KR20200103993A - Pipe Drawing Molding Method, Pipe Drawing Device, and Pipe Hot Drawing Process Design Method - Google Patents

Abstract

The present invention relates to a pipe drawing forming method, a pipe drawing device, and a pipe hot-drawing process design method and, more specifically, to a drawing forming method which adjusts a drawing speed of a pipe to be constant in hot drawing forming to improve size precision, a drawing device to apply a compressive force to the rear end of a pipe in a drawing direction in drawing forming, and a process design method capable of optimizing a process condition through finite element analysis. According to an embodiment of the present invention, the pipe drawing device comprises a rear chuck, a front chuck, a heating device, a cooling device, a mold, and a plug, and the pipe drawing forming method comprises: a placing step of placing a pipe on the pipe drawing device; a heating step of heating a portion of the pipe positioned between the rear chuck and the mold at a high frequency after the placing step; a drawing step of moving the front chuck and the rear chuck in a drawing direction after the heating step; a cooling step of cooling a portion of the pipe positioned on the rear end of the mold after the drawing step; and a removal step of removing the pipe from the pipe drawing device after the cooling step of the rear end of the pipe, wherein the heating step, the drawing step, and the cooling step are simultaneously and respectively carried out on the front end, the center, and the rear end of the pipe.

Description

Pipe drawing molding method, pipe drawing device, and pipe hot drawing process design method {Pipe Drawing Molding Method, Pipe Drawing Device, and Pipe Hot Drawing Process Design Method}

The present invention relates to a pipe pultrusion method, a pipe drawing apparatus, and a pipe hot drawing process design method, and more particularly, a pultrusion method for improving dimensional accuracy by constantly adjusting a drawing speed of a pipe during hot drawing, and a drawing The present invention relates to a drawing device that applies a compressive force in the drawing direction to the rear end of a pipe during molding, and a process design method that can optimize process conditions through finite element analysis.

Drawing is a process of reducing or deforming a cross section by pulling a bar or wire between a draw die. The drawn rods and wires are used as transmission shafts, mechanical structural parts, and building members, and the main process variables of drawing are section reduction rate, die angle, friction, and drawing speed. As opposed to drawing, extrusion is a process in which a material is pushed through molds to deform.

Among the pipe manufacturing methods, extrusion manufacturing has the advantage of being able to easily make a desired shape according to the design of a mold, but there is a limitation in that it is difficult to manufacture a pipe having a precise dimension.

In order to improve the dimensional accuracy of the pipe, a method of re-drawing a pipe manufactured by a method such as extrusion is mainly used.

The drawing technology for improving the dimensional precision of pipes has been developed in various shapes and types according to the current use, but the most common drawing pipe manufacturing technology is disclosed in Korean Patent Publication No. 10-1764091 "Pulling Pipe Manufacturing Equipment". Form.

In the case of a conventional pipe hot drawing process, since the temperature of the material is high, as the pipe is increased between the mold and the plug, it is not molded, and a phenomenon of being fixed between the die and the plug (mandrel) occurs.

This lowers the strength of the material (pipe), makes it difficult to mass-produce a uniform product, and the process may not proceed normally and may be interrupted.

Due to the nature of the manufacturing industry, the tact time has a great influence on the unit price of the product, and if the loss time continues to increase due to the sticking phenomenon occurring between processes, a large loss occurs. The need is great.

The problem to be solved by the present invention is to provide a pipe drawing device capable of simultaneously drawing and extruding by providing a press machine at the rear (front end of the pipe) in order to solve the problems of the conventional pipe manufacturing technology as described above. will be.

In addition, a method for forming a pipe through the pipe drawing device and an optimal design method for the forming process are provided.

The present invention in order to solve the problems of the conventional pipe manufacturing technology, in the pipe pultrusion method, the pipe pulling device includes a rear chuck, a front chuck, a heating device, a cooling device, a mold and a plug, and the pipe is the pipe pulling device. A seating step to settle in; After the seating step, a heating step of high-frequency heating a portion located between the rear chuck and the mold of the pipe; After the heating step, a drawing step of moving the front chuck and the rear chuck in the drawing direction; After the drawing step, a cooling step of cooling a portion located at the rear end of the mold of the pipe; The heating step, the drawing step, and the cooling step are performed simultaneously at the front end, the middle end, and the rear end of the pipe, respectively, and after the cooling step of the rear end of the pipe, a stripping step of removing the pipe from the pipe pulling device; Provides.

