JPS6016493B2 - Heat treatment equipment for cast iron pipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new heat treatment apparatus for manufacturing cast iron pipes having a ferritic structure.

Ductile cast iron pipes made by centrifugal force casting have a brittle structure that contains a large amount of cementite or pearlite when they are pulled out of the metal frame at high temperatures after casting. teeth,
It is customary to separately transport and charge the cast iron pipe, which has been cooled to near room temperature, into a heat treatment furnace, hold it at, for example, 950 q C for 1 to 2 hours, and then slowly cool it to perform ferritization and phosphorus annealing.

However, in the case of such conventional heat treatment methods, since the once cooled cast iron pipe is reheated and annealed, there is a huge waste of thermal energy, and at the same time, there is a drawback that productivity also decreases. In addition, in the case of a rotary furnace, the scale of the furnace itself increases, and a transport route and transport device for the cast iron pipes are required, and the ancillary equipment for heat treatment occupies a large space and requires expensive equipment costs. There were some drawbacks.

The present invention is a heat treatment device for cast iron pipes using centrifugal casting.
It is an object of the present invention to provide a suitable device capable of solving the above-mentioned drawbacks and problems, and in which a heat treatment furnace is integrated in the vicinity of the extension direction of the side where the cast iron pipe is extruded in the far D force casting machine of the present invention. The heat treatment furnace group is provided with a plurality of heat treatment furnaces, each of which is directly charged with red-hot cast iron pipes from a casting machine, arranged in parallel in the direction of movement. , the casting machine side of each heat treatment furnace is equipped with a diamond inlet that receives cast iron pipes from the casting machine opposite to the side where the cast iron pipes are extruded in the casting machine by the movement of the heat treatment furnace group, and each heat treatment furnace is equipped with It is characterized by comprising a rotating means for housing the tube in a rotating state and a heating means for adjusting the ambient temperature.

The present invention will be explained below based on the embodiments shown in FIGS. 1 and 2.

In the figure, 1' is composed of a metal frame 2 for casting ductile cast iron pipes, which is usually coated with a fireproof coating on the inner surface, and a rotating device 4 that rotates the metal frame 2 with a positioning layer via rotating rollers 3. The centrifugal casting machine is equipped with a Western-style hot water trolley 7 equipped with a ladle 6 for pouring hot water into the metal frame 2 through a trough 5 on the coin side. For example, as shown in the figure, a push-out cart 10 is provided with a push-out rod 9 for pushing out the solidified cast iron pipe 8 in a red-hot state toward the opposite side of the casting machine 1. Both are arranged in parallel at the extended end of the laid rail 11, and are alternately brought close to the casting machine 1 as required. Reference numeral 12 denotes a heat treatment furnace group that is movably arranged in the direction perpendicular to the direction of extension of the casting machine 1 in the vicinity of the direction of extension of the casting machine 1 opposite to the mirror-containing side. A box-shaped single furnace body 12' made of a refractory material is defined by a partition wall 13, and a first heat treatment furnace 14, a second heat treatment furnace 15, and a third heat treatment furnace 16 are arranged in parallel in the direction of movement.
Three batch type furnaces are arranged, and the furnace body 12'
The casting machine 1 is constructed entirely of a trolley structure with wheels 17 provided at the bottom, and is movable on rails 18 laid in a direction perpendicular to the direction in which the casting machine 1 extends.

In this embodiment, a case is illustrated in which the heat treatment furnace group 12 defines a single furnace body 12' and each heat treatment furnace 14, 15, 16 is arranged. It may be a collection of independent batch-type heat treatment furnaces that are movable in the direction, and the number of heat treatment furnaces constituting the heat treatment furnace group 12 may be any number of plurality as desired, in addition to the above case. can.

Each heat treatment furnace 14, 15, which constitutes the heat treatment furnace group 12,
16, each furnace has, of course, on the casting machine 1 side and on the opposite side, a charging inlet and an outlet (both not shown) that can be opened and closed for charging the cast iron pipe 8 into the furnace and taking it out of the furnace. At the same time, each furnace is equipped with a casting machine 1 (
The red-hot cast iron pipes 8 are sequentially inserted directly into the frame by pushing out the push rod 9 from the metal frame 2).

In addition, each heat treatment furnace 14, 15, 16 is provided with a cast iron pipe 8 in order to prevent deformation, especially ovalization, of the cast iron pipe 8 in a red-hot state.
The cast iron pipe 8 is provided with a rotating means for holding it under a rotating state, and a heating means for adjusting the ambient temperature of the cast iron pipe 8 in order to achieve the desired ferritization inscription.

