JPS58123827A - Billet heating furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A gas-fired furnace for heating metal billets in preparation for hot forming operations, developed primarily for the purpose of heating positive billets prior to stamping in a press. .

Automated presses in the plus stamping industry require regular feeding of billets at substantially uniform stamping temperatures. And for this purpose, the billet is placed on a train, which is pushed step by step through the furnace by a feeding mechanism.
n) to the press, where the feed mechanism typically adds the billet to the rear of the train in synchronization with the positive stamping rate. Although the furnace is intended to heat each billet to the required punching temperature as it passes through the furnace, the furnaces used in the past have not been found to be completely satisfactory. Didn't prove it.

In one type of furnace that has been used, a train of billets is pushed along a refractory casting skid at the pace of a figure-7 refractory platform, and down one side of it is a line of pneumatic plast gas. A burner nozzle blows the flame onto the billet on the skid. This open hearth furnace has a very low thermal efficiency and if the train of billets through the furnace stops for any reason, e.g. due to a press stoppage, the high heat capacity of the skid and refractory platform Therefore, a problem may arise that the billet melts.

Additionally, the furnace controls are primarily manual, requiring frequent attention and creating a poor working environment due to flame splash from the skid.

In another type of conventionally used gas-fired furnace, known as an enclosed skid type, the train of billets is attached to a skid that extends through an enclosed furnace chamber lined with a refractory material. be moved along. In this type and in existing furnaces, the lining is made of a refractory material and, because of its high thermal mass, has a tendency to melt the billets during cessation of billet flow through the furnace if the operating temperature of the furnace is too high. There is electricity. To avoid this problem, the furnace is controlled so that the operating temperature is maintained below the melting point of the billet, but just above the stamping temperature. However, this method of operation is inefficient. The reason is that the temperature difference between the billet at the exposed end of the furnace and the furnace is very small, so the heat transfer coefficient is very low. Therefore, the furnace needs to be relatively large.

It is an object of the present invention to provide an enclosed skid billet furnace that can be made very small and yet operate safer, more reliable and more efficiently than existing enclosed skid billet furnaces. It is.

This eye. For purposes of this invention, an enclosed skid-type furnace for heating a billet to a predetermined temperature below its melting point when the billet is moved through a furnace chamber through a skid at a predetermined rate, a billet feeding mechanism adjacent to the inlet end of the furnace chamber for regularly feeding the billets upward along the skid; and a gas burner for raising the temperature inside the furnace chamber to an operating temperature higher than the melting point of the billets. a burner control means for maintaining the operating temperature substantially constant; a feed path extending adjacent the outlet end of the furnace chamber for receiving billets as they leave the furnace chamber; billet detectors arranged to detect interruptions in the regular flow of the burner and to cause the burner to shut down when such interruptions are detected;
a retract mechanism for activating to deflect the billet from the feed path if the burner is shut down;
The thermal mass of the skid and the refractory lining of the furnace chamber are
This includes being such that the temperature within the furnace chamber falls below the melting point of the billets before any billets stagnant within the furnace chamber can rise to the melting point.

By using a lightweight, heat-resistant skid and a low thermal mass lining in the furnace chamber, and arranging the burners to immediately shut down upon detection of any interruption in the regular flow of billets leaving the furnace chamber, the furnace It can operate at significantly higher temperatures than conventional enclosed skid furnaces. This provides a larger temperature difference between the furnace chamber and the billet, which increases the heat transfer rate and therefore the efficiency of the furnace. For example, in one form of a furnace according to the invention designed to heat positive billets, the skids are made of Inconel (Inconel).
l) Is 00 sheets, the furnace lining includes a layer of ceramic fiber date, and the furnace is made from sheets of
It is possible to operate at a temperature of 200'C, which is substantially higher than the positive melting point (FF o'c), creating a billet temperature of approximately ?50oC at the exit of the furnace chamber. Assuming that the time required for the detector to detect an interruption in the flow of billets from the furnace and shut down the burners is not too long, the temperature of the billets in the furnace will rise to the melting point. The temperature of /
From 200°C it will drop below Ir60qc.

the billet detector is reset by an air pressure sensor that generates a noggle in response to passage of the J-let down the feed chute forming at least a portion of the feed path, and each noggle from the sensor; A timer may be included that serves to shut down the burner if it is not reset by the signal within a predetermined period of time after the previous period.

