Claims:
What is claimed is
1. A bobbin changer for spindle type spinning machines comprising:
2. A bobbin changer according to claim 1, wherein the said common plane is a horizontal plane, and the loading and unloading stations are located, respectively, at opposite ends of the machine.
3. The bobbin changer claimed in claim 2, further comprising a second mechanism including means for moving the endless-belt support horizontally, and perpendicularly to the direction in which the spindle bank extends, between a near position -- in which the inner run is in the vertical plane of the spindle bank -- and a remote position -- in which the inner run is in a vertical plane remote from the said vertical plane of the spindle bank -- the loading station and unloading station being on the path of the endless belt when the support thereof is in such remote position.
4. The bobbin changer claimed in claim 3, wherein the second mechanism is an actuator mechanism comprising a number of screw actuators whose respective rods are connected to the bottom frame, the screw of each such actuator cooperating with a tapped nut in engagement with a driving gear secured to a drive shaft extending over the whole length of the bottom frame and drivable to either hand of rotation by a motor-reducer set.
5. The bobbin changer claimed in claim 2, wherein each gripping device comprises a hook whose bottom part has two horizontal arms, and each bobbin has at its top end a cylindrical stud which is coaxial of the bobbin and whose bottom diameter is less than the separation between the two arms of the gripping device, the stud terminating in a circular head whose diameter is greater than the separation between the two arms of the gripping device, each gripping device being so borne by the endless belt that the horizontal arms of the gripping device present their open part when the endless belt moves in the bobbin-engaging direction.
6. The bobbin changer claimed in claim 2, wherein the loading station comprises a moving element and means for moving the moving element near the endless belt while engaging empty bobbins and away from the endless belt upon the completion of such engaging operations.
7. The bobbin changer claimed in claim 6, wherein the moving element comprises a waiting spout including means for holding a number of empty bobbins disposed vertically with their cylindrical studs at the top, and means for bringing the spout into such a position during engagement of the empty bobbins that the cylindrical stud of that particular empty bobbin which is near the spout aperture is on the path of the gripping devices.
8. The bobbin changer claimed in claim 2, wherein the unloading station comprises a moving element and means for moving the moving element near the endless belt during the operations of disengaging full bobbins and away from the endless belt upon the completion of such disengaging operations.
9. The bobbin changer claimed in claim 8, wherein the said moving element comprises a stop finger means, operable when near the endless belt, for stopping the movement of each full bobbin seriatim and disengaging the same by disengagement of the cylindrical stud from the arms of each gripping device.
10. The bobbin changer claimed in claim 2, wherein the first mechanism is a parallelogram linkage comprising a number of long rods each articulated to the endless-belt support and to a member movable parallel thereto, each long rod being articulated at its center to a short rod whose length is half the length of the long rod, the short rod being articulated to a bottom frame, the moving parts comprising a tapped portion cooperating with a worm extending over the whole length of the machine and drivable to either hand by a motor-reducer set.
11. The bobbin changer claimed in claim 2, including centering means for immobilizing without locking each empty bobbin hung on the corresponding gripping device above the corresponding spindle.
12. The bobbin changer claimed in claim 11, wherein the centering means comprise: fork-like elements having two horizontal arms and a permanent magnet secured therebetween, each such element being disposed above the corresponding spindle and rings which are made of a ferro-magnetic substance and which are rigidly secured to the bottom part of each bobbin.
13. The bobbin changer claimed in claim 11, wherein the centering means comprise: fork-like elements having two horizontal arms, each such element being disposed above the corresponding spindle; and a closed duct which is made of a deformable substance and which extends over the whole length of the spindle bank and which is retained by a rigid support, the latter being rigidly secured to the endless-belt support, the duct being disposed on the side where the fork-like elements are open and being so disposed relatively to the endless-belt inner run that, when the pressure in the duct is the ambient pressure, such duct does not touch the empty or full bobbins hung on the gripping devices of the endless-belt bottom run, but when a pressure above ambient pressure exists in the duct, the duct deforms to touch such bobbins and to apply the same to the fork-like elements.
