal controlling said switchover means for changing same to said low-speed position whereby said driven member is subjected to progressive deceleration;
  • speed-sensing means controlled by said driven member for determining the arrival thereof at a critical speed close to said low speed level
  • timing means jointly controlled by said speed-sensing means and said path-length-measuring means for determining the relative time position of the instant of arrival at said critical speed and the emission of said second signal, said source being responsive to said timing means for altering said reference magnitude in a sense shifting the point of change of said switchover means during a subsequent operating cycle to terminate the deceleration of said driven member at an instant closer to the emission of said second signal;
  • path-lengthmeasuring means comprises a pulse generator and a pulse counter receiving the output of said pulse generator.
  • said speed-sensing means comprises a sawtooth-voltage generator triggerable by the output of said pulse generator and threshold means for comparing the output of said sawtooth-voltage generator with a predetermined amplitude level.
  • said generator means comprises a voltage generator with a substantially linearly varying output voltage, said source being a storage circuit for an electrical charge.
  • timing means comprises a bistable element settable by said speed-sensing means and resettable by said comparator means, a first coincidence circuit jointly controlled by said bistable element and said path-length-measuring means for causing a progressive increase in the charge of said storage circuit during a period beginning with said output signal and ending with said second signal, upon said output signal preceding said second signal, and a second coincidence circuit jointly controlled by said bistable element and by said path-length-measuring means for causing a progressive decrease in said charge during a period beginning with said second signal and ending with said output signal, upon said second signal preceding said output signal.
  • said first and second coincidence circuits comprise a pair of AND-gates with respective inputs connected in parallel to an output of said bistable element, one of said inputs including an inverter.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Direct Current Motors (AREA)
  • Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)
  • Control Of Conveyors (AREA)
US873944A 1968-11-06 1969-11-04 Transmission and brake for stopping conveyors Expired - Lifetime US3633718A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19681807364 DE1807364B1 (de) 1968-11-06 1968-11-06 Verfahren und Anordnungen zum Abbremsen und Anhalten einer Maschine

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US3633718A true US3633718A (en) 1972-01-11

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US873944A Expired - Lifetime US3633718A (en) 1968-11-06 1969-11-04 Transmission and brake for stopping conveyors

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US (1) US3633718A (fr)
DE (1) DE1807364B1 (fr)
FR (1) FR2022700A1 (fr)
GB (1) GB1281576A (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3771643A (en) * 1971-04-14 1973-11-13 Smidth & Co As F L Start-reversing vertical screw elevator
DE2534565A1 (de) * 1975-06-12 1976-12-16 Cetim Sa Vorrichtung zum selbsttaetigen schalten der uebersetzungsstufen eines getriebes
US4022307A (en) * 1974-11-14 1977-05-10 Regie Nationale Des Usines Renault Device for driving a transfer beam
US4106390A (en) * 1975-12-01 1978-08-15 Kuroda Seiko Co., Ltd. Pneumatic linear actuator
US4339984A (en) * 1973-05-29 1982-07-20 G. H. Pfaff Pietzsch Industrieroboter Drive, particularly for an industrial manipulator
US5346046A (en) * 1991-04-23 1994-09-13 Peters John M Automation control with improved operator/system interface
US5413212A (en) * 1994-04-18 1995-05-09 Pitney Bowes Inc. System and method for automatic correction of pusher position after power loss
US5941359A (en) * 1995-02-15 1999-08-24 Printe, Co., Ltd. Positioning apparatus
US6446791B1 (en) * 1999-02-15 2002-09-10 Siemens Aktiengesellschaft Feeder for taped SMD components

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3823304A1 (de) * 1988-07-09 1990-01-11 Danfoss As Verfahren und schaltung zur geschwindigkeitssteuerung eines durch einen antrieb bewegbaren objekts

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3157261A (en) * 1961-02-10 1964-11-17 Necchi Spa Programmed start and stop for a machine such as a sewing machine
US3352396A (en) * 1965-06-22 1967-11-14 Gen Time Corp Drive and stop control for a driven machine
US3420347A (en) * 1966-09-20 1969-01-07 Warner Electric Brake & Clutch System for rapid and precise positioning

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3157261A (en) * 1961-02-10 1964-11-17 Necchi Spa Programmed start and stop for a machine such as a sewing machine
US3352396A (en) * 1965-06-22 1967-11-14 Gen Time Corp Drive and stop control for a driven machine
US3420347A (en) * 1966-09-20 1969-01-07 Warner Electric Brake & Clutch System for rapid and precise positioning

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3771643A (en) * 1971-04-14 1973-11-13 Smidth & Co As F L Start-reversing vertical screw elevator
US4339984A (en) * 1973-05-29 1982-07-20 G. H. Pfaff Pietzsch Industrieroboter Drive, particularly for an industrial manipulator
US4022307A (en) * 1974-11-14 1977-05-10 Regie Nationale Des Usines Renault Device for driving a transfer beam
DE2534565A1 (de) * 1975-06-12 1976-12-16 Cetim Sa Vorrichtung zum selbsttaetigen schalten der uebersetzungsstufen eines getriebes
US4106390A (en) * 1975-12-01 1978-08-15 Kuroda Seiko Co., Ltd. Pneumatic linear actuator
US5346046A (en) * 1991-04-23 1994-09-13 Peters John M Automation control with improved operator/system interface
US5413212A (en) * 1994-04-18 1995-05-09 Pitney Bowes Inc. System and method for automatic correction of pusher position after power loss
US5941359A (en) * 1995-02-15 1999-08-24 Printe, Co., Ltd. Positioning apparatus
US6446791B1 (en) * 1999-02-15 2002-09-10 Siemens Aktiengesellschaft Feeder for taped SMD components

Also Published As

Publication number Publication date
DE1807364B1 (de) 1970-10-29
FR2022700A1 (fr) 1970-08-07
GB1281576A (en) 1972-07-12

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