US3632946A

US3632946A - Microwave furnace for continuous heat treating of various pieces of dielectric material

Info

Publication number: US3632946A
Application number: US874341A
Authority: US
Inventors: Joel Henri Auguste Soulier
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-12-05
Filing date: 1969-11-05
Publication date: 1972-01-04
Anticipated expiration: 1989-01-04
Also published as: DE1960338A1; DE1960338B2; ES374191A1; FR1598315A; GB1290888A

Abstract

The furnace comprises a rectangular waveguide for a hyperfrequency wave generator and this waveguide is placed transversally to a tunnel furnace defining a longitudinal corridor, at least one part of said tunnel furnace being formed by two complementary half-shells assembled longitudinally to one another.

Description

Uite States Patent Inventor Joel Henri Auguste Soulier 81 Boulevard Marceau, Colombes, France Appl. No. 874,341 Filed Nov. 5, 1969 Patented Jan. 4, 1972 Priority Dec. 5, 1968 France 176804 MICROWAVE FURNACE FOR CONTINUOUS HEAT TREATING OF VARIOUS PIECES OF DIELECTRIC MATERIAL 9 Claims, 7 Drawing Figs.

US. Cl 219/1055 Int. Cl 1105b 9/06 Field ofSearch 219/10.55

Primary Examiner-.1. V. Truhe Assistant Examinerl-lugh D. Jaeger Attorney-Irving M. Weiner ABSTRACT: The furnace comprises a rectangular waveguide for a hyperfrequency wave generator and this waveguide is placed transversally to a tunnel furnace defining a longitudinal corridor, at least one part of said tunnel furnace being formed by two complementary half-shells assembled longitudinally to one another.

PATENTEU JAN 4 B72 SHEET 1 UF 2 m FL Pic-11.5.

Pia-4 PATENTED JAN 4:972

SHEET 2 ,UF 2

Junnu MICROWAVE FURNACE FOR CONTINUOUS HEAT TREATING OF VARIOUS PIECES OF DIELECTRIC MATERIAL The present invention relates to a microwave furnace, i.e., a furnace making use of hyperfrequency waves for treating absorbent dielectric materials, such as rubber and its derivatives.

The invention more particularly concerns a furnace enabling the heat treatment of strips or pieces of dielectric material of various sections produced, for instance, at the exit of a slubbing machine.

Up till now, the heating of such pieces by means of microwaves has come up against very great difficulties. Actually for enabling the heat treatment of a piece, such as a joint for a car body, it is necessary, on account of the speed at which slubbing machines work, to provide relatively long furnaces, or even a succession of several furnaces one behind the other; an added problem in to make it possible to hold the piece for treatment in a rigorous position in the cavity of the furnace. Also any dissipation towards the outside of hyperfrequency waves, which might be dangerous for workers, must be prevented.

Furthermore, the heat treatment undergone by the piece in the furnace has the effect of giving off fumes and vapors, which deposit on the inner wall of the furnace. This has the effect, after a certain time, of making the walls of the furnace absorbent, and consequently, greatly altering the characteristics of the work. This is compounded because a furnace of great length is obviously difficult to clean, or else necessitates taking down and rebuilding by experts who must be capable or again regulating the furnace.

The present invention completely solves the difficulties hitherto met in creating a new microwave furnace.

According to the invention, the furnace comprises a rectangular wave guide for a hyperfrequency wave generator and this wave guide is placed transversely to a tunnel furnace defining a longitudinal corridor, at least part of the tunnel furnace being made of two complementary half-shells assembled longitudinally to one another.

Various other characteristics of the invention will moreover be revealed by the detailed description which follows.

An embodiment of the invention is shown, by way of nonrestrictive example, in the accompanying drawings.

FIG. 1 is an elevation-section of the microwave furnace of the invention.

FIG. 2 is a plane view seen from above partially cut away along the line II-II of FIG. 1 of this furnace.

FIG. 3 is a section taken along the line III-III of FIG. 1.

FIG. 4 is a section taken along the line lV-IV of FIG. 1.

FIG. 5 is a section taken along the line VV of FIG. 1.

FIG. 6 is a section taken along the line VI-VI of FIG. 1.

FIG. 7 is a section taken along the line VII-VII of FIG. 1.