14. The bobbin changer claimed in claim 13, wherein the rigid support comprises a tube which extends over the whole length of the spindle bank and which is formed, on the side near the fork-like elements, with a longitudinal aperture through which the duct distorts when a pressure above the ambient pressure exists in the duct, the tube being disposed preferably near the top end of the bobbins.
15. The bobbin changer claimed in claim 13, wherein the fork-like elements are borne by a pivoted member which extends over the length of the spindle bank, and actuating means for moving the pivoted member from an inoperative position -- in which the fork-like members extend vertically and so cannot immobilize the empty bobbins -- to an operative position -- in which the fork-like elements are horizontal and so can immobilize without locking the empty bobbins through the agency of the fork-like element and the deformable duct.
16. The bobbin changer claimed in claim 2, wherein the endless belt comprises a continuous belt; the support has a central part and two side parts with which the belt is engaged through the agency of angle-members secured to the central part; and each gripping device is rigidly secured to a bracket clamped to the endless belt, each bracket comprising a horizontal extension which bears by its inside surface on the side part of the belt and which is supported at the top by way of its top surface through the agency of the particular angle-member concerned.
17. A spindle type spinning machine including a bobbin changer according to claim 1.
18. A method of operating a bobbin changer of a spindle type spinning machine characterized by the following steps:
19. A method of operating a bobbin changer of a spindle-type spinning machine having a bank of spindles which bobbin changer has an endless belt with inner and outer horizontal runs lying in a common plane, the inner run being closer to the spindle than the outer run, comprising the steps of:
20. A bobbin changer for spindle type spinning machines comprising:
21. A spinning machine having a bobbin changer according to claim 20.
22. A bobbin changer for spindle type spinning machines comprising:
23. A spinning machine having a bobbin changer according to claim 22.
Description:
This invention relates to spinning machines comprising top-mounted vertical-axis rotating spindles arranged at intervals in a single row to form a spindle bank, the finished textile product being wound on to bobbins previously threaded on the spindles; such machines can be spinning machines, twisting machines, stranding machines, etc. A bobbin usually takes the form of a tube threadable on to a spindle and forming an axial core on which the textile product is wound until the bobbin is full.
The invention relates to the bobbin changers used in such machines to remove full bobbins and replace the same by empty bobbins, apparatus of this kind hereinafter being referred to as a bobbin changer.
The invention also relates to a method of using the bobbing changer.
Bobbin changers are known wherein a driving motor is adapted to drive an endless belt or the like between two pulleys disposed one at each end of the spindle bank, the endless belt having gripping devices which serve to engage the bobbins and which are arranged at the same spacings from one another as the between-spindles spacings, the two pulleys being disposed on a support member actuated by a mechanism adapted to move such member vertically by an amount at least equal to effective spindle height. Bobbin changers of this kind have disadvantages, mainly because the two runs of the endless belt are disposed in the same vertical plane, with the result that the top run cannot be used. Only the bottom run can be used, and it is used first to disengage or release the full bobbins and only subsequently to position the empty bobbins, with the result that the machine must be stopped before the bobbin changer is used.
The invention relates to an endless-belt type bobbin changer free from these disadvantages.
The invention also relates to an endless-belt type bobbin changer in which both runs of the belt can be used.
The invention also relates to an endless-belt type bobbin changer in which, while the machine continues to operate, one run of the belt can be loaded with the number of empty bobbins required for the spindle bank.
