JPH02309182A - Continuously heating furnace - Google Patents

Abstract

PURPOSE: To supply just a required volume of protective gas to a furnace by detecting the height of a work being set in the furnace, adjusting the height at the opening of a door depending on the detected height and then regulating the volume of protective gas being supplied correspondingly. CONSTITUTION: Means 32 for detecting the height of works 60, 61 is connected with a process computer 38 and a detected height is converted through the computer 38 into a signal for controlling a door opening height adjusting means. It is also converted into a signal for controlling a gas quantity regulator 54. A door is brought to an optimal height and, at the same time, the detected height is converted through a central calculation unit into a position control signal for controlling the gas quantity regulator 54 to supply a correct quantity of protective gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for heat treating workpieces under a continuously supplied protective gas flowing out along the workpiece-inlet opening and the workpiece-Aradred opening of the furnace. A continuous heating furnace, which is equipped with a transport device for transporting the workpiece through the furnace and a movable door attached to the workpiece-inlet opening or the workpiece-Aradred opening. related to things.

In continuous heating furnaces of this type, which are known from the prior art, for example from German Patent No. 2,601,658, the workpieces undergo a heat treatment while passing through the furnace.

Typical heat treatments include high temperature brazing with hard solder, brazing with aluminum solder, melting, cauterizing, hardening, tempering, molding or similar treatments. The purpose of the protective gas that is continuously supplied to the furnace is to prevent oxidation processes of the workpieces, which are usually made of metal, from occurring during the heat treatment. Protective gases of this type, which are supplied to the furnace and then exit along the workpiece-inlet opening or the workpiece-Aradred opening, often explode together with the oxygen contained in the air (air oxygen). Gases such as:

A flame tunnel is thus formed in the area of the workpiece inlet opening and the workpiece Already opening.

The problem with the flow of protective gas from the inner chamber of the furnace towards the workpiece-inlet opening or the workpiece-Aradred opening located on the opposite side is to prevent atmospheric oxygen from entering the furnace completely or at least completely. It's mostly about preventing it. A slidable door mounted in front of the workpiece-inlet or workpiece-alladred openings allows these openings to be opened and closed over a more or less extensive range. 'The amount of protective gas supply to the furnace required to ensure that atmospheric oxygen is preferably prevented from entering through these openings is a function of the size at these openings. The relationship between the amount of protective gas supplied and the opening size is a quadratic function, so if the height of the door is doubled, the amount of protective gas supplied to the furnace will be more than doubled. Must be set to .

The disadvantage of the type of continuous heating furnace mentioned at the beginning is that it is necessary to prevent air oxygen from entering the furnace even when the door is opened as much as possible, and to continuously supply a large amount of protective gas to meet this condition. The problem is that it is not always possible to guarantee that supplies will be provided. If the door were not opened in this case, more protective gas would be supplied to the furnace than would otherwise be required. In most cases, hydrogen is used as the protective gas, but since this type of gas is very expensive, it is uneconomical and undesirable to supply the protective gas in excess. Moreover, if hydrogen is used as a protective gas, the deflagration generates a large amount of heat, which must be dissipated outside the furnace. This heat release, which most often takes place through chimneys or flues,
It must be said that this is a waste of energy and therefore uneconomical.

It is already known to provide this type of continuous heating furnace with a manually adjustable gas volume regulator, but in this case, the desired gas volume adjustment cannot be achieved unless the operator manually operates it. . Moreover, in known continuous heating furnaces of this kind, it is certainly possible to manually adjust the height of the door opening, which in most cases is done by completely opening the door during operation. It is done in this format. However, when relatively short workpieces are introduced into the furnace, such a high opening as can be obtained by fully opening the door is not required at all.

Problems to be Solved by the Invention Therefore, the object of the present invention is to eliminate the drawbacks of the conventional continuous heating furnace of the type mentioned at the beginning (improvements thereof and to improve the size of the workpiece to be processed). The aim is to make it possible to operate under optimal conditions depending on the situation, that is to say with just the required amount of protective gas.

Means for solving the problem To solve the above problems (according to the proposed measures of the invention, means for detecting the height value of the workpiece to be charged into the furnace and means for adjusting the height of the door opening in accordance with the height value of the workpiece, and a gas volume regulator for adjusting the amount of protective gas supplied to the furnace in accordance with the height of the door opening. and is provided.