In addition, the material is stainless steel, the diameter is 80mm to 120mm, it is possible to form a pipe having a thickness of 7mm to 10mm.

In addition, the temperature of the pipe in the heating step may be 750°C to 1100°C, and the temperature in the cooling step may be 0°C to 30°C.

In addition, in the drawing step, the load of the rear chuck may be configured to proceed in a range between 14 tons to 16 tons.

Further, when the rear end of the pipe is in the drawing direction, the rear chuck is fastened to the front end of the pipe so as to apply a load to the front end of the pipe in the drawing direction; A front chuck fastened to the rear end of the pipe to apply a pulling load to the pipe; A mold and a plug contacting the outside and inside of the pipe between the front chuck and the rear chuck; A heating device positioned between the rear chuck and the mold to heat the pipe in high frequency; And a cooling device positioned at the rear end of the mold to cool the formed pipe; Provides a pipe drawing device.

In addition, in the design method of a pipe hot drawing process using the pipe drawing device, an analysis device for modeling the pipe drawing device and performing finite element analysis is provided; A drawing modeling step of modeling a pipe hot drawing process for each condition by using the load of the rear chuck and a reduction rate of the section of the pipe as variables; After the pull-out modeling step, a dimension measuring step of measuring the thickness of the front end, the middle end, and the rear end of the pipe for each condition; After the dimensional measurement step, a dimensional accuracy selection step of selecting condition values satisfying all dimensional tolerances of the front end, the middle end, and the rear end of the pipe; After the dimensional accuracy selection step, a dimensional accuracy selection step of selecting a condition value with high dimensional accuracy by calculating a standard deviation between the thickness of the front end, the middle, and the rear end of the pipe under the corresponding condition for each condition; including, a pipe hot drawing process Provides a design method.

In addition, the drawing speed may be set in the range of 3mm/s to 7mm/s, the reduction rate of the section of the pipe is 5% to 10%, and the load of the rear chuck is 60 tons or less.

According to an embodiment of the present invention, it is possible to improve a material sticking phenomenon occurring between a mold and a plug during a pipe hot pultrusion process.

In addition, it is possible to prevent a decrease in the strength of the material in the pipe hot drawing process.

And, by performing the drawing process at a constant speed, the life/durability of the equipment can be improved, and the dimensional accuracy of the pipe is improved.

In addition, through optimal process design using finite element analysis, it is possible to produce pipes with good pulling speed, dimensional accuracy, dimensional accuracy and physical properties without causing buckling.

1 is a schematic diagram of a pipe drawing apparatus according to an embodiment of the present invention.
2 is a chart measuring the thickness of the front/end/rear end of the pipe manufactured according to each condition of the pipe pultrusion method according to an embodiment of the present invention.
3 is a diagram illustrating a change in speed of a node during a process by selecting a node point of a material (pipe) in the pipe pultrusion method according to an embodiment of the present invention.
4 is a view showing the shape of a mold and a plug in the pipe drawing apparatus according to an embodiment of the present invention.
5 is a view in which nodes are designated in a method for designing a pipe hot drawing process according to an embodiment of the present invention.

Hereinafter, various embodiments of the present document will be described with reference to the accompanying drawings. However, this is not intended to limit the techniques described in this document to specific embodiments, and it is to be understood that various modifications, equivalents, and/or alternatives of the embodiments of this document are included. . In connection with the description of the drawings, similar reference numerals may be used for similar elements.

In this document, expressions such as "have," "may have," "include," or "may contain" are the presence of corresponding features (eg, elements such as numbers, functions, actions, or parts). And does not exclude the presence of additional features.

In this document, expressions such as "A or B," "at least one of A or/and B," or "one or more of A or/and B" may include all possible combinations of the items listed together. . For example, "A or B," "at least one of A and B," or "at least one of A or B" includes (1) at least one A, (2) at least one B, Or (3) it may refer to all cases including both at least one A and at least one B.

Expressions such as "first," "second," "first," or "second," used in this document can modify various elements, regardless of their order and/or importance, and refer to one element. It is used to distinguish it from other components and does not limit the components. For example, a first user device and a second user device may represent different user devices regardless of order or importance. For example, without departing from the scope of the rights described in this document, a first component may be referred to as a second component, and similarly, a second component may be renamed to a first component.

Some component (eg, the first component) is “(functionally or communicatively) coupled with/to” to another component (eg, the second component) When referred to as "connected to", it should be understood that the certain component may be directly connected to the other component, or may be connected through another component (eg, a third component). On the other hand, when a component (eg, a first component) is referred to as being “directly connected” or “directly connected” to another component (eg, a second component), the component and the It may be understood that no other component (eg, a third component) exists between the different components.

The expression "configured to" as used in this document is, for example, "suitable for," "having the capacity to" depending on the situation. ," "designed to," "adapted to," "made to," or "capable of." The term "configured to (or set)" may not necessarily mean only "specifically designed to" in hardware. Instead, in some situations, the expression "a device configured to" may mean that the device "can" along with other devices or parts. For example, the phrase “a processor configured (or configured) to perform A, B, and C” means a dedicated processor (eg, an embedded processor) for performing the operation, or by executing one or more software programs stored in a memory device. , May mean a generic-purpose processor (eg, a CPU or an application processor) capable of performing corresponding operations.

Terms used in this document are only used to describe a specific embodiment, and may not be intended to limit the scope of other embodiments. Singular expressions may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by one of ordinary skill in the technical field described in this document. Among the terms used in this document, terms defined in a general dictionary may be interpreted as having the same or similar meanings as those in the context of the related technology, and unless explicitly defined in this document, an ideal or excessively formal meaning Is not interpreted as. In some cases, even terms defined in this document cannot be interpreted to exclude embodiments of this document.

Various modifications can be made by those of ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims of the present invention, and these modifications are the technical spirit of the present invention. It should not be understood individually from the perspective.

According to an embodiment of the present invention, in the pipe drawing method, the pipe drawing device includes a rear chuck, a front chuck, a heating device, a cooling device, a mold and a plug, and a seating step of seating the pipe in the pipe drawing device; After the seating step, a heating step of high-frequency heating a portion located between the rear chuck and the mold of the pipe; After the heating step, a drawing step of moving the front chuck and the rear chuck in the drawing direction; After the drawing step, a cooling step of cooling a portion located at the rear end of the mold of the pipe; The heating step, the drawing step, and the cooling step are performed simultaneously at the front end, the middle end, and the rear end of the pipe, respectively, and after the cooling step of the rear end of the pipe, a stripping step of removing the pipe from the pipe pulling device; Provides.

In the drawing step, a graph in which a specific part (node) of a pipe (material) is designated and a change in speed during the entire process is measured is shown in FIG. 3. FIG. 5 is a diagram showing an example in which nodes are displayed at an arbitrary position of a pipe (five equally spaced points of the pipe before entering the mold, P1 to P5).

At this time, it can be seen that the distribution of speed is not uniform throughout the process as well as the portion where the molding occurs (the mold entry section).

On the other hand, in the case of the rear chuck, since speed control is difficult, an optimal design is required to maintain a constant speed.

Since the change in the process speed is closely related to the dimensional accuracy of the formed pipe, it is very important to control it to have a constant speed, but it is difficult to keep the overall process speed constant due to the mechanical/physical limitations of the rear chuck.

In an embodiment of the present invention, in order to overcome the difficulty in maintaining the process speed as described above, a condition in which the process speed is kept as constant as possible through an optimal design is set.

In addition, the material is stainless steel, the diameter is 80mm to 120mm, it is possible to form a pipe having a thickness of 7mm to 10mm.

In the embodiment of the present invention, SUS316L was used as a material.