The bobbin changer according to the invention comprises:
An endless belt drivable by a driving motor between two pulleys disposed one at either end of the machine spindle bank, the endless belt being disposed on a support parallel to the spindle bank;
Gripping devices, which are borne by the endless belt and which are arranged at the same intervals as the between-spindles intervals, each such gripping device being adapted to engage and then disengage the end of a (full or empty) bobbin when the gripping device moves in a horizontal plane relatively to the particular bobbin concerned, and
a first mechanism adapted to move the support vertically by an amount at least equal to effective spindle height, and is characterized in that:
the number of gripping devices is at least twice the number of spindles to be served;
the support for the endless belt is adapted to maintain each of the two runs of the endless belt in the same horizontal plane;
a loading station for the empty bobbins is disposed at one end of the machine so that when the endless belt moves in a direction such that each gripping device comes near the loading station and then passes to the outer run of the endless belt, the gripping device engages an empty bobbin, so that when a number of empty bobbins equal to the number of spindles of the spindle bank have been engaged, the outer run of the endless belt has been loaded with empty bobbins, and
an unloading station for the full bobbins is disposed at the other end of the machine, so that when the endless belt moves in the opposite direction, each gripping device passing near the unloading station and then going on to the outer run disengages a full bobbin, so that when the empty bobbins of the outer run have passed to the inner run, all the full bobbins have been disengaged, as they pass near the unloading station, so that the outer run of the endless belt is empty once the empty bobbins have passed on to the inner run.
Preferably, it also comprises a second mechanism for moving the endless-belt support horizontally, and perpendicularly to the direction in which the spindle bank extends, between a near position -- in which the inner run is in the vertical plane of the spindle bank -- and a remote position -- in which the inner run is in a free vertical plane -- the loading station and unloading station being on the path of the endless belt when the support thereof is in such remote position.
In the method for using the bobbin changer according to the invention:
the driving motor of the endless belt is operated to move the belt continuously in the engagement direction -- the direction in which the gripping devices engage an empty bobbin as they pass near the loading station -- this operation lasting until the outer run has been charged with empty bobbins;
subsequently the gripping devices are moved into the plane of the full bobbins on the spindles of the spindle bank and the full bobbins are engaged by the gripping devices on the inner run of the belt, such engagement being produced by a small movement of the belt in the engagement direction;
the first mechanism is then operated to raise the endless-belt support by a height at least equal to the effective height of the spindles so as to remove the full bobbins therefrom;
the belt-driving motor is operated to move the belt continuously in the disengagement direction -- the opposite direction to the engagement direction -- so that the gripping devices release a full bobbin as they pass near the unloading station, this operation lasting until the empty bobbins initially on the outer run have passed over to the inner run, all the full bobbins having by then been released and the outer belt run being empty at the end of working;
all the empty bobbins are placed above the spindles so that each empty bobbin is in vertical alignment with a spindle;
the first mechanism is operated to lower the endless-belt support so as to position each empty bobbin on a spindle, and
the empty bobbins are simultaneously released from their gripping devices, such release being initiated by a small movement of the endless belt in the release or disengagement direction.
The invention can in any case be readily understood from the remainder of the description, given hereinafter, and from the accompanying drawings, such remainder and drawings disclosing a preferred embodiment of the invention but not of course being limitative.
In the drawings:
FIG. 1 is a diagrammatic elevation of a spinning machine according to the invention and in particular, of the bobbin changer therefor;
FIG. 2 is a section on the line II--II of FIG. 1;
FIGS. 3 to 8 are diagrammatic views of the apparatus shown in FIG. 1 in different positions;
FIG. 9 is an enlarged section on the line IX--IX of FIG. 5;
FIG. 10 is an inverted plan view of an important element of the bobbin changer of the spinning machine shown in FIG. 1;
FIG. 11 is a diagrammatic perspective view of one of the two ends of the apparatus according to the invention, and
FIG. 12 is an enlarged section along the line XII--XII of FIG. 8 showing a variant of the invention.