The sensitivity of the detector is therefore determined by the setting of the timer. The timer may be a pneumatic device, the pneumatic device being an orifice bleed device.
a pressure switch arranged to generate an electrical output signal if the pressure in the tank has decreased to a predetermined low value;
It is returned to a predetermined high value in response to each noculus from the sensor.

Interruptions in the regular flow of billets down the feed chute are
due to one or more billets leaving the skid in the furnace chamber, due to a failure in the feed mechanism, or because billets are being fed to an automatic press and the press stroke is used to direct operation of the feed mechanism. It can be triggered by stopping the press when the press is stopped. However, whatever the reason for the interruption, it will be detected almost immediately and
Burner closes automatically. In addition, shutting down the feed mechanism preferably causes burner closure to be carried out automatically, so that it is not intended to prevent the feeding of any billets to the press immediately following an interruption, but rather primarily to ensure that the furnace is restarted again. When started, a reset mechanism is automatically activated to ensure that billets are automatically rejected until the furnace reaches its operating temperature and the billets leaving the furnace chamber are at the required temperature. . To this end, once the sekt mechanism has been activated, the reset mechanism remains activated until it is activated by the operator who determines when the billet is ready to be fed through the feed chute to the press. Arranged in

The reset mechanism may be located upstream or downstream of the billet detector in the feed path, but is preferably located upstream and includes a reset chute and a gate so that the dart is located in the feed chute as the billet leaves the furnace chamber. reset instead
between an open position arranged to fall down the chute (reset mechanism is actuated) and a closed position arranged to fall down the feed chute through the billet leaving the furnace chamber; can be moved, for example by a pneumatic cylinder.

The burner is preferably of the high speed premix type fitted to the top of the furnace chamber and supplied with the air/gas mixture by a standard air blast control train.

The gas/air mixture is ignited by an electric ignition probe inside the burner, combustion takes place inside the quart of the burner, and the hot combustion products are
From the fall it is discharged into the furnace chamber through a convergent slot just above and in line with the skid. The furnace can of course be equipped with more than one burner depending on the required length of the furnace chamber in relation to the size of the billet to be heated.

The burner control means are preferably low-light biased so that the burners always light at low heat and then proceed to high heat, and when the operating temperature of the furnace is reached, this is preferably triggered by a temperature sensor in the furnace chamber. The air supply to the burner in response plus) is maintained substantially constant by adjusting the air valves in the lanes. This can be a thermocouple mounted under the skid.

Preferably, the air and gas supply to the burner is equipped with a pressure sensor and arranged such that if either the air pressure or the gas pressure falls below a predetermined minimum value, the burner is deactivated. has been done. Therefore, not only will the burner not be able to start without sufficient gas and air pressure, but the burner will not be able to start if there is an appreciable drop in gas or air pressure during operation of the furnace, e.g. automatically closed by closing the valve controlling the source.

Preferably, the furnace chamber includes two zones. That is, it includes a lower region in which the skid is mounted and an upper region in which the burner is mounted, the upper region being hinged to the lower region so that it can be moved up and down, for example by a pneumatic cylinder, for opening and closing the furnace chamber. ing. With this arrangement, the furnace of the present invention combines the ease of access of an open hearth furnace with the higher efficiency of an enclosed skid furnace. As a safety precaution, the furnace is preferably equipped with an inch that opens to deactivate the burner if the furnace chamber is not closed.

Particular embodiments of the furnace according to the invention will be described below with reference to the accompanying drawings.

The furnace shown in the drawings produces approximately 7 ml of small plus billets for feeding into automatic punching niblets (not shown).
It is designed to heat to s ooc temperatures.