The furnace shown in the drawing for the continuous heat treatment of dielectric materials, particularly rubber in the shape of pieces formed by a slubbing machine, is supported by a frame 1 which is made, for instance, by means of tubes or other iron bars. Their particular arrangement has little importance with regard to the invention, because this frame has simply the function of supporting the assembly of members of the furnace and means which are associated with it.

At its ends, the frame 1 is provided with sets of cheeks 2, 2a, of which at least one set, in this case the set of checks 2 seen at the left part of FIG. 1, is provided with guiding slides 3 for the slides 4 supporting a spindle 5 on which a wheel 6 can revolve. Screws 7 are provided for moving the slides 4 so as to correlatively move the wheel 6 which fonns a tightening wheel for an endless belt of a conveyor 8. This conveyor 8 is also supported by a second wheel 60 mounted between the cheeks 2aand whose shaft is associated with a driving device (not shown). Thus the conveyor 8 is continuously movable at a regular speed, but may be regulated necessary to hold the product for treatment as supported by the conveyor 8 for a more or less long time in the furnace.

The furnace itself comprises a main body 9, comprising as shown in particular in FIGS. 3 and 4, a sole-plate 10 from which a semicylindrical half-shell 11 is made, extended by longitudinal

lateral edges

12, 12a.

At its end 9a the body 9 defines a cylindrical portion clearly shown in FIG. I, this portion fonning a clamp for fixing a waveguide 13 of rectangular section. The body 9 supports a second semicylindrical half-shell 14, also having lateral and

longitudinal edges

15, 15a complementary to the

edges

12, 12a and applied on the previous edges by means, on the one hand, of seal-tight washers I6, and on the other hand, of washer 17 of metal braid as shown in FIG. 4 for preventing any outward propagation towards the outside of hyperfrequency waves circulating in the furnace, as explained in what follows.

Although it can be fixed in other ways, the half-shell I4 is advantageously articulated on spindles 18 carried in supports 19 formed by the body 9, laterally in relation to the body as shown in FIGS. 2 and 4. Articulated threaded rods 20 are provided on the other lateral side of the body with tightening screws 21 bearing on the branches of flanges made on the rim 15 of the half-shell 14.

FIG. 1 shows that the assembly of the body 9 and half-shell I4 defines a tubular corridor 22 of circular section having the same diameter as the cylindrical part 9a of the end of said body 9.

A cylindrical passage or casing 23, of the same diameter as the corridor 22, is fixed on the waveguide 13 in the extension of said corridor 22. This passage or casing 23 acts as housing for a piston 24 provided with segments 25 of metal braid, the piston being able to slide in the nozzle or casing 23, which for this purpose, has slots 26 as shown in FIG. 2 into which pass locking screws 27. The piston 24 is intended, when it is moved, to enable the tuning of the wavelength in the guide 13 and the distribution of the calorific power developed in the vicinity of the intersection of the waveguide and corridor 22 of the fumace, at the same time permitting adaption of the magnetron which is the microwaves generator, said magnetron being mounted on the waveguide by an end piece 28.

For tuning the wavelength in the furnace the waveguide 13 is provided as shown in FIGS. 1 and 7 with a resonator 29 placed at the top part of said waveguide and supported by a core 30. The care 30 is movable axially, under the guidance of gudgeons 31 by means of a screw 32 which is in turn controlled by a milled knob 33. This knob 33 is placed in a slot 34 defined inside a cover 35 closing the top part of the waveguide 13. The resonator 29 is, as shown in FIG. 7, formed by a kind of metal case reflecting the hyperfrequency waves.

The tunnel-furnace unit described above and formed by the body 9, the half-shell 14 forming a cover, the waveguide 13 and the passage or casing 23, is supported, as shown in FIGS. I and 6, so as to be able to be adjusted for height. To this end, a plate 36 is provided which is directly carried by the frame I and which, at both ends, supports jacks designated on the whole by 37 and 38 in FIG. 1, of which jacks an embodiment is shown in FIG. 6. These jacks comprise a tubular cover 39 fonning wings 40 by which said cover is connected to the plate 36 by means of crossbars 41. The cover 39 contains a bearing 42 inside for a pin 43 whose cut end 434 penetrates into the sole-piece 10 of the body 9 of the furnace. A bearing flange 44 made integral with the pin 43 is fixed on the body 9 by a screw 45 so as to prevent any rotation of the pin 43 which has a threaded portion 42a underneath its part arranged in the bearing 42, on a portion which a tapped chain wheel 46 is screwed. The chain wheel 46 is securely held between the bearing 42 and cover 47 fixed on the underneath of the cover 39, said cover 47 being tranversed by a threaded stem 43b of the pin 43, on which a lock nut 48 is fixed.

