US3241414A

US3241414A - Spring-mounted flexible support for cut-off devices

Info

Publication number: US3241414A
Authority: US
Inventors: Mason James Arthur; Doerman Eryk Stefan
Original assignee: Molins Machine Co Ltd
Current assignee: Molins Machine Co Ltd
Priority date: 1963-07-01
Filing date: 1964-06-16
Publication date: 1966-03-22
Anticipated expiration: 1983-03-22
Also published as: GB1000174A; DE6605359U; DE1295451B

Description

March 22, 1966 so ETAL 3,241,414

SPRING-MCUNTED FLEXIBLE SUPPORT FOR CUT-OFF DEVICES Filed June 16, 1964 i'irevwfls 6 6mm 677A )1 M ym, awM mm United States Patent 3,241,414 SPRING-MOUNTED FLEXIBLE SUPPORT FOR CUT-OFF DEVICES James Arthur Mason and Eryk Stefan Doerman, London, England, assignors to The Molins Organisation Limited, a corporation of Great Britain Filed June 16, 1964, Ser. No. 377,174 Claims priority, application Great Britain, July 1, 1963,

Claims. (Cl. 83-315) This invention concerns improvements relating to supports for reciprocating ledgers used in conjunction with a cut-off mechanism in a continuous rod machine (e.g. a continuous rod cigarette-making machine).

When cutting a continuous rod produced on a continuous rod machine such as a cigarette-making machine, it has been found necessary to support the rod as it is struck by the knife. This support is given by hollow ledgers through which the continuous rod passes. The ledgers are spaced apart sufiiciently to permit the knife blade to pass between them and must be arranged so that they move as nearly as possible at the same linear speed as the rod during the cutting period. It has been the practice for many years to support the ledgers on two leaf springs which were caused to oscillate at the correct frequency by an eccentric drive. The correct frequency is the desired output of the continuous rod machine, measured in the number of units (i.e. cigarettes) to be produced per minute.

The design of the leaf springs has always had to take into account two conditions. The thickness of the spring has had to be sufficient to support the static and dynamic load of the ledgers and their carrier and the live load of the knife striking the rod without permitting any buckling. The second condition is the reverse of the first, since ideally the spring thickness should be reduced as far as possible so as to reduce the bending stress particularly at the top of the spring opposite the eccentric drive. As the operating speed of cigarette-ma king machines in particular have increased it has been found impossible to meet these conditions. Either the thickness of the springs must 'be increased in which case an intolerable stress is placed both on the bearings of the eccentric drive and on the springs, or if the thickness is reduced, buckling takes place, with increased inertial forces causing the springs to fracture. In addition, interference may cause from a harmonic of the natural frequency of the system comprising the springs and the ledger carrier and the operating speed of the cigarette-making machine and this may also lead to fracture.

Consequentially for the high speed machines such as cigarette-making machines it has become necessary to solve this problem and to introduce a system of greater stiffness combined with spring members having a lower bending stress.

According to the present invention there is provided support mechanism for a member adapted for limited side to side movement comprising a parallelogram formed by the said member, a fixed 'base and two rigid support members which are fixed at each of their ends by means of a flexible complex to the fixed base and to the said member.

The support member may be caused to move in the said side to side movement by an eccentrically driven strap joined thereto by a similar flexible complex, and may be provided with means defining a hole through which passes a fixed rod extending towards both sides of the said side to side movement.

The flexible complex may comprise crossed springs.

Further according to the invention there is provided in a continuous rod cigarette-making machine ledger mechanism for use in conjunction with rod cutting mechanism by which a continuously moving cigarette rod is ber form substantially a parallelogram in whatever position they may be.

Apparatus in accordance with the invention will be described by way of example with reference to the accompanying drawings in which:

FIGURE 1 is a front view of ledger support mechanism,

FIGURE 2 is a section along the lines II=II of FIG- URE 1,

FIGURE 3 is an alternative arrangement for an eccentric drive to that shown in FIGURE 1.

Referring to FIGURE 1, a ledger carrier 1 houses two ledgers 2 and 3 and is fixed to a block 4. An eccentric 5 which is driven by means which are not shown has an eccentric strap 6 which is joined to the block 4 by a pin 7. A bar 8, which is fixed to the frame of a cigarettemaking machine 9 passes through a clearance hole 10 in the block 4 and may act as a safety support in case one or other of the ledger carrier supports should fail.

Fixed to the bottom of the block 4 are two angle brackets 11 and 12, attached to which respectively are

springs

13, 14 and 15, 16.

Similar brackets

17 and 18 are fixed to the other ends of

springs

16, 14 and 15, 16 respectively while

rigid support members

19 and 20 are attached to the

brackets

17 and 18 respectively. Attached to a lower portion of the frame of the cigarette-making machine 9 is a fixed base block 21 having bolted to its top corners two

brackets

22 and 23. These brackets'are similar in every way to those already described and are joined by springs 24, 2'5 and 26, 27 respectively to

other brackets

28 and 29 which in their turn are fixed to the

rigid support members

16 and 20.

Reference to FIGURE 2 shows the relationship of the springs. It will be seen that the vertical spring 24 is provided with a hole 30 through which projects the horizontal spring 25 which is narrow compared with the vertical spring 24. The arrangement of the other sets of springs is exactly similar.

