Patent GB-421500-A (GB)
Title: Improvements in methods and apparatus for setting the twist of silk and rayon yarns
IPC: D06M11/05
Filed: 1933-11-30
Abstract: In a method of setting the twist of silk and rayon yarns warm air with a humidity near the saturation point but sufficiently below to avoid any condensation, is rapidly circulated through a quantity of the material in an insulated enclosure provided with heating means, vapour generating means, and means for causing air currents for distributing the vapour within the oven and through the material being treated.  The ovens comprise a casing having outer and inner panels separated by heatinsulating material, the inner lining being of rust-proof alloy.  A fan or blower 16, Fig. 1, is hung in a horizontal plane under the roof 11, <PICT:0421500/IV/1> <PICT:0421500/IV/2> <PICT:0421500/IV/3> and secured to a shaft 17 carrying a pulley 18 connected by a belt 19 with a motor 20.  The blower is enclosed in a casing 21, 22, 23, the portion 21 of which contains scroll-shaped deflectors to distribute the air efficiently down each portion 22.  The ducts 22 are wider at the bottom than the top, and directly beneath their mouths 26 are the electric heaters 28 and vapour generators 32 containing water and immersion heaters.  The air currents pass over the heating elements and are deflected by the cover 34 of the vapour generators past their outlets 35 to mix the air and vapour. A constant level water reservoir outside the oven supplies the vapour generators and the tank 41 of the wet bulb 43 of a hydrometer.  The wet and dry bulbs 43, 44 are connected by tubing 47 with a recording and controlling means 46 connected by leads 49, 50 with a panel box 51.  Wheel tracks 59 with guiding pieces 60 are provided on the floor of the oven to facilitate the loading of a wheeled truck.  The temperature and humidity are controlled automatically by means of a controller 46, Fig. 1 connected through a double-pole switch 69, Fig. 7, with the power lines 65, 66, 71.  From the junction points 90 between the fuses and the motor a control circuit 72, 73 is taken off.  The lead 72 is connected with a contact brush 102 of the dry bulb commutator contact assembly 103 (Fig. 8) of the controller 46.  Expansion of fluid in the dry bulb 44 causes fluid in the tube 47 to expand a bellows and move the lever 103A to rotate the assembly 103.  The lead 72 is similarly connected with the contact brush 104 of the wet bulb assembly 105.  The lead 73 is connected with a coil 106 of the dry bulb relay 107, and the coil 108 of the wet bulb relay 109.  The commutator assembly 103 has three discs 110, 111, and 112, and the assembly 105 is similar.  The lower discs of each assembly are the common contacts and their entire contact surfaces are heavily rolled silver on golding bronze, while the centre and top discs are made of a phenolic condensation product with metallic insets.  The ends of coils 106, 108 are connected to the contact brushes of the lower discs, and the relays 107, 109 have respectively contacts 140, 122 to open or close circuits through contacts 120, 121 or 123, 124.  The contact arms 140, 122 are respectively connected with contact brushes 161, 141, and the contacts 121, 124 are connected with the coils 125, 127 of the relays 126, 128, the other ends of the coils leading to the conductor 73. When the relay 126 is de-energized, current cannot pass through the lines 65A, 66A to the dry heaters 28, and when the relay 128 is open no current flows through the lines 65B, 66B to the immersion heaters 33.  The operation is described in connection with the dry bulb and dry heaters.  The commutator discs, Figs. 7 and 8 rotate as a unit, rising temperature causing rotation in a clockwise direction looking down on the discs.  The three brushes are in the same vertical plane and the "on" and "off" positions are represented by the positions of the edges of the metallic insets on the upper and central discs.  The contacts on each disc are connected through the shaft 103A.  When the temperature is too low and switch 69 is closed, brushes 102, 161 are in contact with their metallic segments 117, 117A.  Current flows from the line 72 through the centre brush 102 and centre commutator to the bottom disc and brush 118 and thence through <PICT:0421500/IV/4> coil 106 to lead 73, thus closing the contact 140, 120, 121, and causing current to flow from conductor 72 through brush 102, shaft 103A contact 117A, contact arm 140, and coil 125 to close switch 129 and circuit 65A, 66A to the heaters 28.  As the temperature increases the commutator discs rotate, and first contact 117, 102 is broken which does not affect the heaters and then the top contact 117A, 161 which switches them off.  As the temperature falls, contact 117A, 161 is first remade without switching on the heaters and then contact 117, 102 to switch them on.  The temperature is set by the dry bulb pointer 83 (Fig. 1).  The pen 85 records the dry temperature.  The wet bulb commutator assembly 105 acts in a precisely similar manner, controlling the relay switch 127 of the immersed heaters 33.  In a modification shown in Fig. 9, the commutator assemblies 103, 105 are dispensed with, and rise in the dry bulb temperature increases the pressure in the bellows 150 actuating a bell-crank lever 152, 153 connected by a link 154 to the contact lever 155A controlled by snap mechanism 155; when the pull exerted by the link 154 is great enough to separate the end 155A of the lever from the magnet 155B the circuit is broken at 157 and the relay 77 is opened and the heaters disconnected.  The sensitivity is adjusted by altering the tension of the spring 158 which exerts a pressure against the lever 152 by turning the adjusting screw 159. The wet bulb temperature is similarly controlled.  A switch 89 in the circuit of the immersion heaters, permits the resistances of the immersion heater to be connected in series or in parallel, or with current flowing only in one resistance or with current in neither resistance.  A supplementary heater 33A may be connected with either the dry or wet heaters by a switch 160, and this heater may also have a switch such as 89.  Thus wide variations of humidity, temperature and the rate of attaining the desired conditions are possible.  When setting the twist in silk and rayon yarns, the temperature and humidity are gradually increased from atmospheric conditions to a maximum temperature between 130 and 200 DEG  F. and preferably between 160 and 170 DEG , and the humidity is increased to a maximum of 50 per cent to 98 per cent and is preferably between 90 per cent and 94 per cent.  The time for this increase is 5 to 60 minutes, the temperature being raised faster than the humidity so that condensation never occurs.  The conditions are maintained for 25 to 60 minutes.  Steam, steam-heated water, gas radiators, or gas operated immersion heaters may be used instead of electricity for heating.