That is, in the figure, reference numeral 19 denotes rotating rollers which are arranged in pairs in each furnace, as a means for rotating the cast iron pipe 8, and are driven by a rotating device 20 fixed to the bottom of the furnace. 8 is structurally supported on this rotating roller 9, and is maintained in its rotational state in its normal position.

Further, reference numeral 21 indicates heating burners (not shown in Fig. 1) arranged in several places in each furnace facing into the furnace from the furnace ceiling as a suitable heating means. This can be adjusted individually. Furthermore, in the case of this embodiment, in order to facilitate the charging of the cast iron pipe 8 into the furnace and the time of taking it out of the furnace, the following means for assisting the movement of the cast iron pipe 8 is provided in the furnace. It is being

That is, as shown in the figure, each furnace is provided with a pair of extendable and retractable cylinder rods 23 projecting upward from the floor surface thereof in the front, rear, left and right directions, and with the ends of the left and right pairs connected by a connecting village 22. When loading and unloading the tube 8, the cast iron tube 8 can be moved while being pushed up onto the rotating rollers 19 via the connecting village 22. The rotating roller 9, cylinder rod 23, and connecting punch 22 installed in the furnace are required to withstand high-temperature use, so for example, the rotating loaf 19 is water-cooled, while the rod 23 and connecting punch 22 are Preferably, it is coated with an insulating and refractory material such as ceramic fiber.

As the rotating means and heating means for the cast iron pipe 8 employed in the heat treatment apparatus of the present invention, the above-mentioned ones are presented as preferred examples, but in the present invention, it is of course possible to use other configurations for each of these means. This does not prevent recruitment.

On the opposite side of the heat treatment furnace group 12 from the casting machine 1, there is a
After the cast iron pipe 8 has undergone the required heat treatment in the furnace, a means for taking it out of the furnace is installed. That is, in the figure, 24 is a take-out device that pulls out the cast iron pipe 8 from the furnace through a drawer 26 hung from the end of the cast iron pipe 8 from a winch 25 at the rear. , are arranged movably in the direction of movement of the heat treatment furnace group 12 so that the cast iron pipes 8 can be sequentially taken out from each furnace. The cast iron pipes 8 taken out from each furnace by such a take-out device 24 are guided by a plurality of pairs of guide rails 2 laid in parallel in the drawing direction.
After being pulled out along the guide rail 27, the paper is transferred onto a transfer table 29 on which a plurality of rails 28 are arranged in parallel perpendicular to the guide rail 27. Incidentally, when the cast iron pipe 8 is taken out of the furnace, its temperature is considerably lowered, and there is no possibility of deformation such as ovalization. The case where the required competitive annealing heat treatment for ferritization is applied to a centrifugally cast ductile cast iron pipe using the heat treatment apparatus of the present invention described above based on the preferred embodiment will be described. According to the apparatus of the present invention, the cast iron pipe 8 The caster 1 is charged into each furnace in a red-hot state, and of course is continuously phosphorized during the cooling process.

At this time, regarding the annealing conditions to be applied to the cast iron pipe 8 in the furnace, one method is to annealing the cast iron pipe 8 from 800 qo to 6500 qo, for example.
There is a method of slow cooling down to 0. Another method is to cool the cast iron pipe 8
There is a method of maintaining the temperature at approximately 750 pm. In any of these methods, the cast iron pipe 8 has its Ar, transformation point (
Since it is slowly cooled at around 750℃, sufficient ferrite formation is achieved, and compared to the conventional heat treatment method in which reheating is performed in a separate heat treatment furnace, the structure is sufficiently ferrite. What you get is what you get.

Now, to explain this heat treatment effect by citing a specific example, the pipe size is 10,000 x 6,000 x 13. A ductile cast iron pipe with a chemical composition of 3.3% C, 2.8% Si, 0.03% Mg, and the remainder substantially Fe was heated under the dull conditions shown in Fig. 3 (cast iron pipe charging temperature 800q0, Removal overflow degree 650℃
According to an actual example of a cast iron pipe that is heat treated at a rolling speed of 10:0/skin), a ferrite content of 97% is achieved, and its mechanical properties are as follows: tensile strength of 5.9k9/h, elongation. 18%, and a V-notch Charby impact value of 1.7k9m/ was secured.

