This invention relates to a rotary carding cylinder which is provided with a toothed wire clothing on its outer periphery, and which is mounted in a carding engine to cooperate with a taker-in, a doffer, and a series of flats cooperable with the toothed wire on the outer periphery on the cylinder in order to carry out a carding operation, in which the carding cylinder is provided with an internal cooling system to remove heat generated during operation of the carding engine.

The preferred application of the invention is to a rotary cylinder of a revolving-flat type carding engine in which a fibrous feed stock undergoes a carding operation along an arc of interaction between the cylinder periphery and a working path of movement of the flats alongside the outer periphery of the cylinder.

In order to carry out an efficient carding operation, it is important to maintain a small flats/cylinder clearance, typically of the order of about 0.008 inches and down to 0.005 inches for a cotton feed stock. The cylinder rotates at high peripheral speed relative to the linear speed of the flats, with a typical peripheral speed being of the order of, for example, 60,000 inches per minute, and a typical flats speed of about 6 inches per minute.

Given the nature of a carding operation, a substantial amount of mechanical work is carried out on the feed stock, and especially bearing in mind the narrow clearance between the flat and the cylinder periphery which defines the working volume in which the carding operation takes place. This mechanical work is derived mainly from the mechanical energy of the means driving the massive rotating cylinder, and is dissipated as heat. However, this heat tends to become trapped within the effective "hood" which the revolving flats ,- assembly forms in its positioning over the cylinder in the _f t space between the taker-in and the doffer.

With improved manufacturing standards, it is now

_* possible to set very close clearances between the flats and the cylinder, but this tends to increase the mechanical work

which is carried out and therefore the amount of waste heat which is generated. The cumulative effect of smaller clearances and expansion of the cylinder therefore aggravates this problem.

Therefore, while carding engines of the revolving flat type have operated satisfactorily for many years, there is now developing an appreciation that improved carding may be obtained by providing some means to extract waste heat from the carding cylinder.

This is now understood to be advantageous, particularly with closely set flats/cylinder clearance, in that localised heat generation will tend to cause differential thermal expansion within parts of the carding cylinder, which may result in alteration in the important flats/cylinder clearance from what is a preferred design setting. The cylinder ^' / doffer clearance may also vary to an undesirable extent.

With a view to solving this problem, the Applicants have developed an internally cooled carding cylinder which forms the subject of EP-0077166, and which has an external pump which delivers a pumped supply of coolant to the cylinder cooling system via a rotary connection. This has been found to cool the outer periphery of the cylinder and of the usual "spider" mountings at each end of the cylinder, and has an advantageous impact on the carding operation.

However, variation in flats / cylinder clearance and / or alteration of the peripheral speed of the cylinder can influence the amount of mechanical work which is done, while the cooling capacity of the cylinder remains largely constant, and therefore the cylinder periphery may tend to heat-up to unacceptable levels in certain conditions of operation, even though the cylinder is provided with an internal cooling system. Further, the use of a rotary connection between the pump circuit and the cylinder cooling systems requires careful design and assembly of suitable seals to avoid coolant leakage.

The present invention seeks to provide a novel coolant

pumping arrangement to operate an internal coolant system of a carding cylinder in a way which is self-compensating in that it can adjust its output according to cylinder speed, thereby to maintain the outer periphery of the cylinder at a reasonably steady temperature, or at least within a desired temperature band, sufficient to enable an efficient carding operation with close clearance settings being maintained and regardless of changes of cylinder speed, and / or operations with different types of feed stock.

According to the invention there is provided a carding cylinder having an internal cooling system arranged to route a flow of coolant to predetermined regions of the cylinder which require cooling and which comprises: a shaft on which the cylinder is mounted; a coolant flow path arranged within the cylinder and having an inlet end and a return end; a coolant inlet and a coolant outlet provided in the shaft and communicating respectively with the inlet and return ends of the coolant path; and, a centrifugal pump mounted on said shaft to rotate therewith and having a pump inlet communicating with said shaft outlet and a pump outlet communicating with said shaft inlet.

Therefore, in that the centrifugal pump is mounted on the same shaft as the cylinder, it will be driven at the same speed, or via gearing at a corresponding speed, and any increase in speed of the cylinder giving rise to increased mechanical work being done will also increase the speed of the pump and of its output, so that an increased rate of flow of coolant will be delivered by the pump in order to compensate at least partly for any increased tendency of the cylinder to heat up.

The coolant flow path will take any suitable form and arrangement in order to convey coolant to parts of the cylinder and associated components e.g. end mounting spider assemblies and flexible and fixed "bends" which control the movement of the flats.

Preferably, the pump is formed as a unit with a spider assembly at one end of the cylinder, and which are rotatable together, and therefore the routing of supply and return coolant paths between the pump and the internal coolant system of the cylinder via the spider does not need any rotary sealed joint since the spider assembly and pump rotate together at the same speed. This therefore provides an arrangement which can be designed to be substantially leak proof without need for any special design and assembly of suitable sealed rotary joints, which is a further significant improvement over the cooling system disclosed in EP-0077176.

In a preferred application of the invention, the carding cylinder is of a type used in a revolving-flat type carding engine. The routing of the coolant through the cylinder may generally be as disclosed in EP-77176. However, in a preferred arrangement, the coolant is first directed axially through the cylinder from a first end to an opposite end, radially outwardly towards the outer periphery (preferably internally within a usual spider assembly at this end), axially within the cylinder periphery back towards the first end, radially inwardly towards the shaft (again preferably internally within the usual spider assembly at this end), and then to the shaft outlet.

The drive shaft may extend continuously through the cylinder, Or may be formed by a pair of stub shafts mounting each end of the cylinder, and one, or both, or neither of which may be driven directly. If neither stub shaft is driven, then drive will be transmitted to the cylinder by other means, eg via a pulley or gear train coupled with the cylinder.

The centrifugal pump preferably comprises an outer housing mounted on the shaft to rotate therewith, a set of rotor vanes (blades) also arranged to rotate with the shaft, and a stator freely rotatable on the shaft and arranged to receive and to direct a pumped flow of coolant from the rotor vanes to the pump outlet.

Advantageously, fan blades are provided externally on

the pump housing to generate a flow of cooling air which is directed towards the cylinder, to pass around and / or through the cylinder when the pump housing is rotated.

The stator may have a set of fixed stator vanes to receive and direct the pumped flow of coolant, and a counter weight which generates a torque reaction sufficient to balance the action of the pumped flow of coolant on the stator vanes.

The counter weight may be approximately semi-circular and when the pump is at rest, it will take up a position under gravity action in which its exposed diametral face extends horizontally, but as the pump speed increases the counter weight is forced to pivot towards a maximum tilted position in which this face extends vertically, with the actual position adopted depending upon the speed of the pump and the rate of flow of coolant impinging on the stator vanes.

One embodiment of the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic illustration of the pumped routing of coolant through an internal cooling system of a rotary carding cylinder to which the invention may be applied;

Figure la is a schematic detail of a unitary assembly of pump unit and spider mounting at one end of the cylinder;

Figure 2 is a detail view, to an enlarged scale, of a centrifugal pump assembly mounted on the same shaft on which the cylinder is mounted, and which supplies a pumped supply of coolant along the internal cooling system of the cylinder; and,

Figure 3 is a side view, to a reduced scale, of the pump assembly shown in Figure 2.

Referring now to the drawings, a preferred embodiment of the invention will be described which comprises a rotary carding cylinder, preferably to be arranged in a revolving flat type carding engine. The carding cylinder is designated

generally by reference 10 in figure 1 , and will be provided with usual toothed wire clothing 11 on its outer periphery, which interacts with the confronting wire teeth of the flats of a revolving flats assembly in order to carry out a carding operation in well known manner. Very close clearances are presently set between the tips of the teeth of the flat and of the cylinder 10, and therefore substantial frictional and mechanical work is done on the fibrous feed stock during the carding operation. With a growing tendency for the clearances to be set ever closer, and with relatively higher speeds of revolution of the cylinder 10, this tends to generate substantial amounts of heat as a result of the increased amount of mechanical work being done, and this heat tends to remain trapped between the revolving flats assembly and the cylinder periphery.

The embodiment of the invention disclosed herein provides a novel coolant pumping arrangement to operate the internal coolant system of the cylinder 10 in such a way that it can adjust its output according to cylinder speed i.e. it is at least partly self-adjusting, thereby to maintain the outer periphery of the cylinder at a reasonably steady temperature, or at least wi ^' thin desired temperature bands, sufficient for efficient carding operations to take place regardless of changes of cylinder speed. Evidently, by maintaining the cylinder periphery within a preset temperature band during operation, fluctuations in clearance as a result of differential thermal expansion will be minimised.

The cylinder 10 is provided with an internal cooling system formed by a passage or passages extending internally within it in order to route a flow of coolant to predetermined regions of the cylinder which require cooling. A preferred routing is shown by the arrows in Figure 1. Alternatively, a coolant flow path as disclosed in more detail in EP-0077166 may be provided internally of the cylinder.

The cylinder 10 is mounted on a drive shaft which may

be formed by a continuous shaft 12 extending throughout the length of the cylinder 10, or by a pair of stub shafts 13 mounting each end of the cylinder 10. A centrifugal pump 14 is mounted on one end of shaft 12, or on one of the stub shafts 13, to rotate therewith, and has a pump inlet communicating with a coolant outlet formed in the shaft and a pump outlet communicating with a shaft coolant inlet leading to the interior of the shaft.

Therefore, as shown in Fig 1, a flow passage 15 extends from a shaft inlet 16 axially throughout the length of the cylinder from one end to an opposite end, and then is routed radially outwardly towards the cylinder periphery through a spider assembly (not shown), and then a return passage 17 extends axially in an opposite direction along the cylinder periphery to cool the latter and towards the first end of the cylinder, before being routed radially inwardly through another spider assembly towards the shaft and then returns to shaft outlet 18 where the coolant returns to the interior of the pump 14 to be pumped again around the system.

To further improve the cooling of the cylinder 10, and / or associated adjacent components of a carding engine e.g. known so-called flexible and fixed "bends", fan blades 32 may be mounted externally on the pump housing to rotate therewith and direct cooling air around and / or through the cylinder 10.

Figure 1 shows schematically the application of the invention to a rotary carding cylinder, and Figure la shows schematically the assembly of pump 14 to a usual end spider mounting 30 on which the hollow shell 31 of cylinder 10 is mounted.

The pump 14 and spider 30 are rotatable together as a unit with the cylinder shaft; and spider 30 is also rigidly secured to shell 31, and therefore pump 14, spider 30, shell 31 (and also the spider (not shown) at the other end of the shell 31) form a unitary assembly and which rotate together at the .same speed. Therefore, the routing of supply and return coolant paths between the pump.14 and the internal

coolant system of the cylinder 10 via the spiders does not need any rotary sealed joints since the components of the unitary assembly rotate together at the same speed.

This enables a substantially leakproof assembly to be made simply and without need for any special design and assembly of rotary sealed joints.

Referring now to Figures 2 and 3, the centrifugal pump 14 comprises an outer housing 19 which is mounted on the cylinder shaft to rotate therewith, and a set of rotor vanes 20 also are driven by the cylinder shaft to exert the pumping action. There is also a stator 21 which is freely rotatable on the cylinder shaft and is arranged to receive and to direct a pumped flow of coolant derived from the rotation of the vanes 20 to the pump outlet.

Figure 2 shows pump inlet 22 which receives the returning coolant flow from the cylinder via shaft outlet 18, and the arrows in Figure 2 show the routing of the coolant through the interior of the pump housing 19.

The stator 21 has a set of fixed stator vanes 23 which receive and direct the pumped flow of coolant from the vanes 20 radially inwardly towards pump outlet 24 which communicates with shaf inlet 16 to deliver a pumped supply of coolant to the internal cooling .system of the carding cylinder.

^' The stator 21 also includes a semi-circular counter weight 25 which generates a torque reaction sufficient to balance the action of the pumped flow of coolant onto the stator vanes 23. As shown in Figure 3, to a reduced scale, the counter weight 25 is caused to pivot through approximately 90 ^* from its rest position under the action of the rotation of the pump and the pumped flow of coolant onto the stator vanes 23. The actual position adopted by the counter weight 25 will depend upon the speed of the pump and the rate of flow of coolant impinging on the stator vanes 23.

The illustrated embodiment provides an entirely self- contained internal pumped coolant system, and the faster the speed of rotation of the cylinder 10, the greater will be the

rate of flow of coolant. The embodiment of the invention therefore provides an elegant mechanical solution to the problem of providing a cylinder coolant system having a cooling capacity which substantially matches the cooling requirements of the cylinder for a range of cylinder speeds and / or a range of different levels of mechanical working action on the vibrous feed stock.

It should be appreciated that the general concept of the driven centrifugal pump arrangement shown, by way of example only, in the application to the cooling of a carding cylinder of a revolving flats type of carding engine, can readily be applied to other carding cylinders which require an internal cooling system.