The furnace consists of a steel casing split into λ parts, a folded channel section 3 and an end plate 4 welded to this section 3.
, 5, and an upper or lid portion 2 comprising a folded and inverted channel section to which end plates 7 and 8 are welded.

The lower casing part 1 is fixed as a whole on a suitable support designated at 9, the upper part 2 being hinged to the lower part 1 by a hinge pin 10, with a hinge pin 1o extending along one side of the casing and It is pivoted in 7 laterally extending runs of the end plate 4°5.7.8. The casing is 1:1
Arranged to be opened and closed by moving the lid 2 up and down around the hinge pin 10 by a pneumatic cylinder IIK,
The pneumatic cylinder 11 has its lower end pivoted on a column 12 fixed to the casing lower part 1 and has a length of 45 mm.
It has a piston rod 13 to which a lever 14 fixed to the lid 2 is pivotally connected approximately in the middle. A hook-shaped catch, 15, with an adjustment handle 16 is pivotally connected to the lever 14, so that when the lid is opened it is held fixed between a pair of anchor grates 190 fixed to the sides of the base l. It can be locked in the open position by engaging the hook end of the catch under pin 18. One of the anchor plates 19 is fitted with a microswitch 20 that detects when the lid 2 is opened, and this microswitch 20 is closed only when the casing is fully closed. Anchor plate 1
Both 9 and the lever 14 are provided with bearing holes through which the hinged bin 10 passes, which bearing holes provide additional support for the hinged bin sump.

As shown in Figure 9, the lower part 1 and upper part 2 of the furnace casing
is lined with a heat-resistant ceramic fiber material 21, and the lid 2 is lined with a heat-resistant ceramic fiber material 21.
When the casing is closed, a longitudinally extending furnace chamber of relatively small rectangular cross section is formed substantially in the middle of the casing by a channel in the lining of the casing lower part l. Lower part 1 ceramic fiber liner/
21 covers the sides and bottom left end wall of the channel section 3 as shown in FIG. 4 / forms a strong high temperature resistant lining for the furnace chamber 22 with a layer 23 of 160°C grade ceramic fibers. A layer 24 of wet felt of 400 cc grade ceramic fibers is included to line the inner and upper surfaces of layer 23. The ceramic fiber lining 21' in the upper part 2 comprises a layer 25 of a 1260't' grade ceramic fiber blanket, a layer 26 of a 260°C grade ceramic fiber date, and a layer 26 of a 1600°C grade ceramic fiber blanket. the outermost (i.e. facing the furnace chamber 22) layer 27 of felt, which are cut and inserted into a pair of screws fitted into the lid part 2 towards one end of the casing. Around the burner unit 28,
It is fitted around the furnace tube opening at the opposite end of the casing. The wet felt layers 24 and 27 of ceramic fibers are applied wet and dried in place before operation of the furnace. When the casing is closed, the furnace chamber 22 is sealed by a blanket 30 of ceramic fibers fitted into the lower part 2. A V-shaped skid 31 extending longitudinally through the furnace chamber is centrally installed into the base of the furnace chamber 22 and extends through an inlet opening 32 at one end and an outlet opening 33 at the other end of the casing lower part 1. The skid 31 is made of Inconel, a lightweight heat-resistant material.
) is folded back at 90 degrees from a strip of 600 and fixed at the outlet end of the casing lower part l, so as to be free to expand at the inlet end where an overlapping inlet section 34 is provided to accommodate the movement of the skid 31.

The burner 28, mounted within the lid 2 of the furnace casing, has a standard air supply conduit 35 which branches to supply a pair of injectors 36 carrying gas supplied to each from a gas supply conduit 37. It is of the high speed premix type, with the air/gas mixture supplied by an air blast control train. The air supply conduit 35 is connected to a low pressure sensor (not shown).
and a regulating valve to control the air supply (as described below).
(not shown). The gas supply conduit 37 also houses a low pressure sensor (not shown) and is equipped with a control valve (not shown) for cutting off the gas supply for burner closure.

