Method for controlling and rolling bell end of pipe die through periodic rolling mill

Abstract

The invention discloses a method for controlling and rolling a pipe die bellmouth end through a periodic rolling mill. The method comprises the steps that S1, a round steel billet is perforated through Mangnow cross rolling, and a perforated tubular billet with the diameter not smaller than that of the pipe die bellmouth end is obtained; s2, performing periodic rolling on the perforated tubular billet by adopting a periodic rolling mill, wherein the periodic rolling mill rolls a straight pipe part not smaller than the pipe die; and S3, a Pilger head with the length not smaller than the length of the pipe die socket end is reserved in a periodic rolling mill, a stop controller is installed at the corresponding position of a sliding table base, when rolling is conducted to a certain position of the tail, the sliding table stops advancing, rolling is finished, and a pipe die blank with the accurate socket end length is obtained. According to the method, the complex forming process of pushing hot expansion or surfacing repair welding of the horn mouth of the pipe die socket end is omitted, the pipe die blank with the length of the horn-shaped socket end is directly obtained by controlling the rolling process, the material utilization rate is greatly increased, the pipe die technological process is simplified, the production efficiency is improved, the production period is shortened, and the cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of rolled pipes, and in particular to a method for a periodic rolling mill to control a bell end of a rolled pipe die. Background Art

[0002] Ductile iron pipes are mainly called centrifugal ductile iron pipes. They have the essence of iron and the properties of steel, excellent corrosion resistance, good ductility, good sealing effect, easy installation, and are widely used in municipal, industrial and mining enterprises' water supply, gas transmission, oil transmission and other livelihood projects.

[0003] The forming method of ductile iron pipe is to inject spheroidal graphite molten iron into the ductile iron pipe mold (referred to as "pipe mold"), and then cast it by high-speed rotating centrifugal casting. Its structure is a straight pipe plus a trumpet-shaped connection (referred to as "bell end"). The appearance of the ductile iron pipe is completely determined by the shape and size of the pipe mold. The structure of the pipe mold is a straight pipe plus a bell end, and it has a certain wall thickness. The whole seamless steel pipe cannot be formed in one step by a steel pipe rolling mill in the traditional pipe mold manufacturing method due to its special structure. It is necessary to add deformation methods or surfacing supplementary metal on the basis of the seamless steel pipe to obtain the ideal shape. Specifically, a conical inner mold is used for pushing and hot expansion to form a bell mouth, or surfacing supplementary metal to form an external bell mouth, and then the bell-shaped bell end can be processed and manufactured. The above two processes have the disadvantages of complex manufacturing process, high manufacturing cost, long manufacturing cycle, and low manufacturing efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide a method for controlling the bell end of a rolling tube mold by a cyclic rolling mill, so as to solve the technical problems of complex manufacturing process, high manufacturing cost, long manufacturing cycle and low manufacturing efficiency in the prior art of tube mold manufacturing.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for controlling the bell end of a rolling tube die by a periodic rolling mill, comprising the following steps:

[0007] S1, the round steel billet is perforated by Mannheim oblique rolling to obtain a perforated rough pipe with a diameter not less than the socket end of the pipe mold;

[0008] S2. The perforated rough pipe is periodically rolled by a periodic rolling mill, and the periodic rolling mill rolls out a straight pipe portion not smaller than the pipe die;

[0009] S3. The periodic rolling mill leaves a pilger head that is not less than the length of the socket end of the tube mold, and installs a stop controller at the corresponding position of the slide base. When the rolling reaches a certain position at the tail end, the slide stops moving forward, and the rolling is completed, obtaining a tube mold blank with an accurate socket end length.

[0010] Furthermore, the size of the round steel billet is 785mm*d110mm*1860mm, and the size of the perforated rough tube is 796mm*d524mm*3300mm.

[0011] Furthermore, the perforated capillary tube is 15 to 30 mm larger than the diameter of the socket end of the tube mold.

[0012] Furthermore, the size of the socket end of the pipe mold is D780-786mm*d519-528mm*L330-340mm, and the size of the pipe mold is D627-632mm*d503-506mm.

[0013] Furthermore, in the rolling process of the cyclic rolling mill in S2, the rolled piece is fed into the die through a feeder, rolled through a forging strip, a finishing strip, and a final rolling strip, and rolled back in the reverse direction, and then punched out by rotating 90°±5° in the empty rolling strip to carry out the next cycle of rolling. The perforated rough pipe is formed through several cycles of rolling.