As shown in FIG. 1, the chain wheels 46 of the two

jacks

37 and 38 are held together by a chain 49 constantly tightened by a spring 50, this chain comprising an operating handle 51 forming a pointer 51a moving in front of graduations carried by a scale 52 fixed on the frame 1.

From the foregoing, one sees that by moving the handle 51, the chain wheels 46 are revolved of the two jacks whose threading axially drives, in a rising or descending direction,

the pins 43 of said two jacks, and then, the furnace unit described above, is correlatively raised or lowered.

The plate 36, supporting the jacks described above, also supports pistons 53 clearly visible in FIG. 3, which are provided with braided metal washers 54 and sealtight washers $5 for bearing in cylindrical housings provided in the sole-piece of the body 9 so that said pistons project inside the corridor or cavity 22 of the furnace. The pistons 53 are extended by forks 56 acting as support and guide for the conveyor 8 formed by a cloth of material permeable to hyperfrequency waves, for instance, glass fabric coated with silicon- The guiding forks 56 of the cloth being relatively close to each other, one is assured that this cloth does not sag in any manner inside the furnace cavity, which enables one to make certain that the heat-treated object, the rubber piece 57, for instance, shown in FlZGS. 3 and 4, is always properly maintained in the axis of the furnace, so that it is uniformly treated.

According to the particular shape assumed by the piece 57 for treatment and also according to its cross section dimension, it is obviously necessary to regulate the position of the conveyor 8 in relation to the longitudinal axis of the tunnel or cavity 22, which is done as explained in the foregoing, by causing the furnace to rise or descend, whose position is repeated in relation to that of the conveyor, which is fixed for height, by means of the pointer 51a of the operating handle 51.

So that the hyperfrequency waves produced in the furnace cavity cannot propagate outside the cavity, there is provided in the tuning piston 24 containing the passage or casing 23, an opening 24a whose cross section shape is as close as possible to that of the piece for treatment. Furthermore, this piston is advantageoulsy made of material absorbing hyperfrequency waves, carbon for instance, and in like manner, the opposite end of the cavity 22 is provided with a plug 58, preferably of carbon, which is provided with a sealtight washer 59 and a metal braid washer 60. This plug is obviously hollow to enable the passage of the conveyor 8 and piece 57 and is provided on its part projecting beyond the cavity 22 with a perforated cover 61 for holding a movable register 62 acting both for guiding the conveyor 8 and closing said plug 58 as completely as possible.

In addition to the members described in the foregoing, the furnace comprises, inside the tunnel or cavity 22, annular rings 63 which are placed in the part of half-shell cavity 22 defined by the body 9 and half-shell 14. These annular rings, which are quite thin, for instance, 5 to 6/10ths of a millimeters have a width depending on the wavelength produced by the magnetron. Additionally they are separated from each other, as shown in FIG. 1, by a distance d corresponding to half the wavelengths produced, so the electric field set up in the furnace cavity tends to close, as shown at 64 in FIG. 1 around the successive rings. Thus the magnetic field shown by dots is contained inside the volume defined by each ring.

One sees in FIG. 4 that inside of the rings the electric field 64 is thus developed radially from the axis of the cavity 22, whereas the magnetic field, designated by 65 remains annular and concentric to said rings inside said rings.

Supplementarily, one provides level with the waveguide 13, a sleeve 66 of material permeable to hyperfrequency waves, for instance, of tetrafluoroethylene, this sleeve being keyed at the mounting, so that the magnetic field properly closes inside the copper rings 63. The sleeve 66 also has the function of preventing smoke or vapors coming with the heating of the piece 57 from penetrating into the waveguide 13. By making the sleeve 66 more or less slide, the position of the wave phase is actually regulated.