The gas/air mixture is led from the injector 36 to the burner 28 by a tube 38. /? - each of the casings 28 includes a refractory-lined upper section 39 mounted on top of the upper part 2 of the casing and carrying a series of gas/air mixing tubes 40 and a spark ignition globe 41; a lower section 42 that fits inside the stretched lid 2 and includes a fall cast from fused alumina refractory material. The gas and air supplied to each parser 28 is directed downwardly through a mixing tube 40 for combustion within the fall of the lower section 42, with the hot combustion products immediately above and in line with the skid 31. Eggplant 1111 Furnace chamber 2 through the slot outlet 43 converging from the fall
Enter 2. As mentioned earlier, the burner 28 is located in the furnace chamber 22.
．． The hot combustion products entering the furnace M22 move along the furnace chamber toward the outlet end, where they enter the furnace through the furnace opening 29. They are arranged so that they come out of the room.

During operation of this embodiment, burner 28 brings furnace chamber 22 to an operating temperature of approximately 200 c'c within 2 minutes;
This temperature is measured by a thermocouple (not shown) placed under the skid 31. When the operating temperature is reached, this temperature is controlled by a control device (not shown) for controlling the supply of air/gas to the burner by actuating a regulating valve in the air supply conduit 35 in response to a thermocouple. is maintained substantially constant.

The part of the air/gas supply train to the burner 28 shown is fixed to the lid 2 of the furnace casing by means of a screw 44.45 and a crank 7'4.6, so that the lid 2 can be opened and closed. It should be noted that the movement of the train when moving is accomplished by flexible parts within the air and gas supply conduits 35 and 37'.

A billet feed mechanism 47 for directing and directing a regular feed of billets onto the inlet section 34 of the skid 31;
Adjacent to the inlet end of the furnace casing. In this embodiment, the billet supply mechanism 47 includes a pair of vibrating dewls (
(not shown), the oriented billet is passed from the vibrating dewl via a lateral feed path to the skid 3
a pair of feed positions on opposite sides of stopper 49 aligned with one axis. A pair of pushers 50 arranged to be moved forward and backward by a pneumatic cylinder 51 are associated with one supply position, and are moved from one supply position through a guide 52 with a chi and two by actuating the cylinder from the companion billet. They are alternately pushed into the outlet paths 53 leading onto the inlet section 34 of the skid. During operation, the cylinders 51 of the feed mechanism 47 are activated in response to signals from the press being sent by the furnace, so that one of the punchers 50 is advanced each time a billet is punched by the press. pushing the new billet towards the skid, thereby advancing all billets on the skid;
a guiding channel 55 arranged to receive the billet from the exit end of the skid 31 and arranged for the billet to fall therethrough so that the leading billet is fed into the press for the next punching stroke; A billet discharge mechanism 54 is mounted on the support 9 adjacent the outlet end of the furnace casing, leading to a vertical passage 56 which forms the introduction of a feed chute 57 leading to the press. For the purpose of detecting interruptions in the regular supply of billets to the press during normal operation, the press is equipped with a billet sensor 58 in the form of a lever pivoted about an axis 59; It has a rest position determined by a stop horn 60 that engages the lever, with one arm 61 of the lever projecting laterally into the passage 56 and the other arm 62 of the lever 62''i 9 atm pressure 0 passage &,&j,gu,・1''' falls down the passage 56 into the feed chute 5'7, the billet engages the arm 61 of the sensor 58, causing the sensor to swing about its axis; Arm 62 does not block passageway 63 so that pulses of air can flow to a timer (not shown) until passageway 63 is closed again when sensor 58 returns to its rest position. sets the ties in operation, and if a predetermined period of time elapses without any other billet falling down the aisle 56, the ties are arranged to expire and issue a closing signal. This predetermined time is set to be greater than the normal time interval between successive billets in regular feeding to the press.

