GB1577314A

GB1577314A - Spools

Info

Publication number: GB1577314A
Application number: GB4320376A
Authority: GB
Original assignee: RIGBY Ltd R
Current assignee: RIGBY Ltd R
Priority date: 1975-12-03
Filing date: 1977-02-03
Publication date: 1980-10-22

Description

(54) SPOOLS (71) We, ROBERT RIGBY LIMITED, a British Company, of Premier Works, Northington Street, London WC1N 2JH, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to spools, and in particular to spools on which films or tapes are wound.

One type of known spool on which, for example, film or tape may be wound comprises a pair of circular cheek plates, or wire cheeks, and a central core having means, such as a non-circular hole or a circular hole having a keyway, for mounting the spool fast on an axial drive shaft which rotates the spool so as to wind on the film or tape. If the film or tape is slack, the drive shaft causes the spool to take up this slack quickly, imparting considerable tensional force to the film or tape. This process, which is called "snatching", often results in film or tape breakage.

Another problem which arises with known spools occurs in certain film or tape transport mechanisms which have a pair of shafts, each of which holds two or more spools, one of the shafts being rotated to transfer the film or tape from the spool on the other shaft. The rate at which the film or tape should be transported depends upon the rotational speed of the drive shaft and the diameter of the film wound on the spool which is being driven. If this diameter varies from spool to spool, as often occurs, the mechanism will attempt to transfer films or tapes at different speeds. However, the spools on each shaft must be rotated in unison. This means that these transport mechanisms cannot be used unless the diameters of the film or tape wound on the various spools of each shaft are equal.

The present invention provides a spool for receiving a flim or tape comprising a central core which is adapted for non-rotatable connection to a driving shaft, and an outer core, around the central core, which is intended to receive a film or tape to be wound, the central core engaging the outer core either directly or through a separate friction member, and a biassing means to cause the said engagement of the central and outer cores the arrangement being such that the central core is driven and the drive is transmitted to the outer code by the direct or indirect frictional engagement of the central core with the outer core until a predetermined torque exerted by the driving shaft on the spool is reached, when the central core slips relatively to the outer core.

Thus, when slack is taken up, and snatching occurs, the force on the film or tape is limited to the frictional force between the outer core and the central core, any greater force causing slip, i.e., relative movement of the outer and the central cores. Therefore, no film breakage occurs.

A friction member may be mounted between the cores, non-rotatably connected to one of the cores and resiliently gripping the other core so that there is sufficient friction between this other core and the friction member to transmit rotational drive forces between the cores.

In another embodiment, the outer core has at least two circumferential parts which are biased together so that the outer core resiliently grips the central core, thus ensuring that there will be sufficient friction between the cores to enable one of the cores to drive the other.

Alternatively, the central core, rather than the outer core, may be formed in at least two circumferential parts. These parts are biased apart so that the central core resiliently grips the outer core in order to obtain the desired function of the spool.

The outer core may have a channel extending around its inner circumference and which is sized so as to receive the central core, thus holding the central core against axial displacement. Alternatively, the central core may have a channel extending around its outer circumference to receive the outer core.

The spool may have a pair of circular cheek plates (or wire cheeks) which are fixed to either the central core or the outer core.

Spools in accordance with the invention may be used on transport mechanisms having a pair of shafts, each for carrying more than one spool, even when the films or tapes wound on the spools are of different diameter.

Relative movement between central cores and outer cores allows the outer cores of spools on the same shaft to rotate at different speeds, and thus to take up or release film or tape at the correct speed, depending upon the diameter of the film or tape wound on the spools.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a plan view of one embodiment of a spool in accordance with the invention.

Figure 2 is a view along X-X of Figure 1, Figure 3 is a plan view of a second embodiment of a spool in accordance with the invention, Figure 4 is an elevation of the cores of a further embodiment of a spool in accordance with the invention, Figure 5 is a side view of the cores of Figure 4, Figure 6 is an exploded view showing the way in which the cores of Figure 4 are fitted together, Figure 7 is an elevation of the cores of another embodiment of a spool in accordance with the invention Figure 8 is a side view of the cores of Figure 7, and Figure 9 is a partly exploded view showing the way in which the cores of Figure 7 are fitted together.

Figure 10 is a side view of the transport mechanism having a plurality of spools in accordance with the invention.

Figure 11 is a plan view of the transport mechanism of Figure 10.

Referring to Figures 1 and 2, a spool generally indicated at 2 comprises a pair of circular cheek plates 4, in the centre of, and between, which is a central core 6, which is fixed to the cheek plates 4. The central core 6 has a square aperture 8 for receiving a drive shaft 10. Surrounding the central core 6 is an outer core 12, on which tape indicated at 14 is to be wound.

In an alternative embodiment, the cheek plates 4 may be fixed to the outer core 12 rather than the central core 6.

The central core 6 has a circumferential groove 16, in which is situated a member 18. The member 18 has two slots 20, in which the opposite ends of a tension spring 22 are located. The spring 22 extends around the circumferential groove 16, and holds the arcuate surface 24 of member 18 in frictional engagement with central core 6.

The member 18 is provided with a member in the form of a drive pin 26, which locates in a recess 28 provided in outer core 12. The outer core 12 also has a slot 30 for receiving and retaining the end of tape 14.

Operation of the spool 2 is as follows. The drive shaft 10 imparts rotational movement to central core 6. Because of the frictional engagement of member 18 with central core 6, this member is also rotated. The drive pin 26, which is fixed to member 18, then imparts this rotation to outer core 12, causing tape 14 to be wound on the spool 2. If there is slack in tape 14, this slack will be taken up quickly resulting in snatching of the tape. If the tension in the tape 14, when this snatching occurs, is large enough, outer core 12 and member 18 will cease to rotate at the same speed as central core 6, the frictional force occurring between surface 24 of member 18 and central core 6 being overcome.

In another embodiment, the frictional member 18 may have a pin for location in the central core 6 so that the member 18 is non-rotatably mounted on the central core, and a compression spring for resiliently gripping the outer core 12. In a further embodiment the member 18 may be arranged resiliently to grip both cores.

Referring now to Figure 3, the spool 32 has cheek plates 34 and a central core 36, in which is provided a square aperture 38 for receiving a drive shaft (not shown).

The central core 36 is surrounded by an outer core comprising two arcuate members or elements 40. The elements 40 are held in frictional engagement with the central core 36 by means of a tension spring 42, and a threaded rod 44. The threaded rod has a right hand thread at one end and a left hand thread at the other end, so that rotational movement of the rod by means of nut 46 causes the rod to screw into the ends of elements 40 so as to pull the ends together. It will be appreciated that instead of this arrangement, the spring may be replaced by another threaded rod, or vice versa. One of the elements 40 is provided with a slot 48 for receiving and retaining the end of tape 50.

Operation of this spool is similar to that of the spool show in Figures 1 and 2 in that the friction caused by the elements 40 resiliently gripping the central core 36 is sufficient to transmit rotational drive forces between the cores until a predetermined torque is reached, which torque is determined by the force with which the elements 40 are biased together, when the cores slip relative to each other.

Referring to Figures 4 to 6, the central part 100 of another spool of the present invention comprises a central core 102 and an outer core 104, the outer core 104 being formed of two semi-circular parts 106 and 108.

The central core 102 has a central aperture 110 for receiving a shaft (not shown). A keyway 112 is formed at one point on the edge of the aperture 110 so as to ensure that the central core 102 is non-rotatably mounted with respect to the shaft when the core is mounted on the shaft with the key (not shown) of the shaft in the keyway 112.

The outer surface of the central core 102 is cylindrical and the parts 106 and 108 of the outer core 104 have channels 114 and 116 extending around their inner circumference and of such a shape as to receive the outer surface of the central core 102.

The parts 106 and 108 of the outer core 104 also have channels 118 and 120 extending around the circumference of their outer surface. These channels 118 and 120 receive a spring, or a number of inter-linked springs, 122, extending completely around the outer core 104.

The spring 122 acts to force the two parts 106 and 108 of the outer core 104 together, and, because the diameter of the central core 102 is slightly larger than the inner diameter between the bottoms of the channels 114 and 116 when the two parts 106 and 108 are biased towards one another, this causes the outer core 104 resiliently to grip the inner core 102.

A pair of circular cheek plates (not shown) are fixed to the outer core 104 with their axes coincident with that of the cores. A film or tape may be wound on to the outer core 104 between the cheek plates. The outer core 104 may be provided with a slot (not shown) to retain the end of the film or tape.

The film or tape is wound on by rotating the shaft extending through the aperture 110 of the central core 102. The friction between the outer surface of the central core 102 and the bottoms of the channels 114 ard 116 is sufficient to cause the central core 102 and the bottoms of the channels which are normally present in the operation of such spools. However, if a greater than normal torque occurs such as may happen when "snatching" takes place or when the shaft is rotating at a faster speed than is allowed by the rate at which the film or tape is permitted to be wound, the central core 102 will slip with respect to the outer core 104, so that the film or tape will not break, as in the embodiment shown in Figures 1 to 3.

The cores shown in Figures 7 to 9 are generally similar to those shown in Figures 4 to 6, and like parts are given like reference numerals. In this case, however, the outer core 104 is formed in a single, ring-shaped part. The inner core 102 is formed of two semi-circular parts 124 and 126. These parts 124 and 126 are biased apart by four compression springs 128, two at each end of each part, which are retained in recesses 130 in the ends of the parts. The outer surfaces of the parts 124 and 126 are received in channels 114 and 116 on the inner surface of the outer core 104. It will thus be appreciated that the force of the springs 128 tends to push the parts 124 and 126 apart, so that the inner core 102 resiliently grips the inner surface of the outer core 104.

A pair of cheek plates are fixed coaxially to the sides of the outer core 104.A film or tape may then be wound on the outer core, the end of the film or tape being fixed in a slot 132 provided for this purpose.

In all of the above embodiments of spools, the outer diameter of the outer core may be made equal to the standard hub size of known spools, and similarly the shaft receiving aperture may also have a size and shape corresponding to those of standard known spools.

Referring now to Figures 10 and 11, the transport mechanism shown here has two shafts 52 and 54. The transport mechanism has drive means to drive at least one of the shafts. On each of shafts 52 and 54 are nonrotatably mounted the central cores of three spools shown at 56 and 58 respectively. Each spool is constructed in accordance with the invention, and may be one of the types described above. In use, the shaft 52 rotates anti-clockwise so as to wind film from spools 58 to spools 56. It will be appreciated that the transport of film can be reversed by imparting a clockwise drive to shaft 54 and removing the drive from shaft 52.

It will be observed that the diameter of the film wound on each of the spools 56 is different, and this applies also to the diameter of the films wound on spools 58. Accordingly, in order to transport the film to the spools on shaft 52, the relative speeds of the outer cores of the spools 56, and those of the outer cores of the spools 58, will vary in accordance with the diameter of the film on the spool.

This relative movement is possible by virtue of the fact that outer cores of spools on each shaft are frictionally rotatable with respect to the central cores, which central cores are non-rotatable with respect to each other.

WHAT WE CLAIM IS: 1. A spool for receiving a film or tape comprising a central core which is adapted for non-rotatable connection to a driving shaft, and an outer core, around the central core, which is intended to receive a film or tape to be wound, the central core engaging the outer core either directly or through a separate friction member, and a biassing means to cause the said engagement of the central and outer cores the arrangement being such that the central core is driven and the drive is transmitted to the outer core by

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. outer core 104, the outer core 104 being formed of two semi-circular parts 106 and 108. The central core 102 has a central aperture 110 for receiving a shaft (not shown). A keyway 112 is formed at one point on the edge of the aperture 110 so as to ensure that the central core 102 is non-rotatably mounted with respect to the shaft when the core is mounted on the shaft with the key (not shown) of the shaft in the keyway 112. The outer surface of the central core 102 is cylindrical and the parts 106 and 108 of the outer core 104 have channels 114 and 116 extending around their inner circumference and of such a shape as to receive the outer surface of the central core 102. The parts 106 and 108 of the outer core 104 also have channels 118 and 120 extending around the circumference of their outer surface. These channels 118 and 120 receive a spring, or a number of inter-linked springs, 122, extending completely around the outer core 104. The spring 122 acts to force the two parts 106 and 108 of the outer core 104 together, and, because the diameter of the central core 102 is slightly larger than the inner diameter between the bottoms of the channels 114 and 116 when the two parts 106 and 108 are biased towards one another, this causes the outer core 104 resiliently to grip the inner core 102. A pair of circular cheek plates (not shown) are fixed to the outer core 104 with their axes coincident with that of the cores. A film or tape may be wound on to the outer core 104 between the cheek plates. The outer core 104 may be provided with a slot (not shown) to retain the end of the film or tape. The film or tape is wound on by rotating the shaft extending through the aperture 110 of the central core 102. The friction between the outer surface of the central core 102 and the bottoms of the channels 114 ard 116 is sufficient to cause the central core 102 and the bottoms of the channels which are normally present in the operation of such spools. However, if a greater than normal torque occurs such as may happen when "snatching" takes place or when the shaft is rotating at a faster speed than is allowed by the rate at which the film or tape is permitted to be wound, the central core 102 will slip with respect to the outer core 104, so that the film or tape will not break, as in the embodiment shown in Figures 1 to 3. The cores shown in Figures 7 to 9 are generally similar to those shown in Figures 4 to 6, and like parts are given like reference numerals. In this case, however, the outer core 104 is formed in a single, ring-shaped part. The inner core 102 is formed of two semi-circular parts 124 and 126. These parts 124 and 126 are biased apart by four compression springs 128, two at each end of each part, which are retained in recesses 130 in the ends of the parts. The outer surfaces of the parts 124 and 126 are received in channels 114 and 116 on the inner surface of the outer core 104. It will thus be appreciated that the force of the springs 128 tends to push the parts 124 and 126 apart, so that the inner core 102 resiliently grips the inner surface of the outer core 104. A pair of cheek plates are fixed coaxially to the sides of the outer core 104.A film or tape may then be wound on the outer core, the end of the film or tape being fixed in a slot 132 provided for this purpose. In all of the above embodiments of spools, the outer diameter of the outer core may be made equal to the standard hub size of known spools, and similarly the shaft receiving aperture may also have a size and shape corresponding to those of standard known spools. Referring now to Figures 10 and 11, the transport mechanism shown here has two shafts 52 and 54. The transport mechanism has drive means to drive at least one of the shafts. On each of shafts 52 and 54 are nonrotatably mounted the central cores of three spools shown at 56 and 58 respectively. Each spool is constructed in accordance with the invention, and may be one of the types described above. In use, the shaft 52 rotates anti-clockwise so as to wind film from spools 58 to spools 56. It will be appreciated that the transport of film can be reversed by imparting a clockwise drive to shaft 54 and removing the drive from shaft 52. It will be observed that the diameter of the film wound on each of the spools 56 is different, and this applies also to the diameter of the films wound on spools 58. Accordingly, in order to transport the film to the spools on shaft 52, the relative speeds of the outer cores of the spools 56, and those of the outer cores of the spools 58, will vary in accordance with the diameter of the film on the spool. This relative movement is possible by virtue of the fact that outer cores of spools on each shaft are frictionally rotatable with respect to the central cores, which central cores are non-rotatable with respect to each other. WHAT WE CLAIM IS:

