Patent Publication Number: US-3879594-A

Title: Temperature measurement and control of rotating surfaces

Description:
United States Patent 11 1 1111 3,879,594 Shillito Apr. 22, 1975 1 TEMPERATURE MEASUREMENT AND 3.435.171 3/1969 Lohest 2l9/l0.6l A 3.529.116 9/1970 Miyagi 2l9/l0.6l CONTROL OF ROTATING SURF CES 3.612.830 10/1971 Dienes 219/471 [76] Inventor: Terence Graham Shillito, PO. Box  
  16 Pastor Manchester- M22 Primary Examiner-Bruce A. Reynolds v Lancashll&#39;e- England Attorney, Agent, or Firm-Browdy and Neimark [22] Filed: Sept. 26, 1973 917 [57] ABSTRACT [21] Appl Means for transferring heat to a moving filament in a filament processing machine wherein a rotatable roller [30] Foreign Application Priority Data or endless belt contacting the filament is heated from Sept. 29, 1972 United Kingdom 44944/72 Stationary heat Source For Sensing the temperawre of the contacting surface of the roller or belt a tem- [52] US. Cl. 219/1049; 73/351&#39;, 219/1061; perature sensor extends into a pocket formed in a side H 219/469 edge of the roller or belt, the pocket extending paral- [51] Int. Cl 1105b 5/06; HOSb 3/02 161 With and j cent o the Contacting surface. The [58] Field of Search 219/ 10.49, 10.61, 10.77, sensor is mounted on an intermediate pp hi 219/469, 470, 471; 73/351; 338/28, 159 in turn is mounted on the machine frame. There is a 7 high thermal resistance between the intermediate sup- 5 References Ci d port and the sensor and between the support and the UNITED STATES PATENTS frame. The support is in good thermal contact with the 3.369.106 2/1968 TFO&#34; 219/469 x 3,417,226 12/1968 Thomiszer 219/469 X 7 Claims, 4 Drawing Figures TEMPERATURE MEASUREMENT AND CONTROL OF ROTATING SURFACES This invention relates to heat transferring means.  
  In many technological processes it is required to transfer heat to a rapidly moving filament and to be able to control the heat take-up of the filament to within narrow limits. Examples are the drawing and texturising of synthetic natural-fibre substitutes or alternatives. It is often convenient to transfer the heat at a rotating roller which also imparts the transport energy by having the filament wound round a cylindrical surface concentric with the axis of rotation. The critical processing parameter is the temperature of the filament, which due to its intimate contact with the rotating cylindrical surface is at atemperature substantially equal to the temperature of that surface.  
  Supplying heat energy to the rotating roller by means normally used for stationary members leads to considerable maintenance problems due to the sliding surfaces involved. Methods of overcoming this problem are known, one being to induce electrical currents into the roller, thereby transferring energy through the stationary medium through which the roller rotates without mechanical friction.  
  In order to be able to control the amount of heat supplied to give the correct processing temperature it is necessary to be able to measure the temperature of the moving filament or some other body whose temperature has an unvarying relationship with the filament temperature. Due to the last qualification the alternatives to the filament temperature will be bodies that are rotating in intimate contact with the filament while it is receiving heat from the rotating roller, and this implies that the heat controlling equipment must either rotate with the roller or that the temperature sensing signal must bridge the gap between the rotating roller and some non-rotating location.  
  Methods are known which use the radiant energy from either the filament surface or some alternative surface that is well coupled thermally to the filament surface. Radiation occurs across a non-mechanical medium so that there is again no friction and no maintenance to keep a constant mechanical condition is required. Equipment to measure the temperature of the source of these radiations based on optical methods of collection and focussing and spectral analysis are expensive and not appropriate for multiple industrial use. Methods which sum the radiant energy over a solid angle and convert it to another form of energy which is amenable to measurement are subject to loss errors which may be variable.  
  It is an object of this invention to reduce the variable heat equilibrium of a simple radiant heat collector that is adaptable for use with a rotating heated surface.  