Therefore, during normal operation, the timer does not expire when the next billet falls down the aisle 56, causing the sensor 58 to pivot and a new billet to be sent to the timer. , where it is immediately restarted. However, if for any reason there is an interruption in the regular flow of billets down aisle 56, the timer will expire one hour and initiate a stop signal. In response to this stop signal, a control valve (not shown) in gas supply conduit 37 is closed to close the burner.

A reject device is also incorporated within the billet discharge mechanism 54. It includes a slide 64 forming part of the floor of the channel 55, which slide 64 opens a second vertical passage 65 in the path between the passage 56 leading to the feed chute 57 and the discharge end of the skid 31. Can be moved sideways to expose. A third vertical passageway 65 leads to a resect chute 66 and prevents any beer from reaching the supply passageway 56 and the scene 57 when opened.

The slide 64 is moved between its open and closed positions by a pneumatic cylinder 67, which
It has a piston rod 68 mounted on the side of the casing lower part 1 and connected to the slide 64 via a series of pivoted links 69, 70, 71. The cylinder 67 is arranged to be actuated to open the slide 64 at the same time as the burner is closed, and the resect cylinder 67
Means (not shown) are also provided for manually activating the . In either case, however, at start-up or after any stoppage, until the operator decides to close the slide 64, i.e., until the operator is satisfied that the billet has been heated to the required temperature. The slide can only be closed by manual operation of a switch (not shown) so that billets are not fed from the furnace to the press.

During operation, detection of the absence of billet flow by sensor 58, low pressure in any of the air and gas supply conduits 35 and 37, as detected by suitable low pressure sensors, as detected by switch 20. The furnace controller is arranged such that the gas control valve closes and shuts off the burner in response to any one of the following events: opening of the furnace chamber lid 2 and operation of the stop button by an operator. has been done. In addition to closing the gas control valve, the occurrence of any seven of the above events will cause the controller to drive the regulated air valve to its minimum setting, reactivating the billet feed mechanism 47 and dispensing billet. Stop and resect gate 64 Chute 66
Activate the retract mechanism to open. If the lid switch 20 is open, or if any of the low pressure sensors in the air and gas supply conduits signal that the pressure in the conduits is too low, the burners are ignited. It should be noted that this is not possible.

[Brief explanation of the drawing]

Figure 1 is a side view of the furnace, Figure 2 is a plan view of the furnace, Figure 3 is an end view of the furnace, and Figure 1 is a cross-sectional view through the furnace casing taken along line ■-■ in Figure 1. It is. 21... Lining 22... Furnace chamber 11... Pneumatic cylinder 13...
... Piston rod 28 ... Gas burner 31 ... Skid 47 ... Billet supply mechanism 56 ...
...... Supply path 57 ...... Supply chute 58 ...
...Air pressure sensor 50... Gutsusha 51... Cylinder 61.62... Arm 67...
... Reject cylinder 68 ... Mon. Piston rod 64 ... Dirt 66 ... Reject chute jl. Procedural amendment (formality) 58. ．． 2.24 Showa year
Month 1 (Mr. 1, Commissioner of the Patent Office, Incident Indication: 1939 Patent Application No. 1/G301 No. 2)
, Title of the invention Billet heating furnace 3, Relationship with the case of the person making the amendment Applicant name Britei Sonyu Gas Corporation 4, Agent 5, Date of amendment order Showa! ;I! i′ year/month 2j day 6, all drawings subject to amendment

Claims (1)