In addition, the temperature of the pipe in the heating step may be 750°C to 1100°C, and the temperature in the cooling step may be 0°C to 30°C.

In the cooling step, natural cooling at room temperature (room temperature) or cooling using cooling water may be used. In this case, the cooling device may include a blower and a cooling water supply device.

The temperature of the pipe in the heating step means the temperature of the pipe itself, and the temperature in the cooling step means the temperature of the cooling device. Even if the pipe is cooled with a cooling device, the temperature of the pipe itself may differ from the range of 0 to 30 degrees.

In addition, in the drawing step, the load of the rear chuck may be configured to proceed in a range between 14 tons to 16 tons.

If the compressive load of the rear chuck is too large (more than 30 tons), buckling occurs at the front end of the pipe (around the rear-chuck joint), so it is a load large enough to prevent sticking and is the optimum condition in which buckling does not occur in the pipe. The drawing step can be performed in the same pressure range.

If the pressure is too high, in addition to buckling, material buildup may occur between the mold and the plug.

Further, when the rear end of the pipe is in the drawing direction, the rear chuck is fastened to the front end of the pipe so as to apply a load to the front end of the pipe in the drawing direction; A front chuck fastened to the rear end of the pipe to apply a pulling load to the pipe; A mold and a plug contacting the outside and inside of the pipe between the front chuck and the rear chuck; A heating device positioned between the rear chuck and the mold to heat the pipe in high frequency; And a cooling device positioned at the rear end of the mold to cool the formed pipe; Provides a pipe drawing device.

In the pipe forming conditions according to the embodiment of the present invention, it is preferable that the radius of the arc formed at the mold inlet (die) is 65 mm (range from 60 mm to 70 mm). An arc (R) formed at the entrance of the mold is shown in FIG. It is preferable that the plug angle A is composed of 5 degrees (range 4 to 6 degrees). It is possible to configure it outside the above-described range, but the optimum processing results (processing speed, deformation, strength, processing precision, etc.) were derived within the above range.

The rear chuck may be configured to be inserted into the inside of the pipe, contact the inner circumferential surface of the pipe, and apply a force in the direction of the outer circumferential surface of the pipe to fix the pipe.

In addition, in the design method of a pipe hot drawing process using the pipe drawing device, an analysis device for modeling the pipe drawing device and performing finite element analysis is provided; A drawing modeling step of modeling a pipe hot drawing process for each condition by using the load of the rear chuck and a reduction rate of the section of the pipe as variables; After the pull-out modeling step, a dimension measuring step of measuring the thickness of the front end, the middle end, and the rear end of the pipe for each condition; After the dimensional measurement step, a dimensional accuracy selection step of selecting condition values satisfying all dimensional tolerances of the front end, the middle end, and the rear end of the pipe; After the dimensional accuracy selection step, a dimensional accuracy selection step of selecting a condition value with high dimensional accuracy by calculating a standard deviation between the thickness of the front end, the middle, and the rear end of the pipe under the corresponding condition for each condition; including, a pipe hot drawing process Provides a design method.

Table 1 below is an example of a test, and under the following conditions, the dimensional accuracy and dimensional accuracy were measured to be the highest at a pulling speed of 5 mm/s and a load of 15 Ton.

Drawing speed [mm/s] Sectional reduction rate [%] Load [Ton] Case1 5 5 One Case2 5 5 5 Case3 5 5 10 Case4 5 5 15 Case5 5 5 30 Case6 5 5 60 Case7 5 10 One Case8 5 10 5 Case9 5 10 10 Case10 5 10 15 Case11 5 10 30 Case12 5 10 60

2 shows the pipe thickness when tested under the same conditions as described above. At the target thickness of 8.075mm, the dimensional tolerance of 0.75% must be satisfied, so the lower limit of the thickness is 8.015mm. At this time, in Case A, it is not a suitable condition because it is outside the dimensional tolerance range at the rear end of the pipe.

The front/end/rear ends of Cases B to D all satisfy dimensional tolerances, but there are differences in dimensional accuracy and dimensional accuracy. Case D, where the average value of the front end/stop/rear end is closest to 8.075mm, has the highest dimensional accuracy, and Case C, which has the smallest standard deviation of the front end/stop/rear end, is high.