  According to the present invention, there is provided means for transferring heat to a rapidly moving filament comprising a roller, endless belt or the like conveying element, means for mounting the conveying element on a frame of a filament processing machine, a heating source adapted for mounting on the machine frame for supplying heat to a surface of the conveyingelement which, in use, contacts the filament, a recess formed in a side edge of the conveying element which, 1  
 in use, is adjacent to the frame, the recess extending adjacent to and parallel with the filament contacting surface of the element, and a temperature sensor for extending into the recess without contacting the side walls thereof, wherein the temperature sensor is mounted in good thermal contact with a structure having a substantial area extending into radiation from the side walls of the recess, the structure is supported from an intermediate support which is in good thermal contact with the ambient atmosphere, there being a high thermal resistance between the intermediate support and the structure, and supports of high thermal re sistance are provided for mounting the intermediate support on the frame of the machine.  
  The intermediate support may also carry electrically insulated connections for any electrical connections between the temperature sensor and frame related measuring and/or control equipment.  
  The invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
  HO. 1 is an axial section of heat transferring means according to the invention;  
  FIG. 2 is a detail of the mounting of a temperature sensor in the heat transferring means of FIG. 1; and  
  FIGS. 3A and 3B show schematically temperature and thermal resistance parameters in a known heat transferring means and in the heat transferring means of FIGS. 1 and 2, respectively.  
  Referring now to FIG. 1 of the drawings, a roller 20 is supported from a main frame 1 of a filament processing machine by means ofa rotatable shaft 2. The roller 20 includes an inner hollow cylinder 3 and a coaxial outer cylinder 4 secured together by means of an annular outer face 5. Inner cylinder 3 is securely and concentrically locked to the rotatable shaft 2 by a nut and washer 6.  
  For supplying heat to the outer cylinder of the roller 20 a heat source 7 is supported on the main frame 1 by an intermediate stationary disc 8 and extends into the space between cylinders 3 and 4. Heat source 7 may be an electrical induction winding or a radiant heater which, when energised by alternating current, induces electrical current in the equivalent of a short circuited single turn formed by the outer cylinder 4.  
  At the end of the roller 20 which is adjacent to the frame 1 and disc 8, an annular slot 9 is formed in the cylinder 4. This slot extends axially along the outer cylinder 4 to a location in close proximity to a section of the outer surface of the cylinder whose temperature is typical of the heat transferring surface. A gap 10 which allows for rotation of cylinder 4 relative to disc 8 is made as small as possible so as to minimise the amount of air change in slot 9. This allows the surface of the slot 9 to reach the same or nearly the same temperature as the outer surface of cylinder 4.  
  Projecting into the slot 9 without contacting the cylinder 4 is a temperature sensor 16 which is supported in the manner shown in more detail in FIG. 2 of the drawings. Referring to FIG. 2, a platform 11 which serves as an intermediate support for sensor 16 has a good temperature radiating surface so that it remains at substantially ambient temperature. To further assist in achieving this object the platform 11 is supported on the disc 8 by pillars 12 of high thermal resistance. Between the pillars 12 a slot 13 is cut in the disc 8 and from the platform 11 two supports 14 extend via the slot 13 to a radiant energy pick-up surface 15 which is located within the annular slot 9.  
  Mounted on the pick-up surface 15 is the temperature sensor 16. The surface 15 is modified by slots 17 to give optimum selection between minimum radiation resistance between the surfaces of annular slot 9 and the pick-up surface 15 and maximum conduction resistance to supports 14. Electrical connection between the sensor 16 and insulated connectors 19 on the platform 11 is via electrical connectors I8, which are kept small in diameter and spiralled to increase their length, thereby reducing thermal shunting.  
  In the above embodiment the ratio between the temperature drop from the inner surface of slot 9 to temperature sensor 16 and the temperature drop from the means of FIGS. 1 and 2, whilst FIG. 3A shows these&#39; two parameters at locations in a heat transferring means corresponding to that in FIGS. 1 and 2 except that there is no platform 11, the temperature sensor 16 being supported directly on the machine frame 1.  
  Referring first to FIG. 3A, T represents the temperature of the inner surface of slot 9, which is substantially equal to the temperature of the outer surface of cylinder 4, and hence the surface temperature of a filament as it leaves the roller 20. T is the temperature of the sensor 16, T is the temperature of the machine frame I, R, is the thermal resistance between the inner surface of slot 9 and the sensor 16 and R is the thermal resistance between sensor 16 and the frame 1.  
