JPS6033899A - Operating method of conveyor in drying furnace - Google Patents

Abstract

PURPOSE:To produce inexpensively and efficiently a welding rod by starting and stopping the operation of transfer conveyors on judging the presence or a absence of the welding rod by a detecting means provided at the end on the receiving side of the conveyor and restarting automatically the operation when the stop time exceeds the permissible stangnating and drying time intrinsic to a drying furnace. CONSTITUTION:A painted arc welding rod (a) carried by a production line from a painting and extruding machine via a transfer conveyor 1 is received by a flight conveyor 2 and is conveyed in a drying furnace H. A means 10 for detecting the rod (a) is disposed near the end on the receiving side of the conveyor 1 and the presence or absence of the rod (a) is detected by the means 10 and is outputted to a control command part 11. The part 11 strats and stops the operation of the conveyors 2, 3, 5 in the furnace in accordance with said output. On the other hand, the part 11 restarts the operation of the conveyors 2, 3, 5 in the furnace when the stop time during stopping of the conveyors exceeds the permissible stagnating and drying time intrinsic to the furnace H.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the drying process in the manufacturing process of coated arc welding rods, and more specifically, by appropriately controlling the drive of a conveyor that conveys the inside of a drying furnace, it is possible to improve the drying process of the coated arc welding rod. The present invention relates to a method of operating a conveyor in a drying oven that enables a high packing density.

Generally, a coated arc welding rod is coated with 7 lux on the outer periphery of the core wire using a coating extruder, and then transported to a drying oven, where it is sufficiently surface-dried and then taken out as a product. Once the series of production lines in Part B are started, they will be operated continuously with productivity in mind.

That is, the conveyor (hereinafter referred to as the "in-furnace conveyor") that receives the coated arc welding rods conveyed from the paint extruder via the transfer conveyor in an assembly line manner and transports them through the drying oven is naturally operated continuously.

However, when a so-called plunger type extruder is employed as a coating extruder, various problems arise due to the characteristics of the extrusion form as summarized below. That is, ■In a plunger-type coating extruder, the time required to insert the flux cake passes between the plunger operation and the next plunger operation. A considerable distance is left between the arc rod group and the same arc rod group that is successively pushed out by the next plunger operation. This kind of placement condition is also reproduced on the conveyor inside the oven, so when considering the thermal efficiency of the drying oven, the rate of heat loss is relatively large and the fuel consumption efficiency is bad. .

However, there is still a problem: (1) If the drying oven is of a so-called band type, conveyor troubles often occur, and as a result, the drying oven is likely to stop operating, resulting in the production line being stopped in the worst case scenario. In other words, in a band-type drying oven, the conveyor inside the oven is arranged in multiple stages (generally 3 to 7 stages in most cases) in the vertical direction, and the upper and lower 2 stages form a set and make one reciprocation. In order to reliably and smoothly transport the coated arc rods by the in-furnace conveyor, it is necessary to ensure that the coated arc rods are at least aligned and conveyed on the upper stage conveyor, and aligned and conveyed at the direction change section from the upper stage to the lower stage. It must be. In consideration of this point, conventionally, as shown in Figure 1 (schematic diagram of main parts of the conveyor in the drying oven), the A magnet 4 is arranged, and the painted arc rod a on the upper conveyor 3, which has been transferred from the transfer conveyor 1 via the attached conveyor 2, is magnetized by the magnet 4 on the conveyor 3. This is used to align the rods by repelling them. However, as mentioned above, since the painted arc rods a are transferred in groups at predetermined intervals, the painted arc rods a at both ends (the first and the last) of the group of painted arc welding rods A on the upper conveyor 3 ' tends to be oriented diagonally. If the welding rod a', which is still oriented diagonally, is guided by the guide conveyor 5 and enters the direction change section 6, the arc rod a' may be left leaning in the direction change section 6. .

If a subsequent arc rod A enters in this state, a so-called rod tangle will occur within the direction change section 6, and as a result, the in-furnace conveyor will have to be stopped. Also, depending on the vibration state of the upper conveyor 3, the above-mentioned degree of oblique orientation may be further increased, and the rod may fall from the upper conveyor 3 before reaching the guide conveyor 5, causing rod entanglement with the arc rod on the lower conveyor 8. Sometimes it happened. In any case, once such trouble occurs with the in-furnace conveyor, production efficiency will be greatly reduced, which is undesirable.

These problems are a concern, and in production lines where a plunger-type paint extruder is used, or where production is likely to be intermittent even if a single-screw type is used, the above-mentioned fuel There has been a strong desire to develop technology that can improve production and productivity by improving consumption efficiency and preventing trouble. The present invention has been completed through intensive research and attempts to provide a drying oven management technology, more specifically, a method of operating a conveyor in a drying oven, that can fully meet these demands. The operating method of the drying oven conveyor is as follows:
A means for detecting a painted arc welding rod is arranged near the receiving end of the in-furnace conveyor, and the detecting means determines the presence or absence of the welding rod to start and stop the operation of the in-furnace conveyor. The gist of this method is that when the time exceeds the permissible stagnation drying time unique to the drying oven, the operation of the oven conveyor is automatically restarted at that point.

The content of the present invention will be described in detail below, taking into account the progress that led to the adoption of such a configuration.

The inventors of the present invention first discovered that the conventional problem of poor fuel consumption efficiency and production efficiency is largely related to the condition in which articles are placed on the in-furnace conveyor. We focused on the fact that the cause was that the items were not placed on the conveyor, and the basic policy of technological development was to create a means to place items on the conveyor without gaps (hereinafter referred to as continuous placement).

This problem can be solved by adopting a control means that can maintain the discontinuity on the article receiving side in accordance with the discontinuity on the article supply side. However, in order to realize the adoption of such a control means, new problems must be solved. In other words, ensuring the above-mentioned intermittency is nothing more than temporarily putting the conveyor in the furnace on standby, so if the waiting time becomes too long, the painted arc rod on the conveyor will become over-dry and the quality of the products will deteriorate. This is because it does not necessarily lead to an improvement in productivity. Therefore, it is necessary to add a means for waiting as long as the quality does not deteriorate, or conversely, a means for canceling the standby immediately before the quality begins to deteriorate. Therefore, we investigated how to set the quality deterioration start time that should be an element of this standby release signal. In other words, the entire length of a drying oven installed in an automatic production line is generally divided into multiple zones with different temperatures, and a painted arc rod supplied at room temperature passes through each zone sequentially within a certain period of time (regardless of the moisture content).
In view of the fact that the design is based on the assumption that the drying time will pass within the same period (common to each zone), we felt that the fixed time common to each zone, that is, the allowable stagnation drying time unique to the drying oven, corresponds to the time when quality deterioration begins. Drying experiments of painted arc rods were carried out on a particular drying oven with zones. Table 1 shows the quality (proportion of defects) of dried arc rods and residence time in each zone. Decreased,
It means causing a defect in the welded part of the equipment to be welded,
Defects due to rod "cracks" mean that cracks occur due to the difference in dryness between rods or rods or rods and conveyor (especially the chain part) where they are in contact for a long time and where they are not. .

Figure 2 is a graphical representation of the experimental results in Table 1 to make it easier to understand. As is clear from this figure, if the stagnation time is shorter than about 60 minutes (a constant time common to each zone 1 to 5), the quality will be stable, but if it exceeds 60 minutes, the quality defect rate will increase. It was confirmed that the number suddenly started to increase.

Therefore, an additional configuration is adopted in which the above-mentioned quality deterioration start time, that is, the standby release signal element, is the stagnation drying allowable time specific to the drying oven, and when the allowable time is exceeded, the temporary standby of the conveyor in the oven is canceled and operation is restarted. At the same time, we succeeded in perfecting the basic structure of the means for connecting and placing it on the in-furnace conveyor.

When the intermittent operation continues without exceeding the standby time of the conveyor in the furnace, that is, the permissible stagnation drying time unique to the drying furnace, the state of the painted arc rod on the conveyor is as shown in FIG. Components in the figure that have the same configuration as the example in FIG. 1 are designated by the same reference numerals. Further, 10 is a detection means for detecting the presence or absence of the painted arc rod a, and 11 is a control command unit for controlling the drive of the in-furnace conveyor. Furthermore ■, ■.

... represents the order in which intermittent operation is continued. Therefore, from FIG. 3, it can be clearly seen that drying is carried out with the painted arc rods a being placed in series on the conveyor in the furnace. Therefore, there is no tangle of rods, and conveyor troubles can be completely prevented, and productivity can be improved by maintaining continuous operation. Further, since the rate of heat loss is relatively reduced due to the continuous mounting, fuel consumption efficiency is also improved.

On the other hand, if the allowable stagnation drying time unique to the drying oven is exceeded, the conveyor in the oven automatically restarts operation according to a command from the control command unit 11, and transfers the painted arc rod a from the zone to which it currently belongs to the next zone. As described above, the deterioration in quality is completely prevented, and this reflective effect can also improve productivity.

It should be noted that the above-mentioned embodiments are detailed explanations of the gist of the method of the present invention, and it is of course possible to implement the method by appropriately changing the design within the scope of the gist of the gist.

Since the present invention is structured as described above, even if a coated arc welding rod production line employs a plunger type coating extruder or a screw type extruder, production is likely to be interrupted. We succeeded in improving the fuel consumption efficiency of the line, especially the drying furnace, and preventing the occurrence of conveyor troubles in the furnace, making it possible to manufacture coated arc welding rods more cheaply, efficiently, and without deteriorating quality. Became.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the conventional operating method of the in-furnace conveyor.
Figure 2 is a graph showing the relationship between drying time and quality defect rate of painted arc rods, and Figure 3 is a diagram illustrating the state of painted arc rods on the furnace conveyor when the operating method of the present invention is implemented. It is. 1... Transfer conveyor 2... Collared conveyor 3.
...Upper stage conveyor 4...Magnet 5...Guide conveyor 6...Direction changing section 8...
Lower conveyor 1o...Detection means 11...Control command unit H...Drying furnace a...Painted arc rod A...Painted arc rod group Applicant Kobe Steel, Ltd. Figure 1 111 each Zone stagnation time (intermediate) Figure 3

Claims (1)

[Claims] In a method for operating a conveyor that receives painted arc welding rods conveyed from a paint extruder via a transfer conveyor in an assembly line and conveys them through a drying oven, the above-mentioned A welding rod detection means is disposed, and the detection means determines the presence or absence of the welding rod to start and stop the operation of the conveyor, while the stoppage time at the time of stopping exceeds the allowable stagnation drying time specific to the drying oven. A method for operating a conveyor in a drying oven, characterized in that the operation of the conveyor in the drying oven is automatically restarted at that point.