As can be seen in FIGS. 1 and 3 to 8, the spinning machine comprises, top-mounted vertical-axis rotating spindles 1 arranged at regular intervals in a single row to form a spindle bank 2. Empty bobbins 3 are first threaded on to the spindles 1; bobbins 3 take the form of an axial core (cardboard tube) on to which the textile product is wound until the bobbin becomes a full bobbin 4 as shown in FIG. 9. A spinning machine of this kind comprises a bobbin changer which has the general reference 5 and which serves to remove full bobbins 4 and replace them by empty bobbins 3.
The bobbin changer 5 comprises:
an endless belt 6 drivable by a driving motor 7 between two pulleys 8 disposed one at each end of the spindle bank 2, the belt 6 being disposed on a support member 9 which extends parallel to and over the whole length of the spindle bank 2;
gripping devices 10 borne by the belt 6 and evenly distributed at the same spacings as the between-spindles spacings, each gripping device 10 being adapted to engage the top end of an empty bobbin 3, and subsequently release the top end of a full bobbin 4, when moving relatively to the particular bobbin concerned in a horizontal plane, and
a first mechanism 11 which is shown in FIG. 1 and which can move the endless-belt support 9 vertically by an amount at least equal to the operative height of the spindles 1 (bobbin engagement height).
According to the invention, the bobbin changer 5 is characterized in that:
the number of gripping devices 10 is at least twice the number of spindles to be served;
the support 9 for the endless belt 6 is adapted to maintain each of the two runs of the endless belt 6 in the same horizontal plane;
a loading station 17 for the empty bobbins 3 is disposed at one end of the machine so that when the endless belt 6 moves in a direction such that each gripping device 10 comes near the loading station 17 and then passes to the outer run of the endless belt 6, the gripping device engages an empty bobbin 3, so that when a number of empty bobbins 3 equal to the number of spindles 1 of the spindle bank 2 have been engaged, the outer run of the endless belt 6 has been loaded with empty bobbins 3, and
an unloading station 18 for the full bobbins 4 is disposed at the other end of the machine, so that when the endless belt moves in the opposite direction, each gripping device 10 passing near the unloading station 18 and then going on to the outer run disengages a full bobbin 4, so that when the empty bobbins 3 of the outer run have passed to the inner run, all the full bobbins 4 have been disengaged as they pass near the unloading station 18, so that the outer run of the endless belt 6 is empty once the empty bobbins 3 have passed on to the inner run.
Preferably, the bobbin changer 5 also comprises a second mechanism 12 for moving the endless-belt support 9 horizontally, and perpendicularly to the direction in which the spindle bank 2 extends, between a near position -- in which the inner run is in the vertical plane of the spindle bank 2 -- (FIGS. 4, 5 and 8) -- and a remote position -- in which the inner run is in a free vertical plane -- i.e., clear of any obstacle formed by machine parts (FIGS. 3, 6 and 7) -- the loading station 17 and unloading station 18 being on the path of the endless belt 6 when the support 9 thereof is in such remote position.
Preferably, and as shown in FIGS. 3 to 11, each gripping device 10 comprises a hook whose bottom part has two horizontal arms 13, 14 and each bobbin has at its top end a cylindrical stud or pin or the like 15 which is coaxial of the bobbin and whose bottom diameter is less than the separation between the two arms 13, 14 of the gripping device 10, the stud terminating in a circular head 16 whose diameter is greater than the separation between the two arms 13, 14 of the gripping device 10.
Consequently, when the belt 6 moves in the engagement direction, which must be such that the U-hooks forming the gripping devices 10 have their open part facing the direction of the movement, empty bobbins 3 at the loading station 17 (FIG. 11) are engaged or full bobbins 4 still operatively connected to their respective spindles 1 (FIGS. 4 and 5) are engaged. The movement is either continuous (consecutive engagement of empty bobbins 3 at loading station 17) or of small amplitude (simultaneous engagement of the full bobbins 4 still operatively connected to their respective spindles 1).