  The relationship between the three temperatures is then given by:  
 where Rg/R R2 In practice, it is difficult to make R much greater than X R this relationship being indicated in FIG. 3A. Substituting R 10 X R in equation (2) gives,  
 T&#34; 10/11 x TS) 1/11 X T,, 0.090 TS 0.0909 I) The constant factor 10/ I l X T can be allowed for in calibrating the device but there remain errors in the reading of T due to the term 1]]! X T,,. In a case where the mahine warms up through C. there is an error in the reading of T, of l/l l X 30C 2.73C.  
  Referring now to FIG. 38, T represents the temperature of the platform 11, which is interposed between the sensor 6 and the machine frame 1, and T, is the ambient temperature. R is the thermal resistance between the platform 11 and the frame I and R is the thermal resistance between the platform and the surrounding air due to radiation and contact. Since the heat supplied to the heat sink, platform 11, from the inner surface of slot 9 and from the machine frame 1 equals the heat lost from the platform to the ambient air,  
 Also.  
 TM 2/ 1 2 S 1/ l 2 R ,(as in equation (2), above) Substituting the values for R R R and R given in FIG. 38 gives T T I T T With the known transferring means of FIG. 3A it is clear from equation (3) that under conditions where the controlled temperature T is 200C, the ambient temperature starts at 20C. and rises to 25C and the temperature of the machine frame 1 rises by 30C, the temperature of the sensor T starts at l83.6C. rises to l86.3C. on warm up of the machine. and further increases to l86.80 C with the 5C rise in ambient temperature.  
  For the heat transferring means of FIG. 3B, equation (6) shows that the corresponding temperatures recorded by the sensor 16 are 184.5&#34;, l84.7and l85.lC.  
  In practice, a calibration is effected to remove errors under normal conditions, say at T 25C and a rise in T of 30C to 55C. In the case of the known device of FIG. 3A this gives rise to a total error of 3.2C when the machine is started up at an ambient temperature of 20C. The error reduces to 27C when ambient temperature of 25C is reached. In the device of FIG. 3B the total error is 06C at start up, reducing to only 02C at an ambient temperature of 25C.  
  In the heat transferring means of FIGS. 1 and 2 the platform 11 and pick-up surface 15 are made of a high conductivity metal, blackened to enhance its heat radiation properties. The supports 14 are made of metal with a low cross-sectional area, to increase their thermal resistance, or of ceramic material. The pillars 12 are made of ceramic material and are hollow to allow for fixing by screws to the disc 8.  
  It will be appreciated that heat transferring means according to the invention may have an endless band or belt in place of the roller 20 of FIGS. 1 and 2. In this case a slot corresponding to slot 9 may be formed along one lateral edge of the belt to receive a temperature sensor. Preferably, the sensor extends into the slot at a location where the belt contacts a driving roller therefor.  
  For supplying heat to the roller surface or endless band or belt a source of heat radiation may replace the winding 7. Alternatively, slip rings may be employed to supply heating current to the roller, band or belt.  
 I claim:  
 1. An apparatus for transferring heat to a rapidly moving filament comprising:  
 a conveying element having an endless conveying surface;  
 means for mounting said element on a frame of a filament processing machine;  
 a heating source mounted on said frame for supplying heat to a surface of said conveying element which, while in use, contacts said filament;  
 a recess formed in a side edge of said conveying element, adjacent to said frame, said recess extending adjacent and parallel to the surface of said conveying element;  
 a radiant energy pick-up surface disposed within said recess, said surface having substantial area and being exposed to radiation from the side walls of said recess;  
 a temperature sensor mounted in good thermal contact with said pick-up surface and extending into said recess without contacting the sidewalls thereof;  
 intermediate support in good thermal contact with the ambient atmosphere for support of said pick-up surface, said support having a high thermal conductivity and there being a high thermal resistance between said intermediate support and said pickup surface; and  
 support means of high resistance for mounting said intermediate support on the frame of the machine.  
  2. Heat transferring means as claimed in claim 1, wherein the conveying element is a hollow, rotatable roller, and the recess is an annular cylindrical recess formed in a cylindrical side wall of the roller.  
  3. Heat transferring means as claimed in claim 2, wherein the heating source extends into the interior of the hollow roller.  
 &#39; wherein the heating source comprises an electrical winding for inducing heating currents in the conveying element.  
  7. Heat transferring means as claimed in claim 1, wherein the heating source comprises a heating element for supplying radiant heat to the conveying element.