Claims: 11) In an enclosed skid type furnace for heating a billet to a predetermined temperature below its melting point as the billet is moved along the skid at a predetermined rate through a furnace chamber, said furnace A billet feed mechanism is provided adjacent to the inlet end of the furnace chamber to regularly feed billets onto and along the skid, and a billet feed mechanism is provided adjacent to the inlet end of the furnace chamber to raise the temperature in the furnace chamber to an operating temperature above the melting point of the billets. a gas burner, a burner control means for maintaining a substantially constant operating temperature, a feed path adjacent the outlet end of the furnace chamber for receiving billets as they leave the furnace chamber; a billet detector arranged to detect an interruption in the regular flow of billets and to stop the burner when this interruption is detected and actuate and feed the burner if the burner is stopped; a retract mechanism for deflecting the billet from the path; the thermal mass of the skid and the refractory lining of the furnace chamber are such that after the burner is shut down, the temperature of any billet stagnant in the furnace chamber reaches the melting point; A furnace characterized in that the temperature in the furnace chamber is such that it falls below the melting point of the billet before it can rise. 8. The furnace of claim 7, wherein: (2) the heat-resistant lining of the furnace chamber includes a ceramic fiber material. (3) The skid has a ■-shaped cross section, and the skid has an Inconel (I
Furnace according to claim 1 or 2, characterized in that it is made from Nconel A 00. (4) The skid is fixed at the outlet end of the furnace chamber and is free to expand at the entrance chamber of the furnace chamber. furnace. (5) The feed path includes a chute, and the billet detector is reset by an air pressure sensor that generates a constant pulse in response to the billet passing down the feed chute and each pulse from the air pressure sensor. , What if A within a predetermined time after the previous Noculus? 2. A furnace according to claim 1, further comprising a timer operative to stop the burner if not reset by the pulse. 16) the sensor includes a pivoting member having one arm projecting into the feed chute and the other arm blocking the germ-generating air jet and having a rest position;
The arrangement is such that the passage of billets down the feed chute projects into the chute so that the member is rocked to allow the passage of the billet and the movement of this member generates a pulse so as not to obstruct the air jet. Claim 3, characterized in that the arrangement is such that it engages with the arm.
The furnace described in Section. (k) The timer is a pneumatic device, said pneumatic device being arranged to generate an electrical output signal if the pressure in the tank drops to a predetermined low value. and a pressure switch in which the pressure in the tank is returned to a predetermined high value in response to each pulse from the sensor. Furnace according to item 6. (8) The furnace according to any one of claims 1 to 7, wherein the reset mechanism is located upstream from the billet detector in the supply path. (9) The reset mechanism includes a reset chute and a gate, the dart is arranged in an open position such that the leaving billet in the furnace chamber falls down the reset chute instead of the feed chute, and is movable between a closed position arranged to fall through a reset chute and down a supply chute;
The furnace according to any one of claims 5 to 7, characterized in that: 1. ...:1, QO) The reset mechanism is arranged so that, when activated, it remains in an activated state until it is reset by an operator.
Furnace according to any one of paragraph 9. (lυ) The burners are connected to a high-velocity reserve fitted within the top of the furnace chamber such that the hot combustion products exiting the burner are discharged into the furnace chamber through converging slots directly above and in line with the skid. 71. Furnace according to any one of claims 1 to 70, characterized in that it is of the mixed type. (+3) A mixture of air and gas is supplied to the burner by an air-plast control train, 2. A furnace as claimed in claim 1, wherein the burner control means includes means for adjusting an air valve in the airplast train in response to a temperature sensor in the furnace chamber. ++31 characterized in that the device for supplying air and gas to the burner is equipped with a pressure sensor, and the burner is arranged in such a way that it becomes inoperable if the air or gas pressure falls below a predetermined minimum value. The furnace according to claim 1 or 72. (14) The furnace chamber includes a lower area in which the skid is placed and an upper area in which the burner is installed, and the upper area is The furnace according to any one of claims 1 to 13, characterized in that the furnace is hinged to the lower section so that it can be moved up and down to open and close the furnace chamber. The furnace according to claim 1, characterized in that the furnace is equipped with a switch that opens to deactivate the burner if the furnace chamber is not closed. Furnace according to any one of claims 1 to 1S, characterized in that the billet feed mechanism is arranged to stop if the burner is stopped. A patent characterized in that the path is arranged to feed billets to a punching press, and the billet feeding mechanism is arranged to feed billets onto a skid in synchronization with the stroke of the press. A furnace according to any one of claims 1 to 16. A furnace according to claim 1, substantially as hereinafter described with reference to the accompanying drawings.