[0014] Based on the above technical solution, the embodiments of the present invention can at least produce the following technical effects:

[0015] The present invention eliminates the complicated forming process of pushing, hot expanding or surfacing welding of the bell mouth of the pipe mold socket end, and directly obtains a pipe mold blank with a trumpet-shaped bell end length by controlling the rolling process, which not only greatly improves the material utilization rate but also simplifies the pipe mold process flow, improves production efficiency, shortens the production cycle and saves costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0017] Figure 1 This is a diagram of a blank punching hole according to an embodiment of the present invention;

[0018] Figure 2 is a Mann-type oblique rolling perforation diagram of an embodiment of the present invention;

[0019] Figure 3 Schematic diagram of the tube die rolling process for controlling the length of the socket end according to an embodiment of the present invention;

[0020] Figure 4 It is a schematic diagram of the rolling process of a tube die for controlling the length of the socket end according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0022] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0023] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0024] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0025] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0026] Example 1

[0027] like Figure 1-4 As shown, a method for controlling the bell end of a rolling tube die by a periodic rolling mill comprises the following steps:

[0028] S1, the round steel billet is perforated by Mannheim oblique rolling to obtain a perforated rough pipe with a diameter not less than the socket end of the pipe mold;

[0029] S2. The perforated rough pipe is periodically rolled by a periodic rolling mill, and the periodic rolling mill rolls out a straight pipe portion not smaller than the pipe die;

[0030] S3. The periodic rolling mill leaves a pilger head that is not less than the length of the socket end of the tube mold, and installs a stop controller at the corresponding position of the slide base. When the rolling reaches a certain position at the tail end, the slide stops moving forward, and the rolling is completed, obtaining a tube mold blank with an accurate socket end length.

[0031] Select the appropriate size and weight of the round steel billet, and use Mann oblique rolling to perforate the pipe with a reasonable processing allowance (15-30mm larger than the diameter of the pipe die socket end), and then use a periodic rolling mill (pilger mill) to perform periodic rolling on the perforated pipe for the main deformation. The periodic rolling mill needs to combine the roller hole type, piston rod stroke and slide feed amount to accurately calculate the required pilger head length, that is, the length of the pipe die socket end, and then install a stop controller at the corresponding position of the slide base. When the rolling reaches a certain position at the tail (the position of the feeder travel stop controller), the slide stops moving, and the rolling ends, and a pipe die blank with an accurate socket end length is obtained.

[0032] A DN500 pipe mold tube with a socket end length of 150mm, made of 21CrMo10, with a pipe body size of OD625×ID510 and a socket end size of OD780×ID510×L330 (including R arc length), which is obliquely perforated by a piercing machine and rolled by a periodic rolling mill.

[0033] The perforation parameters are shown in Table 1 below, and the cycle rolling parameters are shown in Table 2 below.

[0034] Table 1 Perforation parameters

[0035]

[0036] Table 2 Cycle rolling parameters

[0037]

[0038] The inspection data of the tube mold after cooling the flat head is shown in Table 3 below.

[0039] Table 3 Pipe mold inspection data

[0040]

[0041] Finally, it should be noted that:

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling the bell end of a rolling tube die in a periodic rolling mill, characterized in that: The following steps are involved: S1, the round steel billet is perforated by Mannheim oblique rolling to obtain a perforated rough pipe with a diameter not less than the socket end of the pipe mold; S2. The perforated rough pipe is periodically rolled by a periodic rolling mill, and the periodic rolling mill rolls out a straight pipe portion not smaller than the pipe die; S3. The periodic rolling mill leaves a pilger head that is not less than the length of the socket end of the tube mold, and installs a stop controller at the corresponding position of the slide base. When the rolling reaches a certain position at the tail end, the slide stops moving forward, and the rolling is completed, obtaining a tube mold blank with an accurate socket end length.

2. The method for controlling the bell end of a tube die in a periodic rolling mill according to claim 1, characterized in that: The size of the round steel billet is 785mm*d110mm*1860mm, and the size of the perforated rough tube is 796mm*d524mm*3300mm.

3. The method for controlling the bell end of a tube die in a periodic rolling mill according to claim 1, characterized in that: The perforated capillary tube is 15 to 30 mm larger than the diameter of the socket end of the tube mold.

4. The method for controlling the bell end of a tube die in a periodic rolling mill according to claim 1, characterized in that: The size of the socket end of the pipe mold is D780-786mm*d519-528mm*L330-340mm, and the size of the pipe mold is D627-632mm*d503-506mm.

5. The method for controlling the bell end of a tube die in a periodic rolling mill according to claim 1, characterized in that: The rolling process of the rolling mill in the S2 cycle is as follows: the rolled piece is fed into the die through the feeder, rolled through the forging strip, finishing strip, and final rolling strip, and rolled back in the reverse direction, and then punched out by rotating 90°±5° in the empty rolling strip to carry out the next cycle of rolling. The perforated rough pipe is formed through several cycles of rolling.

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