Operation and Effect of the Invention By detecting the height value of the workpiece to be charged, the door can adjust the opening height to be sufficient to charge the workpiece into or out of the furnace. All you have to do is open it up so that you can get it. In addition, by controlling the gas amount regulator according to the height of the door opening, we can obtain the optimal furnace conditions at the opening height detected at the front edge. In order to reliably avoid the ingress of atmospheric oxygen into the furnace, it is achieved that the furnace is supplied with only the amount of protective gas that is ultimately required.

In this way, it is ensured that protective gas is supplied to the furnace in the respective required amount, and thus economical operation is carried out, so that the above-mentioned object of the invention is completely solved.

Embodiment According to a particularly advantageous embodiment of the invention, the means for detecting the height of the workpiece are connected to a process computer, and the detected height value is determined by the process computer to determine the opening of the door. At the same time, the control signal is converted into a control signal for controlling the means for adjusting the height of the section, and at the same time, it is also converted into a control signal for controlling the gas amount regulator.

This structurally simple measure allows the door to be brought to the optimum height position and, at the same time, to control the position of the gas flow regulator in such a way that the correct amount of protective gas is supplied. The advantage is that the values are converted into appropriate control signals via a central calculation unit.

In a further advantageous embodiment according to the invention, the means for detecting the height of the workpiece have a phototube device arranged on the side of the transport device, the phototube device passing by. The height of the workpiece to be transported is detected and the measurement signal is transmitted as an electrical pulse to the process computer.

The advantage obtained with this measure is that the workpiece is not brought into contact with mechanical measuring devices, since the optimum height value at the workpiece is detected, and therefore, for example, Since it is possible to change the position of the paste, even when the solder paste melts, it is avoided that it flows into the respective solder joint. A phototube arrangement, which is constructed, for example, as a diode grid, is a component of robust and simple construction. In addition, this measure provides
The advantage of this method is that the detected height value is converted into electrical pulses, which are fed directly to the process computer without any further conversion measures and processed there accordingly. can do.

In a further advantageous embodiment according to the invention, if the height of the supplied workpiece is changed, until the workpiece with the previous height passes through the outlet door,
The control device of this outlet door is maintained in the previously adjusted height position by the process computer.

The advantage of this measure is that if the height of the workpiece is changed,
While the inlet door is already adapted to the new conditions, the outlet door remains in its original position until the workpiece according to the previous specification, which has already been received in the furnace, passes through the furnace. For example, when the workpiece height is changed from a low value to a high value, the outlet door remains in its low height position until the last short workpiece leaves the furnace. This type of operating method is used when the flow characteristics of the protective gas in the furnace are not influenced by the different heights of the inlet and outlet doors.

In a further advantageous embodiment of the invention, the means for adjusting the opening height have a servomotor which can be controlled by a process computer, which servomotor adjusts the door to the correct position via a linkage. It is configured to be moved to a certain opening height.

The advantage of this measure is that it provides a robust and simple means of ensuring proper movement of the door. In addition, in order to equip a ready-made furnace with this simple means,
It is also possible to incorporate it later.

In a further advantageous embodiment of the invention, the process computer stores a function which determines the supply of protective gas from the door opening height as a function of the respective furnace characteristics; The gas volume regulator is configured to control the gas volume regulator.

The advantage of this measure is that the furnace designer can check the particular furnace characteristics at the manufacturer's end, i.e., what is required for an optimal protective gas function at a given door height. It is possible to detect the amount of protective gas in advance. Since the gas amount regulator is controlled according to this function, each furnace can be operated under the most economical conditions. It goes without saying that each of the above-mentioned features and each of the features described below can be applied not only in the combinations described in each case but also in other combinations or individually, without departing from the scope of the present invention. Don't bother.

The invention will now be described in detail with reference to the embodiments shown in the accompanying drawings: A continuous heating or protective gas furnace 10 is shown in FIG.
It has an endless conveyor belt 12, as shown by arrow 13 in FIG.
performs a transport movement in one direction. This endless conveyor belt 12 is driven by an adjustable drive, not shown, which provides it with a predetermined circulation (rotational) speed. Typical belt transport speed is 100 m per minute
The value is set within the range of m to 400 mm.

The protective gas furnace 10 also has a housing 14 in which the conveyor belt 12 runs.

In this case, a cooling zone 18 is connected to the rear of the heating zone 16 in the direction of passage of the conveyor belt 12 .

A workpiece inlet opening 21 is provided in the casing 14, and this workpiece inlet opening can be opened and closed by a movable inlet door 20. At its opposite end, the casing 14 is provided with a workpiece-to-alladred opening 23 which can be opened and closed by an outlet door 22 configured in the same way as the inlet door 20.

Inlet door 2 seen in the conveying direction of the conveyor belt 12
0, a combustion chamber 24 having a chimney 26 at its upper end is located.

Similarly, a combustion chamber 28 is connected immediately behind the outlet door 22, and a chimney 30 is also provided at the upper end of the combustion chamber 28.

In front of the combustion chamber 24, seen in the direction of movement of the conveyor belt 12, there is a workpiece 60 which is conveyed by the conveyor belt 12 in the direction of the arrow 13 through the protective gas furnace 10.
Means 32 are arranged for detecting a height of ~62.

The means 32 for detecting the height of the workpieces 60-62 include:
A diode grid 3 arranged on the side of the conveyor belt 12
It has a photocell configured as 4. When a workpiece 60 is passed past this diode grid 34 by the conveyor belt 12 as shown in FIG. A predetermined electrical signal is generated to be supplied to the process computer 38, and the height of the workpiece is detected thereby.

The process computer 38 is connected via a lead 40 to a servo motor 42 which is coupled to the inlet door 20 via a link rod 44.

In the case of the embodiment shown in FIG.
4 is recording the height position "3", therefore, the process computer 38 indicates that the connecting rod 44 is in a state where the servo motor 4 is
The servo motor 42 is controlled so that the height is adjusted to the arrow tension position "3" by the arrow 2. In this case, the inlet door 20 has been raised such that the workpiece 62 at height position "3" passes just under the raised inlet door 20.

The process computer 38 is further connected via a conductor 46 to another servo motor 48, which is itself coupled to the outlet door 22 via a connecting rod 50.

Servo motor 48 is constructed in the same manner as servo motor 42 described above and occupies height position "3". In this case, the outlet door 22 is also raised until the workpiece 62 can just pass under it and be removed from the protective gas furnace 10 .

The process calculator 38 is further connected via a conductor 52 to a gas quantity regulator 54.

This gas quantity regulator 54 is connected to the protective gas which comes from the gas supply line 56 as indicated by the arrow 57 and is supplied to the heating zone 16 of the casing 14 via the gas quantity regulator 54 and the gas supply line 59. It is used to adjust the amount of 58.

The protective gas 58 supplied to the heating zone 16 splits into two partial streams, one of which is directed in the direction of the workpiece-inlet opening 21 and passes under the opened inlet door 20. It flows out from the casing 14 and enters the combustion chamber 2.
4. Within this combustion chamber 24, a protective gas 58, ie hydrogen, forms a flame chamber with air/oxygen, as indicated by flame 25 in FIG.

The other partial flow in the protective gas 58 flows through the casing 14
through the cooling zone 18 of the workpiece-outlet opening 2
3 and flows out of the casing 14 under the open outlet door 22 and into the combustion chamber 28. Also in this combustion chamber 28, hydrogen gas is combusted to form a flame chamber 29.

In this case, the gas amount regulator 24 is set according to the standard at the height position "3", and the protective gas 58 is supplied to the casing 14 in an amount necessary to prevent air oxygen from entering the casing 14. Make adjustments to supply the

Figure 2 shows the amount of protective gas supplied per hour (SG
) in cubic meters and door height HT
') is shown in a graph plotting the relationship between the values measured in millimeters.

The functions shown in FIG. 2 characterize a given type of furnace, taking into account the pass-through width and pass-through height within the furnace. Since the relationship between the protective gas amount (SG) and the door height (HT) shown in FIG. can be adjusted according to the characteristics defined in FIG.

In order to be able to clearly illustrate the invention, FIG. 1 omits the heating device and the transfer device, which must naturally be arranged in the furnace.

If the height of the workpiece guided past the diode grid 34 is varied, this is communicated to and stored in the process computer 38;
This process computer 38 then controls the servo motors 52 to 58 and the gas amount regulator 54 according to the information.

If the length of the newly loaded workpiece is higher than the height of the workpiece 60 shown in FIG. 1, the inlet door 20 is raised according to its dimensions. In such a case,
By appropriately preprogramming the process computer 38, the outlet door 22 can also be raised at the same time, but in most cases this will be desirable. This is because if the inlet door 20 and outlet door 22 are lifted at the same time, significant changes in the flow characteristics within the furnace can be avoided.

In this case, the outlet door 22 is kept at the height position "3" until the workpiece 60 also passes through,
It is also possible that it can only be lifted afterwards.

In the opposite case, that is, when workpiece 60 is followed by workpieces shorter than this workpiece, it is natural that the last taller workpiece, workpiece 60, will leave the furnace. until the outlet door 22 is at height position "3".
The outlet door 22 must be controlled so that it remains at . The outlet door 22 is then lowered to accommodate the lower height of the following workpiece. In such cases, too, depending on how the flow conditions in the protective gas furnace are affected by the unevenly tall inlet doors 20 and outlet doors 22, the short initial workpieces may be exposed to the diode grid 34. It is possible to lower the inlet door 20 simultaneously with the passage, and it is also possible to lower the inlet door 20 only after the last tall workpiece has passed the outlet door 22.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal section through a continuous heating furnace according to the invention, and FIG. 2 is a graph in which the amount of protective gas supplied is plotted in relation to the door height value. 10... Continuous heating furnace or protective gas furnace 12...
... Conveyor belt 13 ... Arrow 14 indicating the direction of conveyance of the workpiece by the belt ... Furnace casing 16 ... Heating zone 18 ... Cooling zone 20... Inlet door 21... Workpiece-inlet opening 22...
... Outlet door 23 ... Workpiece - Aradred opening 24 ...
... Combustion chamber 25 ... Flame 26 ... Chimney 28 ... Combustion chamber 29 ... Flame chamber 30 ... Chimney 32... Means 3 for detecting the height of the workpiece
4...Diode grid 36...Conducting wire 38...Process computer 40...Conducting wire 42...Servo motor 44... - Connecting rod 46... Conductor 48... Servo motor 50... Connecting rod 52... Conducting wire 54... Gas amount regulator 56. ... Gas supply pipe line 57 ... Arrow 58 indicating the direction of supply of protective gas.
...Protective gas 59...Gas supply pipe lines 60-62...Workpiece

Claims (1)

[Claims] 1. Workpiece-inlet opening (21) and workpiece-outlet opening (23) of the furnace (10) that are continuously fed.
The workpiece (
60) to (62), which is a continuous heating furnace for heat treating the workpieces (60) to (62), and includes a conveying device (12) for conveying the workpieces (60) to (62) to pass through the furnace (10), and the workpieces. Inlet opening (21) to workpiece-outlet opening (
23) with movable doors (20) to (22) attached to the furnace, the height value of the workpieces (60) to (62) to be charged into the furnace (10); means (32) for detecting a detected workpiece (60);
means (42), (44), (48), (50) for adjusting the door opening height according to the height value of ~(62);
and a gas amount regulator (54) for adjusting the amount of protective gas (SG) supplied to the furnace (10) according to the door opening height (HT). Continuous heating furnace. 2. Means (32) for detecting the heights of the workpieces (60) to (62) are connected to a process calculator (38), and the detected height values are sent to the process calculator (38).
) for adjusting the opening height of the door (4).
2), (44), (48), and (50), and is also converted into a control signal that controls the gas amount regulator (54) at the same time. The continuous heating furnace according to claim 1, characterized in that: 3. The means (32) for detecting the heights of the workpieces (60) to (62) have a phototube device (34) arranged on the side of the conveying device (12), and the phototube device is configured to detect the height of the conveyed workpieces (60) to (62) passing by and transmit the measurement signal as an electrical pulse to the process computer (38). The continuous heating furnace according to claim 2. 4. When the heights of the supplied workpieces (60) to (62) are changed, the workpieces (6
0), (62) passes through the outlet door (22).
), (50) are configured to be maintained at the previously adjusted height positions by the process calculator (38). 5. means for adjusting the height of the door opening (42);
(44), (48), and (50) are process computers (3
Servo motors (42), (48) controllable by
), and this servo motor drives the connecting rod (44), (
5. According to any one of claims 2 to 4, the door (20), (22) is configured to be moved to a proper opening height (HT) via the door (59). continuous heating furnace. 6. The process computer (38) stores a function that affects the supply amount of protective gas depending on the door opening height (HT) according to the furnace characteristics in each case, and adjusts the gas amount according to this function. Continuous heating furnace according to any one of claims 2 to 5, characterized in that it is configured to control a furnace (54).