Disengagement of the full bobbins 4 at the unloading station 18 (FIG. 5) and of empty bobbins 3 which have just been operatively connected to their respective spindles 1 occurs when the endless belt 6 moves in the disengagement or release direction, and so the same must be such that the U-hook gripping devices 10 have their closed part facing in the direction of such movement. The same is either continuous (consecutive release of full bobbins at unloading station 18) or of small amplitude (simultaneous release of empty bobbins 3 which have just been operatively connected to their respective spindles 1).
Advantageously, the loading station 17 comprises a movable element adapted to be brought near the belt 6 for the operations of empty spindle engagement and to be moved away from the belt 6 upon the completion of the latter operations. As FIG. 11 shows, the loading station 17 comprises a movable waiting spout 48 in which a number of empty bobbins 3, e.g. three empty bobbins, are disposed vertically with their cylindrical studs 15 uppermost. For engagement of the empty spindles 3, spout 48 is brought into such a position -- the position shown in FIG. 11 -- that the cylindrical stud 15 of whichever bobbin 3 is nearest the spout aperture is on the path of the gripping devices 10. A feeder (not shown) introduces a fresh empty bobbin 3 into spout 48 whenever an empty bobbin 3 has been engaged.
Advantageously, the unloading station 18 comprises a moving element adapted to be moved near the belt 6 for full bobbin release operations and to be moved away from the belt 6 upon the completion of such operations. As FIG. 6 shows, station 18 comprises a stop finger 18a which, when near the belt 6, stops the progress of each full bobbin 4 seriatim and initiates release thereof by disengagement of the stud 15 from the arms 13, 14 of each device 10.
Advantageously, the first mechanism 11 can be embodied as shown in FIG. 1. The first mechanism 11 is a parallelogram mechanism comprising a number of long rods 19 each articulated to the endless-belt support 9 and to a member 20 movable parallel thereto, each long rod 19 being articulated at its center to a short rod 21 whose length is half the length of the long rod 19, the short rod 21 being articulated to a bottom frame 22. At least one moving part 20, preferably each such part, has a tapped portion and can be moved parallel to support 9 by a worm 23 which extends along the whole length of bottom frame 22 and which is rotatable to either hand by a motor-reducer set 24. The bottom frame 22 is borne by horizontal rails 25 on which frame 22 can make a horizontal movement perpendicular to the direction in which spindle bank 2 extends.
In this event, the second mechanism 12 can be embodied as shown in FIG. 2. The second mechanism 12 is an actuator mechanism comprising a number of screw actuators 26 whose respective rods 27 are connected to the bottom frame 22, the screw of each such actuator 26 co-operating with a tapped nut 28 in engagement with a driving gear 29 secured to a drive shaft 30 extending over the whole length of the bottom frame 22 and drivable to either hand of rotation by a motor-reducer 31. A feature provided by the second mechanism 12 is that the system formed by the belt 6 and the belt support 9 can be moved into a wholly or partly retracted inoperative position. For instance, as shown in FIG. 2, this system can be brought to a bottom position by operation of the first mechanism 11, and then, through the agency of the second mechanism 12, be withdrawn wholly or partly below the machine. In FIG. 2, the position A of the endless belt and support system is the extended or outside position in which such system can be raised to the spindle bank 2, the position B being the fully retracted inoperative position below the machine.
Advantageously, to facilitate the positioning of each empty bobbin 3 above the spindle 1 on which such bobbin is to be placed, centering means can be provided which can be operated selectively and which can immobilize, without blocking, each empty bobbin 3 above the corresponding spindle 1. As can be seen in FIGS. 7 to 9 and 11, the centering means can take the form of: fork-like elements 32 having two horizontal arms 33, 34 and a permanent magnet 35 secured therebetween, each such element 32 being disposed above the corresponding spindle 1 (FIGS. 7 and 8); and rings 36 which are made of a ferromagnetic substance and which are rigidly secured to the bottom part of each bobbin (FIGS. 9 and 11).
Alternatively, as shown in FIG. 12, the centering means can take the form of: fork-like elements 50 having two horizontal arms 51, each such element 50 being disposed above the corresponding spindle; and a closed duct 52 which is made of a deformable substance and which extends over the whole length of the spindle bank and which is retained by a rigid support 53, the latter being, with advantage, rigidly secured to the endless-belt support 9, the duct 52 being disposed on the side where the fork-like elements 50 are open and being so disposed relatively to the endless-belt inner run that, when the pressure in the duct 52 is the ambient pressure, such duct does not touch the empty or full bobbins hung on the gripping devices 10 of the endless-belt bottom run, but when a pressure above ambient pressure exists in the duct 52, the same deforms to touch such bobbins and to apply the same to the fork-like elements 50.
Advantageously, the rigid support 53 comprises a tube 54 which extends over the whole length of the spindle bank and which is formed, on the side near the fork-like elements 50, with a longitudinal aperture 55 through which the duct 52 distorts when a pressure above the ambient pressure exists in the duct 52. Preferably, the system formed by the duct 52 and tube 54 is near the top end of the bobbins. In FIG. 12 the duct 52 is shown in its distorted or deformed position in solid lines and in its inoperative position in chain-dotted lines.
Preferably, the fork-like elements 32 or 50 are borne by a pivoted member 37 which extends over the length of the spindle bank 2 and which can be moved by actuating means from an inoperative position -- in which the fork-like members 32 or 50 are folded upwards or downwards and so cannot immobilize the empty bobbins 3 -- to an operative position -- in which the fork-like elements 32 or 50 are horizontal and so can immobilize without locking the empty bobbins 3, either through the agency of the system comprising the magnet 35 and the ring 36 or through the agency of the system comprising the fork-like element and the deformable duct 52.
Turning now in more detail to the system comprising the endless belt 6 and its support 9, as can be seen in FIG. 9, the belt 6 is, with advantage, in the form of a reinforced plastics belt having clamped thereto brackets 38 each having rigidly secured thereto a gripping device 10. The support 9 comprises a central portion 39 and two side portions 40, 41 preferably made of a plastics such as nylon, on which the belt 6 is retained through the agency of angle members 42 secured to the central portion 39 and acting via the brackets 38 on the belt 6. Each bracket 38 comprises a horizontal extension 43 bearing by its bottom surface on the side part 40 or 41 and being retained at the top by its top surface through the agency of the particular angle-member 42 concerned. Consequently, when the gripping devices 10 are urged up or down during bobbin-changer operation, the support member 9 takes up the forces acting on the gripping devices 10 and ensures satisfactory retention of the belt 6.
Advantageously, and as shown in FIGS. 9 and 10, each gripping device 10 can comprise a retaining member 44 adapted to allow entry of the cylindrical stud 15 of each bobbin 3 between the two horizontal arms or branches 13 and 14 of the hook-like device 10 and to oppose, but not prevent, removal of the stud 15 from between the tow arms 13 and 14. The retaining member 44 can have near the device 10 a ramp 45 which is slightly inclined relatively to the belt 6 and which is near the open part of the hook 10, and the ramp 46 which is perpendicular to the belt 6 and which is near the closed part of the hook, the two ramps 45, 46 being connected to the hook structure by a resilient strip 47 visible in FIGS. 9 and 10.
One method of using the bobbin changer 5 according to the invention has already been described.