Also, the pipe dimensions are the same as the above, and the chemical composition is C3.4%, S
A ductile cast iron pipe consisting of 2.8% i, 0.03% Mg, and the balance substantially Fe was annealed under the annealing conditions (750o
According to an example of heat treatment, a cast iron pipe has a ferrite content of 94%, and its mechanical properties have a tensile strength of 60 kg/rail, an elongation of 16%, and a V-notch Charpy impact resistance. 1.6 kgm/m was secured. The anchor conditions in each heat treatment furnace in the heat treatment furnace group 12 are most suitable when only ferritization and dulling are performed as described above. , the temperature of the molten metal, charging temperature, inoculation state, etc. are changed individually for each furnace from time to time, and in this case, the heating means provided in each furnace
It is also possible to perform two stages of graphitization, which decomposes cementite, and ferritization annealing, which decomposes pearlite, by adjusting the ambient temperature.

The device of the present invention, needless to say, utilizes the self-retained heat of the cast iron pipe 8, and therefore requires only a small amount of thermal energy to heat each of the furnaces. In a state where the inside of the furnace is maintained at a predetermined set temperature by the heat radiation, no special heating is required. Since the apparatus of the present invention is equipped with a plurality of heat treatment furnaces (the number of furnaces is determined as necessary), the cast iron pipe production rate of the casting machine 1 is equal to the processing rate required for the heat treatment. Even under normal operation, the cast iron pipe 8 is sequentially distributed and charged into different heat treatment furnaces through the movement of the heat treatment furnace group 12, so that there is no delay in the heat treatment process.

According to the cast iron pipe processing apparatus of the present invention as described above, it is of course effective as an apparatus for obtaining the desired ferrite structure in a ductile cast iron pipe that has been centrifugally cast. Red-hot cast iron pipes are then distributed and directly charged into each furnace of a group of heat treatment furnaces arranged in a freely movable manner through a normal extrusion device.
There is no need for any conveyance routes or conveyance equipment, and the entire heat treatment furnace group is extremely compact compared to conventional horizontal rotary furnaces.Moreover, it is a continuous process from centrifugal casting of cast iron pipes.
Since heat treatment is performed using the self-retained heat, it is extremely energy efficient compared to reheating. In addition, in the device of the present invention, cast iron pipes cast by a casting machine are used in the distribution system. As the cast iron pipe is equipped with multiple heat treatment furnaces, the heat treatment can fully follow the production of the casting machine, which in turn results in high productivity. Since it can be accommodated in a rotating state in each furnace, the inconvenient problem of deformation, especially ovalization, is reliably solved.

Further, an integrated heat treatment furnace group is provided in the vicinity of the extension direction on the side where the cast iron pipe is extruded in the far-D force casting machine, and is movable in a direction orthogonal to the above-mentioned extension direction, and a plurality of heat treatment furnaces are provided in the heat treatment furnace group. The heat treatment furnaces are arranged in parallel in the moving direction, and the cast iron pipe from the casting machine is received on the casting machine side of each heat treatment furnace, facing the side from which the cast iron pipe in the casting machine is extruded by the movement of the heat treatment furnace group. Since the charging port is provided, the space for the heat treatment furnace group including the movement space can be reduced, and the space of the entire equipment can be reduced. Furthermore, since the integrated heat treatment furnace group is moved as described above, a single means for moving the heat treatment furnace group is sufficient, and the movement of the heat treatment furnace group can be easily controlled.

[Brief explanation of drawings]

Fig. 1 is a plan view showing an embodiment of the device of the present invention, Fig. 2 is a side view of the same cross section, and Figs. be. DESCRIPTION OF SYMBOLS 1... Centrifugal casting machine, 8... Cast iron pipe, 12... Heat treatment furnace group, 14, 15, 16... 1st heat treatment furnace, 2nd
... Heat treatment furnace, 3rd ... Heat treatment furnace, 19 ... Rotating loaf, 20 ... Rotating device, 21 ... Heating burner. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. An integrated heat treatment furnace group is provided near the extension direction of the side where the cast iron pipe is extruded in the centrifugal force casting machine, and is movable in a direction orthogonal to the extension direction, and each of the heat treatment furnaces is connected to the cast iron pipe from the casting machine. A plurality of heat treatment furnaces into which red-hot cast iron pipes are directly charged are arranged in parallel in the direction of movement, and the cast iron pipes in the casting machine are extruded by the movement of the heat treatment furnace group to the casting machine side of each heat treatment furnace. Each heat treatment furnace is equipped with a charging port for receiving the cast iron pipe from the casting machine opposite to the side where the pipe is to be processed, and each heat treatment furnace is equipped with a rotating means for accommodating the cast iron pipe in a rotating state and a heating means for adjusting the ambient temperature. A heat treatment device for cast iron pipes, which is characterized by the following: