US3484581A - Godet roll - Google Patents

Description

Dec. 16:, 1969 55 3,484,581

GODET ROLL Filed June 19. 1967 llmml HEATER CONTROL HEATER POWER SOURCE F/ 2 I INVENTOR.

GORDON L. BLISS his ATTORNEYS Patented Dec. 16, 1969 3,484,581 GODlET ROLL Gordon L. Bliss, Uxbridge, Mass, assignor to Whitin Machine Works, Inc, Whitinsville, Mass, at corporation of Massachusetts Filed June 19, 1967, Ser. No. 646,937 Int. Cl. B211) 27/06 US. Cl. 219--469 16 Claims ABSTRACT OF THE DISCLOSURE A godet roll comprising an inner heater section carrying a helically wound electrical heating coil, which is, preferably, cast in place during the manufacture of the heater section, and a removable outer sleeve received on the heater section. The temperature coefiicient of expansion of the heater section is greater than the outer sleeve, and the parts are dimensioned so that the sleeve can be slid relatively easily onto the heater section at ambient temperature but is held in place by an interference fit at operating temperature. A temperature sensor in the form of a resistance wire is wound helically around the heating section and is preferably located at the interface between the heating section and the outer sleeve at the zone of the roll where the material being treated leaves it.

BACKGROUND OF THE INVENTION This invention relates to a novel and improved godet roll.

In the manufacture of synthetic yarns, the synthetic fiber-forming material is extruded as a multiplicity of filaments, and the filaments are brought together and drawn. The drawing step is extremely important in the process because it determines, to a considerable extent, the mechanical properties of the yarn.

One type of drawing apparatus usedin the manufacture of synthetic yarns comprises a series of rolls called godet rolls. The yarn as it comes from the extruding device first makes a multiplicity of turns around a first stage of preheating godet rolls, which are rotating at a relatively slower speed, and then a multiplicity of turns around a stage of draw godet rolls, which operate at a relatively higher speed. In the process of transferring from the slower rolls to the faster ones, the yarn is pulled or drawn. In addition, it is given a heat treatment on the second stage rolls or a subsequent, third stage.

The necessity of maintaining the rolls at critical temperatures and of operating them at relatively high speeds creates a number of problems. Although a number of godet rolls of various constructions have been proposed each has one or more shortcomings. For example, one type of godet roll is composed of a rotating, bell-shaped roll which is heated from an annular, fixed heating unit received within the roll. The heat transfer in this type of roll is extremely poor, and the ability to control the temperature of the roll, particularly where the ambient conditions vary, is minimal. In another form, a solid roll is provided with circumferentially spaced-apart, longitudinally extending cartridge heating elements. Al though the heat transfer is significantly improved by providing the heat elements on the roll body, this form has a disadvantage of a lack of uniformity of temperature circumferentially around the surface of the roll. Moreover, refurbishing of the roll surface, being an integral part of the roll, is difficult and time-consuming.

SUMMARY OF THE INVENTION The foregoing and other disadvantages of godet rolls of the types previously suggested in the art are overcome, in accordance with the invention, by a novel and improved godet roll embodying a number of features that provide better heat transfer efficiency, the ability to achieve and maintain precise temperature control from a point remote from the roll, roll temperature uniformity, ease of roll surface refurbishing with a minimum of down time, and other improved characteristics. More particu larly, the godet roll of the invention comprises a heater section in the form of a generally cylindrical member, preferably of a material having high thermal conductivity, a heating element that rotates with the roll, and preferably encased within the heater section and forming a part of it, and an outer removable shell received on the heater section. The temperature coefficient of expansion of the heater section is greater than that of the outer sleeve, and the parts are dimensioned so that the sleeve can be slid relatively freely onto the heater section at ambient temperatures, but an interference fit is obtained at operating temperatures to securely hold the outer sleeve on the heater section.

In a preferred embodiment, the godet roll is heated by a rod-type electrical heating element that is helically wound, with respect to. the roll, and is preferably cast in place during the manufacture of the heater section. The temperature of the roll is controlled by a resistance wire sensor wound helically on the heater section, preferably at its periphery and thus the interface between the outer sleeve and the heater section. The roll includes a hub for cantilevering it from the shaft of a drive motor, and both the heating coil and the resistance wire leads are led through the motor shaft and are brought out through a slip ring to the temperature controller and the power source for the heater. The controller may be located at a point remote from the roll, such as in a main control console for the draw machine.

The heater section of the roll may be composed of an inner tubular member and a body portion which is cast using the inner shell as one mold part. Keepers for the electric heating element are attached to the inner shell prior to casting the heater section body and facilitate precisely locating the coil in the cast body to ensure heating uniformity.

The resistance wire heat sensor coil preferably occupies a circumferential band of fairly substantial width say, on the order of one quarter of the length of the roll, thereby providing a temperature measurement that is an average of a relatively large amount of surface area of the roll. The band occupied by the heat sensor coil may, to advantage, be located in the region of the point where the yarn leaves the roll, because the maximum temperature of the yarn as it leaves the roll is normally the best indicator of the overall heating. A further important advantage of a resistance wire heating control is that it is not sensitive to noise occurring at a slipring, inasmuch as it draws a fairly large current. Moreover, the resistance of the element is proportionate to the temperature, thus providing a relatively large control range. Moreover, the resistance wire sensor can be used at higher operating temperatures than other types of sensors, especially thermistors.

The invention offers numerous advantages. For one thing, the efficiency of heat transfer provided by mounting the heating coil for rotation with the roll surface is markedly better than in rolls in which the heating coil is fixed and is separate from the rotating roll. Heat transfer efiiciency is further enhanced by the interference fit at operating temperature between the sleeve and the heater section, the tightness of the sleeve on the heater section ensuring good contact and thus good heat transfer at the interface between the sleeve and heater section. The helical form of heating element considerably facilitates providing a uniform temperature about the circumference of the roll. Moreover, it provides for a predetermined temperature gradient longitudinally along the roll surface, a desired gradient being obtainable by varying the pitch of the helix as required to increase or decrease the degree of heating of any given circumferential section of the roll. The resistance wire temperature sensor, as mentioned above, provides excellent temperature detection, inasmuch as the effect of noise at the slip ring is negligible; moreover, the location of the sensor element over a fairly broad range of the roll provides an average value that is not susceptible to isolated variations. The construction of the roll, notably the relatively thin outer shell, facilitates locating the temperature sensor very near the roll surface, and preferably near the part of the length of the roll where the yarn leaves the roll, and it is therefore possible to employ the sensor not only as an element of the heater controller but also as a monitor of the operation of the roll, the resistance element forming a part of a measuring circuit providing a meter reading or a recorded value of temperature at all times during the operation of the roll.

The construction of the roll in two parts, namely the heater section and the outer sleeve, and using materials having different temperature coefficients of expansion makes it possible to replace the outer sleeve quickly and easily; this is of considerable advantage, inasmuch as costly down time for refurbishing the roll is kept at a minimum. Furthermore, the overall construction of the roll permits locating its center gravity relatively close to the motor and thus facilitates designing and balancing for higher operating speeds. The roll can be kept down to a relatively low weight, a further advantage for high speed operation. Preferably, the heater section body is formed of cast aluminum which offers the advantages not only of light weight but high thermal conductivity, and where the heater section is composed of two parts, the inner part may be steel which provides the strength needed for a high speed roll and also facilitates joining the roll to the shaft by means of a hub welded to the inner shell of the heater section. A preferred embodiment of the roll also includes cooling fins on the hub carrying the roll, thus inhibiting the heating of the shaft and the bearing in which the shaft is joumaled.

DESCRIPTION OF THE DRAWING For a better understanding of the invention, reference may be made to the following description of an exemplary embodiment, taken in conjunction with the figures of the accompanying drawing, in which:

FIG. 1 is a pictorial view showing, generally schematically, the overall layout of the godet roll, the drive motor and the heater control; and

FIG. 2 is a side view in cross-section, the section being taken generally at a diametrical plane of the roll and only a part of the drive motor being shown.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Referring first to FIG. 1, the godet roll, which is designated generally by the reference 10, is adapted to be mounted at one end of the shaft 12 of a motor 14. At the opposite end of the motor shaft 12 is a slipring unit 16 having four sliprings (not shown), two for connecting motor is shown in FIG. 1 schematically as being supported by a rigid horizontal surface, it is appropriate to mount the motor in any suitable manner on a frame and 4 in back of a panel (not shown), the roll 10 being mounted in front of the panel.

Referring next to FIG. 2, which shows the construction of the roll 10 and adjacent parts of the motor in more detail, the motor 14 includes an end bell 40 having a protective cover 41 attached to it and carrying a bearing 42 which in turn supports the motor shaft 12. Near the end of the shaft 12 is a tapered portion 12a which receives a hub 44 on the roll 10. The hub 44 is formed with an annular flange 44a carrying a heat sink in the form of a ring 46 having a plurality of outwardly extending cooling fins 48, the ring 46 being secured on the flange 44a by means of set screws 49. The hub also has an outwardly extending flange 44b having a series of cooling fins 440 formed in its rear surface. The fins 46 and 44c remove heat from the hub 44 and thus inhibit the heating of the shaft 12 and lower the operating temperature of the bearing 42. The hub 44 is secured to the shaft by means of a nut 50 threaded onto a threaded portion 12b at the end of the motor shaft 12.

The cylindrical body of the roll 10 is composed of a heater section 54 and an outer shell or sleeve 56 received on the heater section. The heater section 54 consists of two parts, an inner shell 58 which is preferably made of stainless steel and is joined by weldments 60 to the outwardly projecting flange 44b of the hub 44, and a body portion 62 surrounding the inner shell 58. The inner shell 58, as shown in the drawings, has a tapered wall thickness, the taper being in a direction moving away from the hub 44, but this feature is a matter of choice. The body 62 is preferably aluminum and is cast in place around the shell 58, the shell 58 serving as one mold part, and then machined to dimension. The material of the shell 58 and body 62 should have temperature coefficients of expansion of approximately the same magnitude in order that the thermal expansion does not cause the body 62 to become loosened on the shell 58.

The heat source for the roll 10 is a rod-type electric heating element 64 which is cast in place in the body portion 54. Prior to casting the body portion, the heating element is wrapped helically around the inner shell 58 and is located and held in position by slots 66a in circumferentially spaced-apart keepers 66 (of which only one is shown) which are welded or otherwise suitably attached to the outer surface of the shell 58. Advantageously the free ends 64a of the heating element 64 are brought in and connected to lead wires 68 and 69 located at diametrically opposite positions near the outer end of the shell, with respect to the motor, the heating element being wrapped in a double helix leading from the terminal points back toward a point near the hub 44 where a 180 bend 64b occurs. The lead wires 68 and 69 are connected to terminals 70 and 71 of an electrical coupling 72 that is threaded into the endportion 12b of the motor shaft 12. The shaft 12 has an axial bore 120 carrying a cable 74 connected to and leading from the coupling 72 back through the motor and into the slipring unit 16 (FIG. 1).

Because the heating element 64 wraps helically around the heater section, temperature uniformity in the circumferential direction is ensured. A desired temperature gradient in the lengthwise direction can be established, to a point, by varying the pitch of the helix as desired. On the other hand, the pitch cannot exceed a certain value, depending on the dimension from the sleeve outer surface to the heating element, without creating alternate hotter and cooler circumferential bands along the length of the roll.

The heater section 54 also carries a heat sensing element in the form of a resistance wire coil 78 installed in a helical groove 80 machined in the outer surface of the heater section body portion 62. The resistance wire coil extends over a circumferential band of relatively substantial width, say on the order of A of the total length of the roll 10, and is located adjacent the outer end of the roll 10. As will be described below, the yarn processed on the roll is led in adjacent the inner end of the roll (the end nearest the motor 14) and takes several turns helically outwardly along the roll where it leaves near the outer end. Thus the resistance wire coil is located in a region of the roll where the yarn leaves it. The ends of the resistance wire coil 78 are brought in through the shell 58 and connected to terminals 82 and 83 of the coupling 72 by leads 84 and 85 which are in turn coupled by means of the cable 74, the slipring unit 16, and leads 24 and 26 to the heater control 28 (FIG. 1).

The outer sleeve 56, which is preferably made of stainless steel and is chrome-plated, has a circumferential head or flange 56a at its inner end, with respect to the motor 14, and an end cover 88 joined, such as by welding, to its outer end, the end cover and therefore the sleeve being fastened by screws 90 to the body portion 62 of the heater section 54. Although the screws 90 serve to mount the outer sleeve 56 on the heater section 54 at ambient temperature, the primary means by which it is held on is by an interference fit established at operating temperature upon expansion of the parts of the roll 10.

More particularly, the material selected for the sleeve 56 has a temperature coefiicient of expansion that is somewhat less than the temperature coefiicient of expansion of the materials of the heater section 54, and the heater section and sleeve are dimensioned so that the shell 56 can be slid onto the outer surface of the heater section body 62 at ambient temperature. Upon heating, however, the heater section expands to a greater extent than the sleeve, thus bringing it into firm engagement with the sleeve and providing an interference fit between them.

The construction of the roll 10 in two parts, or more precisely in three parts, provides a number of significant advantages. First of all, the weight of the roll 10 is kept at a minimum without sacrificing strength, the heater section inner shell 58 and the outer sleeve 56 being of steel and providing strength and the body 62 being of aluminum and providing high thermal conductivity and low weight. Further, the construction facilitates the installation and replacement of the shell surface, should the need arise, thus making it unnecessary to replace an entire roll in the event of damage to its surface. Moreover, the outer shell 56 may have a relatively low wall thickness, thus making it possible to manufacture it without particularly high roundness tolerance requirements since it will conform to match the shape of the body 54 upon installation. The efficiency of heat transfer in the roll 10 is enhanced by the fact that the major part of the heat-conducting path from the heating element 64 to the surface of the roll 10 is through the aluminum or other high thermal conducting material, the outer shell being, as mentioned above, relatively thin. The center of gravity of the roll 10 is relatively near the inner end of the roll (with respect to the motor 14) thus, in conjunction with the light weight of the roll, making it better adapted for high speed operation.

In operation, two rolls of the type illustrated in the drawing are normally used together, being spaced apart and mounted with their axes slightly out of parallel so that the yarn, which makes several turns around them and spans the space between them, is fed from the inner ends of the rolls toward the outer ends. The roll surfaces are kept heated to a closely controlled temperature by controlled energization of the heating coil 64 from the heater power source 22, the power to the coil being proportional in response to signals through the conductors and 32 received from the heater control 28. The heater control 28, in turn, receives signals proportionate to the roll temperature, via the conductors 24, 26, the slip ring unit 16, the cable 74, and leads 84 and 85, from the resistance wire coil 78. It will be noted that the temperature sensor is, as mentioned above, located at the interface between the heater section 54 and the outer sleeve 56 of the roll and at the region of the roll where the yarn leaves it. Accordingly, the temperature detected by the sensor 78 is closely related to the temperature of the yarn as it leaves the roll. Moreover, it is an average value taken over a relatively large section of the roll. The loca tion and coverage of the sensor 78 provide rapid response and very accurate control. In practice, the temperature of the roll can be maintained within a fraction of degree of a predetermined desired temperature. Moreover, the indication of temperature yielded by the sensor 78 can also be used as a monitor value and the current (which is indicative of the resistance) applied to a meter or recorder to give a continuous reading or record of the roll temperature.

Replacement of the sleeve 56, should it become damaged, is accomplished quickly and easily when the roll is at ambient temperature by removing the screws holding the end cover 88 on the heater section and simply pulling the shell and cover longitudinally off the end of the heater section 54. Upon sliding a replacement sleeve 56 in place and installing the screws, the roll is ready for operation, and reheating of the roll 10 to operating temperature automatically creates an interference fit between the shell and heater section upon their thermal expansion.

The above-described embodiment of the invention is intended to be merely exemplary, and those skilled in the art will be able to make numerous variations and modifiations of it without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as defined in the appended claims.

I claim:

1. A godet roll comprising an inner heater section in the form of a member having a cylindrical outer surface and carrying heating means rotatable with the roll, and an outer removable cylindrical sleeve received on the heater section, the temperature coefficient of expansion of the heater section, being greater than that of the sleeve such that the sleeve is slidable onto the heater section at ambient temperature but is in interference fit with the heater section at the operating temperatures of the roll.

2. A godet roll according to claim 1 wherein the heating means comprises a rod-type electrical heating element wound helically with respect to the heater section.

3. A godet roll according to claim 2 wherein at least part of the heater section of the roll is cast of a highly heat conductive material, and wherein the electrical heating element is embedded in the cast part by being cast in place.

4. A godet roll according to claim 1 further comprising a temperature sensor in the form of a resistance wire wound on the heater section member helically with respect to the roll about a band of substantial width relattive to the longitudinal dimension of the roll.

5. A godet roll according to claim 4 wherein the band occupied by the resistance wire temperature sensor is disposed in the region of the roll where the product treated by the roll leaves the roll.

6. A godet roll according to claim 1 further comprising a shaft-mounting hub carrying the heater section and sleeve, the hub having cooling fins for removing heat from the hub and inhibiting the heating of a shaft carrying the roll.

7. A godet roll according to claim 3 wherein the heater section further includes an inner shell within the cast part, the shell and cast part having temperature coefiicients of expansion of the same order of magnitude to ensure against separation at the interface between them upon heating.

8. A godet roll comprising a drive motor having a shaft, a slip ring unit at one end of the motor and receiving the motor shaft, a cylindrical roll structure cantilevered from the other end of the motor shaft, the roll structure having an inner heater section in the form of a cylindrical member carrying heating means rotatable with the roll structure, and an outer cylindrical sleeve received on the heater structure, an electrical conductor cable extending through the motor shaft and coupled to the slip ring unit and including first conductor elements coupled to the heating means, a heater power source coupled through the slip ring unit and the said first elements of the conductor cable to the heating means, a resistance wire temperature sensor carried by the roll structure and rotatable with it and coupled to second elements of the cable, and heater control means connected through the slip ring unit and the said second elements of the cable to the temperature sensor for controlling the heater power source to maintain a predetermined temperature of the roll structure.

9. A godet roll according to claim 8 wherein the temperature coefficient of expansion of the heater section is greater than that of the sleeve such that the sleeve is slidable onto the heater section at ambient temperature but is in interference fit with the heater section at the operating temperatures of the roll.

10. A godet roll according to claim 8 wherein the heating means comprises a rod-type electrical heating element Wound helically with respect to the heater section.

11. A godet roll according to claim 10 wherein at least part of the heater section of the roll is cast of a highly heat conductive material, and wherein the electrical heating element is embedded in the cast part by being cast in place.

12. A godet roll according to claim 8 wherein the temperature sensor is Wound helically with respect to the roll about a band of substantial width relative to the longitudinal dimension of the roll.

13. A godet roll according to claim 12 wherein the band occupied by the resistance wire temperature sensor is disposed in the region of the roll where the product treated by the roll leaves the roll.

14. A godet roll according to claim 8 further comprising a hub carrying the roll structure and mounted on the motor shaft, the hub having cooling fins for removing heat from the hub and inhibiting the heating of the shaft.

15. A godet roll according to claim 11 wherein the heater section further includes an inner shell within the cast part, the shell and cast part having temperature cefiicients of expansion of the same order of magnitude to ensure against separation at the interface between the upon heating.

16. A godet roll comprising an inner heater section having an inner shell, a shaft-mounting hub joined to one end of the shell to receive a driving shaft for the roll, a body portion surrounding the sleeve cast from a highly heat conductive material and a rod-type electrical heating element wound helically within the body and around the inner shell and being embedded in the body by being cast in place, the shell and body of the heater section having temperature coefficients of expansion of the same order of magnitude; a thin-wall cylindrical sleeve surrounding the heater section and formed of a material having a temperature coefficient of expansion less than the temperature coefiicient of expansion of the inner shell and body of the heater section such that the sleeve is slidable onto the heater section at ambient temperature but is in interference with heater section body at the operating temperatures of the roll; and a resistance wire temperature sensor coil wound helically onto the heater section body and occupying a circumferential band of substantial width in the region of the roll Where the product treated by the roll leaves the roll.

References Cited UNITED STATES PATENTS 839,343 12/1906 Vogel 338--232 3,227,857 1/1966 Hill et a1 2l9469 3,296,418 1/ 1967 Johnson 2l9469 3,355,784 12/1967 Beyers et a1. 2l9469 3,286,081 11/1966 Scowcroft 2l9469 3,257,939 6/1966 McDermott 2l9469 FOREIGN PATENTS 264,755 10/ 1963 Australia.

GEORGE HARRIS, Primary Examiner FRED E. BELL, Assistant Examiner

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