US3385953A - Heater for extrusion press container - Google Patents

Description

y 28, 1958 c. v. HENNEBERGER 3,385,953

I HEATER FOR EXTRUSION PRESS CONTAINER Filed Sept. 29, 1965 2 Sheets-Sheet 1 INVENTOR. CHARLES V HENNEBERGER ATTORNEY May 28, 1968 c. v. HENNEBERGER HEATER FOR EXTRUSION PRESS CONTAINER 2 Sheets-Sheet Filed Sept. 29, 1965 3 2 5 8 I 8 0 7 8 5 0 8 4 l? 8 T 8 i i 0 J .1 a 5 MW 7 w 61H) q J v I6 m 1 3 3 6 m I q 5 2 5 2 6 W 8 3 3 4 6 4 $3 I 3 5 2 m) M 2M 2 0 7 v 5, 6L 2 7 6 5 5 7 6 5 3 W 21 l 6 7 1 7 FIG. 3

ATTORNEY United States Patent 3,385,953 HEATER FOR EXTRUSION PRESS CONTAINER Charles V. Henrieberger, Pentield, N.Y., assignor to Farrel Corporation, Rochester, N.Y., a corporation of Connecticut Filed Sept. 29, 1965, Ser. No. 491,118 3 Claims. (Cl. 219390) ABSTRACT OF THE DISCLQSURE Three electrical heating elements are mounted in serpentine fashion in each of a pair of confronting, arcuate recesses formed in a pair of separable housing sections, which surround an annular billet container. The elements are connected in delta to a three phase power source, and

are controlled by a pair of solenoid Operated switches controlled in turn by a thermocouple. When the temperature of the container reaches a first value, one of the switches opens to halve the voltage across the elements; and when said temperature exceeds a second value above the first, the second switch opens to deenergize the elements until the temperature falls below said second value.

This invention relates to extrusion presses, and more particularly to electric, radiant heating of the billet containers of metal extrusion presses.

Heretofore electric radiant heating of extrusion press containers has usually been accomplished by applying three-phase power to the heater load through a threepole contactor controlled by a temperature controller instrument and thermocouple. This results in a full power On-Off type of operation. The surges of power at full voltage, however, contribute to a shortened heater life by subjecting the resistance wires of the heater coils and the surrounding heater sheaths, to extremely wide temperature variations over relatively short periods of time.

A further disadvantage of such prior container heaters is that each heater is usually made of a plurality of short heater elements connected in series with their connection points located in a zone of high ambient temperature. The points of mechanical connection become weak points in the series heater system, and the connections tend to loosen through temperature cycling.

An object of this invention is to provide an improved container heater, which will have a substantially longer operating life than prior billet heaters of the type described. To this end a major object of this invention is to provide an improved container heater in which extreme surges of power are substantially eliminated, thereby substantially increasing the operating life of the heater. To this end too, an object of the invention is to provide an electric radiant heating system for extrusion press containers in which the heaters will operate without extreme changes in wire and sheath temperatures over the greater part of any standard length operating cycle. To this end also it is an object of this invention to provide an improved container heater in which a majority of the connection points, that are subject to high ambient temperatures in conventional heaters are eliminated.

Another object of this invention is to provide an improved container heater which for the most part utilizes standard, readily available components, thereby minimizing manufacturing costs.

A still further object of this invention is to provide an improved container heater, which is far more efficient than prior heaters of this type.

Still another object of the invention is to provide a heater for the containers of extrusion presses in which the power consumption can be materially reduced as compared with conventional such heaters.

Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.

In the drawings:

FIG. 1 is a vertical section through a billet container and housing equipped with a heater made in accordance with one embodiment of this invention;

FIG. 2 is a plan view of this housing with part of the upper section of the housing cut away to illustrate portions of the heater; and

FIG. 3 is a wiring diagram illustrating one manner in which this heater may be wired.

Referring now to the drawings by numerals of reference, and first to FIGS. 1 and 2, 11 designates a container housing comprising upper and lower sections 12 and 13, which are removably secured to one another by bolts 14. The housing sections 12 and 13 have integral bearing portions at both ends, which are denoted 17 and 18, respectively. Removably secured between the sections 12 and 13 and seated on the bearing portions 17 and 18 is the billet container 16. Keys 15, which engage in aligned slots in the container and in the bearing portions 18, serve to hold the container against rotation in the housing.

Intermediate their bearing portions the sections 12 and 13 accommodate arcuate- shaped heater coils 21 and 22, respectively. These coils 21 and 22 are mounted in their respective sections 12 and 13 on metal clips 23, which are secured to arcuate insulating blocks 24 that are fastened, in turn, to the respective sections by studs 20.