According to the use environment and purpose of the pipe, the optimal conditions can be selected by varying the weights of dimensional accuracy and dimensional accuracy. In the case of manufacturing pipes used where average thickness is important rather than the difference in thickness of the front/end/rear end, a high weight is given to the dimensional accuracy. Can be given a high weight.

In addition, the pulling speed may be set in the range of 3mm/s to 7mm/s, the reduction rate of the section of the pipe is 5% to 10%, and the load of the rear chuck is 60 tons or less.

1: rear chuck
2: front chuck
3: pipe
31: pipe shear
32: pipe interruption
33: pipe rear end
4: Die
5: Plug, Mandrel
H: heating section
C: cooling section
R: radius of mold inlet
A: Plug each

Claims (8)

In the pipe pultrusion method,
The pipe drawing device includes a rear chuck, a front chuck, a heating device, a cooling device, a mold and a plug,
A seating step of seating a pipe in the pipe drawing device;
After the seating step, a heating step of high-frequency heating a portion located between the rear chuck and the mold of the pipe;
After the heating step, a drawing step of moving the front chuck and the rear chuck in the drawing direction;
After the drawing step, a cooling step of cooling a portion located at the rear end of the mold of the pipe;
The heating step, the drawing step and the cooling step are performed simultaneously at the front end, the middle end and the rear end of the pipe, respectively,
After the cooling step of the rear end of the pipe, a removing step of removing the pipe from the pipe drawing device; including, pipe pultrusion method The method of claim 1,
The material of the pipe is stainless steel, the diameter of the pipe is 80mm to 120mm, and the thickness of the pipe is 7mm to 10mm, pipe pultrusion method The method of claim 2,
The pipe temperature in the heating step is 750 degrees to 1100 degrees,
The temperature of the cooling step is characterized in that 0 to 30 degrees, pipe pultrusion method The method of claim 3,
In the drawing step, the load of the rear chuck is characterized in that it proceeds in a range between 14 to 16 tons, pipe drawing method A rear chuck fastened to the front end of the pipe to apply a load to the front end of the pipe in the pulling direction when the rear end of the pipe is in the drawing direction;
A front chuck fastened to the rear end of the pipe to apply a pulling load to the pipe;
A mold and a plug contacting the outside and inside of the pipe between the front chuck and the rear chuck;
A heating device positioned between the rear chuck and the mold to heat the pipe in high frequency;
And a cooling device positioned at the rear end of the mold to cool the formed pipe; Pipe drawing device In the design method of the pipe hot drawing process using the pipe drawing device of claim 5,
An analysis device for modeling the pipe drawing device and performing finite element analysis;
A drawing modeling step of modeling a pipe hot drawing process for each condition by using the load of the rear chuck and a reduction rate of the section of the pipe as variables;
After the pull-out modeling step, a dimension measuring step of measuring the thickness of the front end, the middle end, and the rear end of the pipe for each condition;
After the dimensional measurement step, a dimensional accuracy selection step of selecting condition values satisfying all dimensional tolerances of the front end, the middle end, and the rear end of the pipe;
After the dimensional accuracy selection step, a dimensional accuracy selection step of selecting a condition value having high dimensional accuracy by calculating a standard deviation between the thickness of the front end, the middle, and the rear end of the pipe under the corresponding condition for each condition; including, a pipe hot drawing process Design method The method of claim 6,
The material of the pipe is stainless steel,
The diameter of the pipe is 80mm to 120mm,
The thickness of the pipe is 7mm to 10mm,
The pipe temperature in the heating step is 750 degrees to 1100 degrees,
The temperature of the cooling step is characterized in that the temperature is 0 to 30 degrees, pipe hot drawing process design method The method of claim 7,
The drawing speed is 3mm/s to 7mm/s,
The reduction rate of the section of the pipe is 5% to 10%,
The load of the rear chuck is characterized in that set in the range of 60 tons or less, pipe hot drawing process design method

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