As can be seen from the foregoing, the various constitutive parts of the furnace, namely, principally the body 9 and halfshell 14 forming its cover, likewise the passage or casing 23 as well as the wave guide 13, are made of material reflecting hyperfrequency waves, and for instance, of light alloy, so that these parts can easily be made by moulding and machining. Since the half-shell 14 acting as a cover is easily removed, and since the rings 63 in which the magnetic field is enclosed are spaced apart in relation to each other it is possible to clean the inside of the furnace without any taking down. Moreover, the piston 24 and likewise the plug 58 can also be made, although this is not shown in the drawings, of two complementary halfshells, so that these parts, can, if so desired, be changed when it is necessary to treat a piece of another shape, this change thus being carried out without needing to take the conveyor 8 down.

The invention is not restricted to the embodiment shown and described in detail, for other modifications can be applied to it without going outside its scope.

I claim:

1. Microwave furnace for the continuous heat treatment of various pieces of dielectric materials comprising:

a hyperfrequency wave generator,

a tunnel furnace defining a longitudinal corridor, one part of said tunnel furnace being made by two complementary half-shells assembled longitudinally to each other,

a waveguide connected to said generator and transversely to the tunnel furnace whereby hyperfrequency waves are transmitted along said tunnel furnace, and

a sleeve inserted in the tunnel furnace, at its junction with the rectangular guide, this sleeve being made of material penneable to hyperfrequency waves and being mounted for being axially regulated for adjusting the wave phase in the waveguide and preventing the propagating of smoke and vapors in the waveguide.

2. Microwave furnace for the continuous heat treatment of various pieces of dielectric materials comprising:

a hyperfrequency wave generator,

tunnel furnace defining a longitudinal corridor, one part of said tunnel furnace being made by two complementary half-shells assembled longitudinally to each other,

a waveguide connected to said generator and transversely to the tunnel furnace whereby hyperfrequency waves are transmitted along said tunnel furnace,

said tunnel furnace containing continuous walled rings and a belt of an endless conveyor, and

supports within said tunnel furnace and projecting between said rings for guiding the belt of said endless conveyor, said supports projecting from pistons traversing the wall of the tunnel furnace, said pistons being joined together and means being provided for regulating the mutual position of the tunnel furnace in relation to the pistons, so that the position of the conveyor belt is adjustable inside said tunnel furnace.

3. Microwave furnace as claimed in claim 2 in which the pistons are rigidly fixed on a plate which is carried by a frame and the tunnel furnace assembly is connected to said frame by means of at least one jack, so that the regulating of the position of the conveyor belt in relation to said tunnel furnace is done by moving said tunnel furnace.

4. Microwave fumace for the continuous heat treatment of various pieces of dielectric materials comprising:

a hyperfrequency wave generator,

a tunnel fumace defining a longitudinal corridor, one part of said tunnel furnace being made by two complementary half-shells assembled longitudinally to each other,

braided metal washers between each of the tunnel furnace parts for preventing the propagation towards the exterior of the electric field produced in the tunnel furnace.

5. Microwave furnace for the continuous heat treatment of various pieces of dielectric materials, comprising:

a hyperfrequency wave generator;

a tunnel fumace defining a longitudinal corridor;

one part of said tunnel furnace being made by two complementary half-shells removably assembled longitudinally together along two longitudinal joints;

a waveguide connected to said generator and transversally to said tunnel furnace whereby hyperfrequency waves are transmitted along said tunnel furnace;

said tunnel furnace further containing at least in its part formed by said two complementary half-shells, continuous walled conducting rings which are spaced apart by a distance substantially equal to a half-wavelength of the hyperfrequency waves developed in the volume of said tunnel furnace by said generator whereby electric fields which are generated may close inside said rings despite joints between said complementary half-shells.

6. Microwave furnace as claimed in claim 5 in which:

said tunnel furnace contains a belt of an endless belt conveyor for holding a piece of dielective material to be heattreated;

said conveyor is made of a material permeable to hyperfrequency waves, particularly of glass fabric coated with silicon;

and said belt is carried inside said tunnel furnace by adjustable supports located to project between said continuous walled conducting rings.