Coil 21 comprises a plurality (three in the embodiment illustrated) of electric heater elements 25, 26 and 27, each of which extends transversely of the container, and in addition to being curved coaxially with the con tainer, is Wound back and forth several times in opposite directions intermediate its ends to form a plurality of legs (six in the embodiment illustrated). In one side thereof, the left side as illustrated, the upper housing section 12 has therethrough a plurality of spaced ports or openings 28, 29, 30 and 31. Opposite ends -1 and 25-2 of element 25 project out of the openings 28 and 29, respectively; opposite ends 26-1 and 26-2 of element 26 project out of the openings 29 and 30, respectively; and opposite ends 27-1 and 27-2 of element 27 project out of the openings 30 and 31, respectively. These ends 25-1, 25-2, 26-1, 26-2, 27-1 and 27-2 are connected through a flexible conduit and plug (not illustrated) removably to a nearby circuit box, where they are Wired in a circuit which will be described in more detail below.

Coil 22 in the lower section 13 also comprises three heater elements 35, 36 and 37 (FIG. 3), and in plan view constitutes substantially a mirror image of the coil 21 illustrated in FIG. 2. As in the case of coil 21, opposite ends -1 and 35-2 (FIG. 3) of the element 35, opposite ends 36-1 and 36-2 (FIG. 3) of element 36, and opposite ends 37-1 and 37-2 (FIG. 3) of element 37 extend through four ports in the left side of the lower housing section 13, and are connected to the elements 25, 26 and 27 of coil 21 in the manner below described.

At the above-noted circuit box, the heater element ends 25-1 and 35-1 are connected to one another as at 48 (FIG. 3); 35-2 and 26-1 are connected at 49; 26-2 and 36-1 are connected at 50; and 36-2 and 27-1 are connected at 51; 27-2 and 37-1 are connected at 52; and 37-2 and 25-2 are connected at 53. Mounted in the circuit box are two, three pole switches 61 and 62, each of which has three normally closed contacts 63, 64 and 65; and 66, 67 and 68, respectively. Terminals 51, 49, and 53 are connected to one side of the contacts 63, 64 and 65, respectively, by lines 54, 55 and 56. The opposite sides of the contacts 63, 64 and 65 are connected by lines 71,

72 and 73, respectively, to lines 74, 75 and 76, which in turn are connected through a manually operable, three pole On-Off switch 7'7 to a three phase alternating current power source. Terminals 48, 50 and 52 are connected by wires 57, 58 and 59 to one side of the contacts 66, 67 and 68, respectively. The opposite sides of these contacts are connected by lines 78, 79 and 88, respectively, to the lines 74, 76 and 75, respectively.

Lines 75 and 76 are also connected to the input side of a control transformer illustrated schematically at T. The output of transformer T is connected to the input of a conventional thermocouple-responsive, temperature control instrument 82 of the type known, for example, as West Model JPT-3 Temperature Controller. Controller 82 is wired to a thermocouple 83 which is mounted in a heat sink 91 formed in the upper housing section 12, to be responsive to the temperature of the container 16. The controller 82 has two set points, and is capable of providing two different outputs, viz., energizing two different circuits 84 and 85, respectively, as the temperature of the container exceeds first and second values, respectively. The two different outputs, or circuits 84 and 85, of the controller 82 control the operation of the switches 61 and 62, as for example, by solenoids 86 and 87, respectively, which, when energized, open the contacts of switches 61 and 62.

In use the heater coils 21 and 22 maintain the temperature of the container at a predetermined level during the operation of the press. This temperature level will depend upon the material that is to be extruded by the press.

For purposes of explanation, it will be assumed that the controller 82 is set to energize circuit 84, hence solenoid 86, when the thermocouple 83 indicates that the container temperature has reached or exceeded 1000 F.; and it is set to energize circuit 85, hence solenoid 87, when the container temperature reaches or exceeds 1200 F.

When switch 77 is closed, voltage is applied across the heater elements 25, 26, 27, 35, 36 and 37 through the normally closed contacts of the switches 61 and 62. Since full power is thus applied to the heater coils the temperature of the container 16 rises rapidly to 1000 F. When the temperature reaches 1000 F., solenoid 86 is energized through controller 82 to open contacts 63, 64, and 65 of switch 61. Power is now supplied to the heater elements solely through switch 62, at terminals 48, 50 and 52. Hence the heater co-ils now operate at half voltage, and quarter power. When the temperature of the container reaches 1200 F., controller 82 causes solenoid 87 to be energized opening contacts 66, 67 and 68. This cuts off all power from the heater coils until the temperature of the container 16 falls below 1200 F., at which time solenoid 87 is deenergized and switch 62 once again closes. When the container temperature once again reaches 1200 F., the switch 62 once again opens to deenergize coils 21 and 22.

