TUFTINGMASCHINE

Description

[0001] The present invention relates to a tufting machine.

[0002] In particular, it relates to the mechanism for reciprocating the needle bar of the tufting machine. The speed of reciprocation of the needle bar determines the rate at which tufts can be formed in the backing material as it is fed through the tufting machine. There is a need to increase this speed in order to improve the productivity of the machine. However, the mechanism driving the needle bar comprises a complex arrangement of rotating, cranked and linearly reciprocating components such that their speeds of reciprocation are limited by vibration / balancing issues.

[0003] US 4665845 discloses a single drive shaft which is connected to a number of the pushrods across the machine in order to reciprocate each of the pushrods simultaneously thereby reciprocating the needle bar.

[0004] This was improved upon in US 5287819 which uses a pair of drive shafts which are driven by a single motor and are connected together by a timing belt. This was done to provide a dynamically balanced machine which can be operated at a higher speed.

[0005] This was followed by US 5572939 which criticizes US 5287819 for its use of a second drive shaft with the associated support and reversing drives at each end. The solution offered by US 5572939 is to dispense with a second drive shaft of US 5287819 and revert to a single drive shaft as in US 4665845. This time alternate drive assemblies for alternate pushrods are configured to rotate in opposite directions. The counter rotation of the drive assemblies serves to cancel a significant proportion of the horizontal rotational forces.

[0006] US 2018 / 266027 is another reference with a single drive shaft.

[0007] US 2015 / 247272 discloses a tufting machine with two drive shafts. Pushrods are connected to both shafts.

[0008] The present invention aims to improve upon the prior art in order to provide a drive mechanism which can reciprocate the needle bar at higher speeds while maintaining vibrations at an acceptable level.

[0009] According to the present invention, there is provided a tufting machine according to claim 1.

[0010] The present invention therefore reverts to the twin drive shafts of US 5287819. However, the problems identified in US 5572939 concerning the reversing drives are instead solved by providing each drive shaft with its own drive motor.

[0011] Furthermore, the forces required to drive the mechanism are now distributed across two motors which provides for more stable operation and create less vibration. Current tufting machines may produce fabrics with a width of five meters. As the components to drive the bedplate mechanisms and the motors to drive the shaft itself are situated at one or both ends of the shaft, the current drive shaft can be relatively long (current tufting machines can have shafts of more than seven meters), leading to more problems with vibrations.

[0012] When two drive shafts are used, instead of one drive shaft, with each drive shaft having its own motor, the pushrods to be reciprocated are distributed over these two shafts and hence over the two motors. A first set of pushrods is connected to the first drive shaft to be driven by this first shaft, rotating in a first direction and a second set is connected to the second drive shaft to be driven by this second shaft, rotating in a second direction, opposite to the first direction.

[0013] The inertia of each shaft is much lower compared to the situation of the single shaft with all loads and motors on the same shaft. If the inertia is lower, the natural frequency increases and this makes it possible to increase the speed. As the first set of pushrods alternate with the second set of pushrods, a significant portion of the horizontal components of the rotational forces are cancelled.

[0014] According to the invention, the first motor is connected to a first end of the first drive shaft and the second motor is connected to a second end of a second drive shaft which is opposite to the first end of the first drive shaft.

[0015] The two drive shafts are driven from opposite sides of the tufting machine thereby providing a balanced load while the significant separation of the motors provided by this arrangement further distributes the output forces from the motors as it prevents the pushrods furthest from the motor from lagging behind the pushrods closer to the motor. In addition, the position error will also be much smaller.

[0016] In order to optimise this effect, the two motors are preferably arranged such that the pushrods are symmetrically distributed over the drive shafts.

[0017] Each respective drive shaft is connected to the respective drive motor at a power input point, and to the respective pushrods at power output points axially spaced along the respective shaft, wherein the axial spacing between the power input point and the power output points is the same for both drive shafts. The connection between the drive motors and drive shafts may not be a direct connection but may be via an additional linkage such as a belt, chain or gear. The connection between the drive shafts and pushrods may not be a direct connection but may be via additional linkages such as an eccentric coupling with a connection rod and / or a belt, chain or gear.

[0018] The first and second drive shafts may rotate mechanically completely independently of one another. In this case, the rotation of the motors should be carefully controlled in order to ensure that they rotate in synchronisation to simultaneously reciprocate the first and second sets of pushrods. Preferably, the first and second drive shafts are rotatably connected together. This ensures that the two drive shafts are synchronised. This also further assists with the balancing of the loads across the tufting machine. This should be contrasted with US 5287819 in which the connection of the two drive shafts is necessary to transmit the driving force from a single motor from one shaft to the other. By contrast, in the present invention, the drive shafts are separately driven and are only connected to provide a simple way of guaranteeing the rotation of the two shafts in synchronisation.