In the case of that embodiment of the bobbin changer 5 which has been more particularly described, the method of using the bobbin changer 5 is as follows:
the second mechanism 12 is operated to move the endless-belt support 9 from its retracted inoperative position B to its outside position A (FIG. 2);
the first mechanism 11 is operated to raise the support 9 as far as the top part of the waiting spout 48 (FIG. 11);
the said spout 48 is brought into the position in which the cylindrical stud 15 of the empty bobbin 3 near the opening of the spout 48 is on the path of the gripping devices 10 (FIG. 11);
the driving motor 7 of the endless belt 6 is operated to move the same continuously in the engagement direction, indicated by an arrow F a , in which direction the U-hooks forming the gripping devices 10 have their open part facing forwards to engage an empty bobbin 3 as they pass near the loading station 17, this operation lasting until the outer run of the endless belt 6 has been loaded with empty bobbins 3, this engagement being performed at the rate of 40 empty bobbins/minute (FIG. 11);
the first mechanism 11 is operated to lower the endless-belt support 9 so that the bottom part of the gripping devices 10 is near the cylindrical studs 15 of the full bobbins 4 in engagement with the spindles 1 of the spindle bank 2 (FIG. 3);
the second mechanism 12 is operated to bring the inner run of the endless belt 6 into the plane of the spindle bank 2 (FIG. 4);
the full bobbins 4 on the spindle-bank spindles 1 are all engaged simultaneously by the gripping devices 10 disposed on the inner run of the endless belt 6, such engagement being initiated by a small movement of the endless belt 6 in the engagement direction F a (FIG. 5);
the first mechanism 11 is operated to raise the endless-belt support 9 through a height slightly greater than the effective height of the spindles 1 to release the full bobbins 4 therefrom (FIG. 5);
the second mechanism 12 is operated to move the support 9 away from the spindle bank 2 (FIG. 6);
the belt-driving motor 7 is operated to move the belt continuously in the release direction, indicated by an arrow F b , in which direction the U-hooks forming the gripping devices 10 have their closed part facing forwards to release a full bobbin 4 as they pass by the unloading station 18, this operation lasting until the empty bobbins 3 which were initially on the outer run have passed to the inner run, all the full bobbins 4 having by then been released and the outer belt run being empty at the end of working, this disengagement being performed at the rate of 120-150 bobbins/minute (FIG. 6);
the pivoted member 37 is brought into its operative position in which the fork-like members 32, 50 are horizontal (FIG. 7);
the second mechanism 12 is operated to bring the belt inner run into the plane of the spindle bank 2, the empty bobbins 3 secured to the gripping devices 10 of the inner run being immobilized by the fork-like members 32, 50 immediately above the corresponding spindles 1 either by the magnet 35 (FIG. 8) or by the duct 52 (FIG. 12);
the first mechanism 11 is operated to lower the endless-belt support 9 through a height sufficient to position each empty bobbin 3 on spindle 1;
the first mechanism 11 is operated to raise the support 9 slightly so as to slightly raise the bottom part of the gripping devices 10 relatively to the top surface of the empty bobbins 3;
the empty bobbins 3 are released simultaneously by the gripping devices 10, the release being initiated by a small movement of the belt 6 in the release direction F b (FIG. 6);
the second mechanism 12 is operated to move the support 9 away from the spindle bank 2;
the first mechanism 11 is operated to lower the support 9 in its extended position A (FIG. 2); and
the second mechanism 12 is operated to move the support 9 from its extended position A into its retracted normal position B (FIG. 2).
The various sequences in the method just described can, with advantage, be automated by a programming system such that the completion of any one sequence triggers the next sequence.
The bobbin changer according to the invention has a number of advantages, some of which can be summarized as follows:
the possibility of using both runs of the endless belt;
the possibility of loading the required number of extra bobbins on to the outer run while the machine continues to operate;
simple gripping devices, which can engage full bobbins and release empty bobbins without risk of "failures;"
accurate positioning of each empty bobbin above the corresponding spindle, thanks to the centering means, this position occuring simultaneously and substantially instantaneously for all the empty bobbins.
In connection with the two latter features, gripping means retaining the (empty or full) bobbin in pendulum fashion (so that the bobbins can be engaged and released without failures) can be very useful when associated with centering means to ensure accurate and simultaneous positioning of each empty bobbin above the corresponding spindle.
Clearly, and as the foregoing shows, the invention is not limited to those of its uses or to those embodiments of its different parts which have been more precisely indicated, but covers all variants.