The system is a parallelogram the corners of which are the points at which each pair of springs crosses. The two short sides are defined by the block 4 together with the ledger carrier 1 and the fixed base block 2 1 while the two long sides are defined by the

rigid support members

19 and 20. it will be observed that the loading of the parallelogram, i.e. the weight of the ledgers 2 and 3, of the ledger carrier 1 and of the block 4 as well as the live load of the knife striking the cigarette rod, act in the direction of the springs shown vertically in FIG- URE l, i.e.

springs

14, 16, 24 and 26. As the free length of these springs is short in relation to their cross-section the buckling tendency is considerably reduced from what it would be with long springs of the same length as the

rigid support members

19 and 20. Similarly the thrust of the eccentric strap 6 is horizontal when at its maximum with the parallelogram in top dead centre position. This thrust acts directly along the line of the

horizontal springs

13 and 15. By introducing

rigid support members

19 and 20 the natural frequency of the parallelogram is so reduced that interference from the high operating speed of the cigarette-making machine is eliminated.

An alternative embodiment is shown in FIGURE 3 which shows the connecting rod 6 and the block 4, to which are fixed respectively brackets 31 and 32. These brackets 31 and 32 are interconnected by crossed springs 33 and 34, thus providing a flexible linkage between the eccentric drive and the parallelogram. This eliminates the necessity of the pin 7 shown in FIGURE 1.

The operation of the apparatus will now be described. The cut-off knife of the cigarette machine (which is not illustrated) passes between the ledgers 2 and 3. Since the eccentric 5 is geared to the cut-off mechanism and rotates at the same speed as the knife the eccentric strap 6 transmits to the ledger carrier 1 a movement synchronised with that of the knife. The length of the

rigid supports

19 and 20 is arranged so that the speed of the ledger carrier 1 during the time the knife passes between the ledgers 2 and 3 is a mean of the speed of the knife taken in the direction of movement of the continuous cigarette-rod. This mean movement is of course the same as the speed at which the continuous rod is moving and in this way there results a clean cut of the cigarette rod without the knife interfering with either the ledger 2 or the ledger 3.

Since the

rigid supports

19 and 20 are connected to the base block 21 by means of spring complexes as illustrated and described the supports themselves pivot about the point where the springs cross. The length of the

fixed supports

19 and 20 from their pivot points to the centre line of the ledgers 2 and 3 is calculated to be such as to give the necessary component of movement to the ledgers in the direction of movement of the continuous cigarette rod.

What we claim as our invention and desire to secure by Letters Patent is:

1. Support mechanism for a ledger member adapted for limited side to side movement, comprising a fixed base member and two rigid support members which together with said ledger member are formed as a parallelogram, each pair of members being joined by means of a flexible complex, said ledger member being caused to move in said side to side movement by an eccentrically driven strap joined thereto by a similar flexible complex.

2. Support mechanism as claimed in claim 1, wherein the said ledger member is provided with means defining a hole through which passes a fixed rod extending in the general direction of said side to side movement.

3. Support mechanism for a ledger member adapted for limited side to side movement, comprising a fixed base member and two rigid support members which together with said ledger member are formed as a parallelogram, each pair of members being joined by means of a flexible complex, each flexible complex comprising crossed springs.

4. In a continuous rod machine, a ledger machine adapted to hold said continuous rod while being severed into pieces of equal length, a base member, two rigid support members, four flexible complexes each of which fiexs one end of said support members to said base member and said ledger member so that said four members form a parallelogram, an eccentrically driven strap and a fifth flexible complex by which said strap is fixed to said ledger member which is thereby caused to be moved in a side to side movement.

5. In a continuous rod machine, a ledger member adapted to hold said continuous rod while being severed into pieces of equal length, a base member, two rigid support members, four flexible complexes each of which fixes one end of said support members to said base member and said ledger member so that said four members form a parallelogram, and an eccentrically driven strap connected to said ledger member to drive the same in a side to side movement, each flexible complex comprising crossed springs.

References Cited by the Examiner UNITED STATES PATENTS 2,899,044 8/1959 Allen et al. 198-220 WILLIAM W. DYER, JR., Primary Examiner.

L. B. TAYLOR, Assistant Examiner.

Claims

4. IN A CONTINUOUS ROD MACHINE, A LEDGER MACHINE ADAPTED TO HOLD SAID CONTINUOUS ROD WHILE BEING SEVERED INTO PIECES OF EQUAL LENGTH, A BASE MEMBER, TWO RIGID SUPPORT MEMBERS, FOUR FLEXIBLE COMPLEXES EACH OF WHICH FIXES ONE END OF SAID SUPPORT MEMBERS TO SAID BASE MEMBER AND SAID LEDGER MEMBER SO THAT SAID FOUR MEMBERS FORM A PARALLELOGRAM, AN ECCENTRICALLY DRIVEN STRAP AND A FIFTH FLEXIBLE COMPLEX BY WHICH SAID STRAP IS FIXED TO SAID LEDGER MEMBER WHICH IS THEREBY CAUSED TO BE MOVED IN A SIDE TO SIDE MOVEMENT.