[0019] An example of a tufting machine in accordance with the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a perspective view showing the top part of the needle bar drive mechanism within the head of a machine according to a first aspect of the invention; Figure 1A is a perspective part of the drive showing the coupling of the shafts; Figure 2 is a front view of a part of the needle bar drive mechanism, driving two pushrods; Figure 3 is a perspective view showing the principle operation; Figure 4 is a schematic plan view illustrating the principle of operation; Figure 5A is an end view of a first end of Figure 3; Figure 5B is an end view of the opposite end of Figure 3; Figure 6 is a perspective view of the lower part of the drive mechanism included for background interest only; and Figure 7 shows a first motor configuration of Figure 6.

[0020] Most parts of the tufting machine are conventional and are shown, for example, in US 4665845, US 5287819 or US 5572939.

[0021] The first aspect of the present invention relates to an improvement in the drive mechanism for the needle bar. The second aspect of the present invention relates to an improvement relating to the drive mechanism for the hooks (or loopers) and optionally also for the knife as described below. In the description below only the term "hook" is used and it should be understood that this also covers the looper. All of the remaining features of the tufting machine are conventional and are well understood in the art.

[0022] Figure 1 shows the drive mechanism for the needle bar.

[0023] As shown in Figure 1, there are ten pushrods 1 which extend vertically down from the drive mechanism 2. The pushrods 1 are connected at their lower ends to a needle bar (not shown) in a conventional manner. The pushrods 1 are driven synchronously so that the needle bar is driven to reciprocate in a vertical plane thereby driving needles in and out of a backing material which is fed laterally through the tufting machine in order to produce a tufted carpet.

[0024] The present invention is concerned with a drive mechanism which reciprocates the pushrods 1 which is described in greater detail with reference to Figures 1 to 5B. A drive mechanism is provided by a first drive shaft 3 and a second drive shaft 4 which extend parallel to one another across the full width of the tufting machine. The first drive shaft 3 is driven by a first motor 5 via a pair of pulleys 6 (of which only one is visible in Figure 1, the other being behind the first motor 5) and a belt 7. The second drive shaft 4 is similarly driven by a second motor 8 via a similar pair of pulleys 9 and belt 10.

[0025] Each drive shaft 3, 4 is rotatably supported by bearings (not shown) and drive assemblies 12 along the length of both shafts.

[0026] The synchronization of the shafts 3,4 can be controlled by the tufting machine controller and / or the motor controllers. Additionally or alternatively, respective pairs of helical gears 13 can be provided at each opposite ends of the shafts 3, 4 which mesh with one another to ensure that the two shafts 3, 4 rotate together. This is shown in greater detail in Figure 1A.

[0027] The manner in which the drive shafts 3, 4 are connected to the pushrods 1 is schematically illustrated in Figure 4. The drive assemblies are divided into two sets, namely the first set 12A connected to the first drive shaft 3 and a second set 12B connected to the second drive shaft 4. For simplicity Figure 1 illustrates five instances of each type of drive assembly. Figure 3 schematically illustrates one of each, while Figure 4 schematically illustrates two groups containing a drive assembly 12A, connected to the first drive shaft 3 and a drive assembly 12B, connected to the second drive shaft 4. In Figure 4, a rectangle indicates the groups as shown on the right side and the left side, and in between there is a symbolic representation of more groups.

[0028] The first 12A and second 12B drive assemblies alternates across the width of the machine and are alternately connected to the first 3 and second 4 drive shafts by first belts 15 and second belts 16, respectively. Figures 2 and 3 show such a group of a drive assembly 12A and a drive assembly 12B, respective in front view and in perspective view.

[0029] The drive assemblies 12A, 12B are essentially the same in most respects and the common features will be described below.

[0030] The first drive arrangement comprising the first motor 5 and first drive shaft 3 is essentially rotationally symmetrical with the second drive arrangement comprising the second motor 8 and second drive shaft 4, in that if one of the drive arrangements is rotated about central a vertical axis, it would map directly onto the other drive arrangement, in terms of the axial position of the power inputs and outputs for each drive shaft 3,4.

[0031] In other words, if respective drive shaft 3,4 is connected to the respective drive motor 5,6 at a power input point, and to the respective pushrods 1 at power output points axially spaced along the respective shaft, then the axial spacing between the power input point and the power output points is the same for both drive shafts 3,4. In addition, the distance between each motor 5,8 and its respective shaft 3,4 is also preferably the same for each drive arrangement, such that the same length belt 7, 10 is used in each case..

[0032] The only difference between the first 12A and second 12B drive assemblies is that for the first drive assembly 12A belt 15 is driven by the first drive shaft 3, while for the second drive assembly 12B, the belt 16 is driven by the second drive shaft 4.

[0033] The belts 15, 16 connect to a top pulley which, for each drive assembly 12A, 12B is rotatable with a stub shaft 29 which is eccentrically coupled to a connection rod 35 which reciprocates the pushrod 1 vertically in a manner well known in the art.

[0034] The shafts 29 for the first 12A and second 12B drive assemblies will therefore rotate in opposite directions. The axis lines of the stub shafts 29 lie all on the same line (see Figures 1 and 2). The shafts 3, 4 rotate in synchronisation in view of the helical gears 13 (or some other timing mechanism provided by the motor controllers or the tufting machine controller) so that the shafts 29 will rotate at the same speed in the first 12A and second 12B drive assemblies. The eccentric couplings between the shaft 29 and connection rod 35 have the same equivalent geometry for the first 12A and second 12B drive assemblies and the two eccentric couplings are in phase with each other. This geometry is symmetrical about a median plane so that the travel path of the connection rod 35 is the same for the first 12A and second 12B drive assemblies. The components of the drive units rotate in opposite phase, to ensure that their vertical component of movement is exactly the same. In this way the first and the second sets of pushrods are simultaneously reciprocated.

[0035] Although the above arrangement provides a well-balanced mechanism, some counterweighting may still be required in order to dampen any vibrations which naturally occur. This may take the form an eccentric weight mounted on the eccentric drive shaft 29, and / or a conventional eccentric mass to rotate with the first 3 and / or second 4 drive shaft.

[0036] Figure 6 shows a drive mechanism 50 for a bedplate component. This will be mounted, in use, in the tufting machine below the bedplate. In a conventional tufting machine, this would be connected by a mechanical linkage to be driven from the main drive assembly as described above.

[0037] The mechanism 50 shown in Figure 6 is for driving a hook shaft 51. However, the same principals also apply to the drive for the knife shafts.

[0038] The hook shaft is rocked to and fro (as described below) in order to move the hooks to and fro with respect to their respective needles, which are reciprocated up and down in order to pick up the loops of yarn of the needles.

[0039] The drive mechanism for the hook shaft 51 will now be described.

[0040] This takes the form of a pair of motors 53 which are positioned with one adjacent to each end of the hook shaft 51. The motor has a continuously rotating output shaft 54 which is coupled to the hook shaft 51 via an eccentric coupling 55. This comprises a connecting rod 56 rotatably and eccentrically mounted at its top end to the output shaft 54.

[0041] The bottom end of the connecting rod 56 is rotatably mounted to a bracket 57 attached to the hook shaft 51.

[0042] Rotation of the output shaft 54 causes the top end of the connecting rod 56 to orbit about the axis of the output shaft 54. On its upstroke, the connecting rod 56 lifts the bracket 57 and on its downstroke, it lowers it, thereby causing a rocking motion of the bracket 57 and hence the hook shaft 51.

[0043] The eccentric coupling is configured to provide the above-described rocking mechanism. The motors 53 effectively provide the rotational force which is previously provided in the prior art via the mechanical coupling to the main drive shaft. The motor is fitted at the point at which the coupling the main drive shaft is fitted in the prior art such that it can use any known coupling to the hook shaft 51. The drive mechanism is therefore significantly simpler and smaller than a coupling to the main shaft.

[0044] In a cut pile machine, there could be a dedicated set of motors for the hook shaft and the knife shaft, or both could be coupled to the same set of motors. A single motor could be provided in one side of the tufting machine. However, the use of a pair of motors provides a more balanced and better distributed drive.

[0045] The motor 53 is mounted directly to the eccentric coupling as shown in Figure 7. As an alternative, a belt may be provided to allow a coupling to an offset motor. This provides the option moving the motor to a different location should this be more convenient for the layout of a particular machine.

Claims

1. A tufting machine comprising: a plurality of pushrods (1) spaced across the tufting machine and which are simultaneously reciprocatable; a needle bar attached to the pushrods so as to be reciprocated by the pushrods to move needles on the needle bar, in use, through a backing medium fed through the tufting machine; a first drive shaft (3) rotatable in a first direction by a first motor (5), the first drive shaft being connected to a first set of the pushrods to reciprocate the first set of pushrods; and a second drive shaft (4) rotatable in a second direction opposite to the first direction by a second motor (8), the second drive shaft being connected to a second set of the pushrods to reciprocate the second set of pushrods; wherein the first set of pushrods alternate with the second set of pushrods across the tufting machine with the first set of pushrods being coupled to the first drive shaft but not the second drive shaft, and the second set of pushrods being coupled to the second drive shaft but not the first drive shaft; wherein the first motor (5) is connected to a first end of the first drive shaft (3) and the second motor (8) is connected to a second end of the second drive shaft (4) which is opposite to the first end of the first drive shaft, such that each respective drive shaft is connected to the respective drive motor at a single power input point.

2. A tufting machine according to claim 1, wherein the first (3) and second (4) drive shafts are rotatably connected together.

3. A tufting machine according to claim 3, wherein each respective drive shaft (3, 4) connected to the respective drive motor (5, 8) at the power input point, is connected to the respective pushrods (1) at power output points axially spaced along the respective shaft, and wherein the axial spacing between the power input point and the power output points is the same for both drive shafts.

4. A tufting machine according to claim 1, further comprising an auxiliary motor (53) coupled to rock a hook and / or knife drive shaft (51).

5. A tufting machine according to claim 4, wherein the auxiliary motor (53) is a rotary motor with a continuous unidirectional output coupled to an eccentric crank arm (55) to convert the continuous unidirectional output to a reciprocating rotary motion rock a hook and / or knife drive shaft (51).