As long as the press is in operation, the heater coils 21 and 22 cycle on and off at one half voltage and quarter power to maintain the container 16 at its elevated temperature level-i.e., between 1000 F. and 1200 F. When the press is shut down, the manually operated switch 77 is moved to its open position. As the temperature of the container drops to room temperature, both switches 61 and 62 return to their normally closed positions.

From the foregoing it will be apparent that the novel container heaters described herein are subjected to full power and full voltage only upon closing of switch 77, and that during most of the time that the press is in operation, the heater coils 21 and 22 cycle on and off at half voltage and quaiter power. Unlike prior heater elements, which are usually operated at full-on or full-off power, heater coils 21 and 22 are seldom subjected to extreme variations in temperatures which accompany such full power on, full power off, type of operation. As a result the invention contributes to a substantially longer heater life.

Moreover, each heater element 25, 26, 27, 35, 36 and 37 within the housing is one integral element wound back and foith upon itself several times, and does not comprise several separate legs mechanically connected to one another as in prior heaters. Each element 25, 26, 27, 35, 36, 37, moreover, has its ends extending out of the housing 11, and connected in circuit with one another at the exterior of the housing, so that the connections are not subjected to the variations in temperature within the housing that would tend to loosen them. Also, since the heater coils 21 and 22 are mounted in the housing 11 rather than in the container, there is no need to substitute heater coils when changing containers. Furthermore, the use of the two control switches 61 and 62 in addition to contributing to longer heater life, increases the control sensitivity and stability of the heater system, as well as substantially reducing the total power consumption needed to operate the heaters, as compared to prior devices. This reduction in total power consumption can amount to approximately 25% over a representative hour period. In addition, since the elements 25-27 in the upper housing section 12 are removably connected by a plug to the circuit box, section 12 can be easily removed from section 13 for removing a container 16 or repairing the coils 21 and 22.

While the invention has been described in connection with a specific embodiment thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. In an extrusion press having a billet container, and a housing surrounding said container, billet heating apparatus, comprising (a) a plurality of electrical heater elements mounted in said housing and operative, when energized, to heat said container, and

(b) circuit means for connecting said elements to a source of electrical power, including (1) a first pair of switches movable between open and closed positions, respectively,

(2) a third switch manualy operable from an open to a closed position to connect said elements to said source to apply full voltage therefrom across each of said elements, when each of said first pair of switches is in one of its two positions, and to apply less than said full voltage across each of said elements, when one of said first pair of switches is in the other of its two positions, and to disconnect said elements from said power source, when each of said first pair of switches is in the other of its two positions, and

(3) means responsive to the temperature of said container to move said one switch to said other of its two positions, when said temperature exceeds a first predetermined value, and to move the other of said first pair of switches to said other of its two positions, when, and only as long as said temperature exceeds a second value, which is above said first value.

2. An extrusion press as defined in claim 1, wherein the last-named means comprises (a) a pair of solenoids which are operative, when energized, to move said first pair of switches from said one to said other positions,

(b) a thermocouple mounted in said housing adjacent said container, and

(0) means connecting said thermocouple to said solenoids, and operative to energize one of said solenoids, when said temperature exceeds said first values, and to energize the other of said solenoids, when said tempearture exceeds said second value.

3. In an extrusion press as defined in claim 2, wherein (a) said means connecting said thermocouple to said solenoids deenergizes said other solenoid, when said temperature falls below said second value, and

(b) said other switch comprises a normally closed switch which recloses, when said other solenoid is deenergized, thereby reenergizing said elements at less than said full voltage thereby reheating said container before the temperature thereof falls below said first value.

References Cited UNITED STATES PATENTS 8/1924 Otis 13-24 1/1935 Jewett 1324 X 4/1958 Van Riper 219-507 X 1/1964 Nelson 18-12 8/1964 Allen 72253 12/1964 Haverkarnp et a1. 72--253 X 8/1965 Muller 72272 X 5/1967 Stroup et al. 1812 FOREIGN PATENTS 12/ 1959 Great Britain.

15 RICHARD M. WOOD, Primary Examiner.

C. L. ALBRITTON, Assistant Examiner.

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