7. Microwave furnace characterized substantially in ac cordance with claim 5, wherein a sleeve is inserted in said tunnel furnace at its junction with said waveguide, said sleeve being made of a material which is permeable to hyperfrequency waves and which is mounted for being axially regulated for adjusting the wave phase in said waveguide and preventing the propagating of smoke and vapors in said waveguide.

8. Microwave furnace characterized substantially in accordance with claim 6, wherein said supports for said belt project from pistons traversing the wall of said tunnel furnace, said pistons being joined together and means being provided for regulating the mutual position of said tunnel furnace in relation to said pistons so that the position of said belt is adjustable inside said tunnel furnace.

9. Microwave furnace characterized substantially in accordance with claim 8, wherein said pistons are rigidly fixed on a plate which is carried by a frame, and said tunnel furnace assembly is connected to said frame by means of at least one jack so that the regulating of the position of the belt in relation to said tunnel furnace is accomplished by moving said tunnel furnace.

Claims

1. Microwave furnace for the continuous heat treatment of various pieces of dielectric materials comprising: a hyperfrequency wave generator, a tunnel furnace defining a longitudinal corridor, one part of said tunnel furnace being made by two complementary half-shells assembled longitudinally to each other, a waveguide connected to said generator and transversely to the tunnel furnace whereby hyperfrequency waves are transmitted along said tunnel furnace, and a sleeve inserted in the tunnel furnace, at its junction with the rectangular guide, this sleeve being made of material permeable to hyperfrequency waves and being mounted for being axially regulated for adjusting the wave phase in the waveguide and preventing the propagating of smoke and vapors in the waveguide.

2. Microwave furnace for the continuous heat treatment of various pieces of dielectric materials comprising: a hyperfrequency wave generator, a tunnel furnace defining a longitudinal corridor, one part of said tunnel furnace being made by two complementary half-shells assembled longitudinally to each other, a waveguide connected to said generator and transversely to the tunnel furnace whereby hyperfrequency waves are transmitted along said tunnel furnace, said tunnel furnace containing continuous walled rings and a belt of an endless conveyor, and supports within said tunnel furnace and projecting between said rings for guiding the belt of said endless conveyor, said supports projecting from pistons traversing the wall of the tunnel furnace, sAid pistons being joined together and means being provided for regulating the mutual position of the tunnel furnace in relation to the pistons, so that the position of the conveyor belt is adjustable inside said tunnel furnace.

4. Microwave furnace for the continuous heat treatment of various pieces of dielectric materials comprising: a hyperfrequency wave generator, a tunnel furnace defining a longitudinal corridor, one part of said tunnel furnace being made by two complementary half-shells assembled longitudinally to each other, a waveguide connected to said generator and transversely to the tunnel furnace whereby hyperfrequency waves are transmitted along said tunnel furnace, and braided metal washers between each of the tunnel furnace parts for preventing the propagation towards the exterior of the electric field produced in the tunnel furnace.

5. Microwave furnace for the continuous heat treatment of various pieces of dielectric materials, comprising: a hyperfrequency wave generator; a tunnel furnace defining a longitudinal corridor; one part of said tunnel furnace being made by two complementary half-shells removably assembled longitudinally together along two longitudinal joints; a waveguide connected to said generator and transversally to said tunnel furnace whereby hyperfrequency waves are transmitted along said tunnel furnace; said tunnel furnace further containing at least in its part formed by said two complementary half-shells, continuous walled conducting rings which are spaced apart by a distance substantially equal to a half-wavelength of the hyperfrequency waves developed in the volume of said tunnel furnace by said generator whereby electric fields which are generated may close inside said rings despite joints between said complementary half-shells.

6. Microwave furnace as claimed in claim 5 in which: said tunnel furnace contains a belt of an endless belt conveyor for holding a piece of dielective material to be heat-treated; said conveyor is made of a material permeable to hyperfrequency waves, particularly of glass fabric coated with silicon; and said belt is carried inside said tunnel furnace by adjustable supports located to project between said continuous walled conducting rings.

7. Microwave furnace characterized substantially in accordance with claim 5, wherein a sleeve is inserted in said tunnel furnace at its junction with said waveguide, said sleeve being made of a material which is permeable to hyperfrequency waves and which is mounted for being axially regulated for adjusting the wave phase in said waveguide and preventing the propagating of smoke and vapors in said waveguide.