1. A spool for receiving a film or tape comprising a central core which is adapted for non-rotatable connection to a driving shaft, and an outer core, around the central core, which is intended to receive a film or tape to be wound, the central core engaging the outer core either directly or through a separate friction member, and a biassing means to cause the said engagement of the central and outer cores the arrangement being such that the central core is driven and the drive is transmitted to the outer core by

the direct or indirect frictional engagement of the central core with the outer core until a predetermined torque exerted by the driving shaft on the spool is reached, when the central core slips relatively to the outer core.

2. A spool as claimed in Claim 1, wherein the cores engage each other via a friction member, the friction member being nonrotatably mounted to one of the cores and resiliently gripping the other core.

3. A spool as claimed in Claim 2, wherein the friction member is provided with a member which locates in a recess in the said one of the cores.

4. A spool as claimed in Claim 2 or 3, wherein the friction member is non-rotatably connected to the outer core, and has a surface which engages the central core, a tension spring being provided, extending around the central core and fixed at both ends to the friction member so as firmly to hold the surface against the central core.

5. A spool as claimed in Claim 1, wherein one of the cores is formed in more than one part, biasing means being provided to cause the parts resiliently to grip the other core.

6. A spool as claimed in Claim 5, wherein the outer core is formed in two parts, the biasing means comprises a tension spring arranged to bias the parts together.

7. A spool as claimed in Claim 6, wherein each of the parts has a screw-threaded hole at one end thereof, a rod having a screwthread at each end being adapted to engage the holes in both members in such a manner that rotation of the rod causes the parts to move together.

8. A spool as claimed in Claim 5 wherein the central core is formed in two parts, the biasing means including a compression spring arranged to bias the parts away from each other.

9. A spool as claimed in Claim 8 wherein a pair of compression springs is provided between each pair of adjacent ends of the parts.

10. A spool as claimed in any one of Claims 5 to 9 wherein the outer core has a channel extending around its inner circumference within which the central core is situated, the channel thereby retaining the central core against axial displacement.

11. A spool as claimed in any one of Claims 5 to 9 wherein the outer core is retained against axial displacement relative to the central core by a channel extending around the outer circumference of the central core.

12. A spool as claimed in any preceding claim having a pair of cheek plates, in the centre of and between which are mounted the cores, the cheek plates being fixed to one of the cores.

13. A spool substantially as herein described with reference to Figures 1 and 2, or Figure 3, or Figures 4, 5 and 6 or Figures 7, 8 and 9 of the accompanying drawings.

14. A transport mechanism having two shafts and drive means rotationally to drive at least one of the shafts, at least two spools being mounted on each shaft, at least one of the spools being of the type claimed in any preceding claim so that films may be transported from the spools on one of the shafts to those on the other shaft at different respective speeds.

15. A transport mechanism substantially as herein described with reference to Figures 10 and 11 of the accompanying drawings.