JPH02220702A - Method for preventing over-filing of press roll piercer - Google Patents

Abstract

PURPOSE:To stabilize the quality of a low-deformation resistance material by executing the control to change a roll speed and a pusher speed at a specific satisfactory relation. CONSTITUTION:A plug 2 is located at the center of the hollow circular pass of a pair of caliber rolls for piercing. A billet having a square section is pushed by the pusher into the hollow circular pass and is thereby pierced, by which a hollow stock pipe (pierced material) 3 is formed. The control to change one or both of the roll speed and pusher speed so as to keep the coefft. alpha expressed by equation I in a 1.1 to 1.3 range is executed. In the equation I, Vr: roll speed, Vp; the speed of pushing the billet having the square section (pusher speed), lambda: the elongation of the material. The square section billet, the sectional size L of which decreases gradually by 0.80 to 0.95L per 1m in the axial direction of the billet, is used is a starting material. The over-filling of the press roll piercer is suppressed within a permissible range in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for preventing biting and extrusion in press roll piercers.

[Prior Art] As is well known, a press roll piercer (hereinafter abbreviated as PRP) presses a billet with a Gf square IE5 cross section in the direction of the pass line and applies a force to the outside surface. This is a perforation machine that presses down circularly with a pair of caliber rolls and perforates the inner surface with a plug placed at the center of the rolls. When rolling a material with low deformation resistance or a large width expansion, such as titanium, with this punching machine, bite-out becomes a problem.

An example of such a case is shown in FIG. In the figure, the protrusion K of the perforated material 3 that occurs at the opening of the caliber roll 1 is a protrusion, and if this protrusion is large, it cannot be transported to the next process, and the protrusion may cause defects on the outer surface in the next process. This poses a major problem in terms of work and quality.

[Problem to be Solved by the Invention] Therefore, the problem to be solved by the present invention is to prevent the problem of biting when drilling low deformation resistant materials with a press roll piercer, and to perform stable work. and to achieve quality improvement.

[Means for Solving the Problems] The gist of the present invention is as follows: 1. A plug supported by a bar is positioned at the center of a circular path formed by a pair of rolls having a semicircular caliber to form a hollow circle. In the press roll piercing rolling process in which a billet with a square cross section is pushed into the hollow circular path in the longitudinal direction of the billet by a pusher and piercing rolled to form a hollow tube, the coefficient α expressed by the following formula is set to 1.1. A method for preventing biting in a press roll piercer, characterized by controlling one or both of a roll speed and a pusher speed to be controlled to a range of 1.3 to 1.3.

α=Vr/(λ・Vp) Where, v': Roll speed Vp: Square cross section billet pushing speed (pusher speed) λ: Stretching of material 2, circular path formed by a pair of rolls with semicircular caliber A plug supported by a bar is positioned at the center of the hole to form a hollow circular path, and a billet with a square cross section is pushed into the hollow circular path in the longitudinal direction of the billet by a pusher to perforate and roll it into a hollow tube. In the rolling process, the cross-sectional width dimension of the square cross-section billet is O, aO ~ 0.95 L per 1 m in the billet ha direction.
A method for preventing bite in a press roll piercer, characterized in that a starting material is a material that gradually shrinks within a range of .

It is in.

[Details of the Invention] Hereinafter, the present invention will be described in detail by taking the perforation of titanium as an example.

In the case of titanium, as shown in FIG. 2, the deformation resistance at high temperatures decreases as the temperature increases, and since it is lower than the deformation resistance of ordinary steel, it tends to bite more easily than ordinary steel. Lowering the perforation temperature is considered to be effective in preventing biting, but since the seamless hot rolling process involves rolling in a subsequent mill after perforation, it is desirable to perform perforation at as high a temperature as possible, so another countermeasure is needed. is necessary.

As a result of a detailed study of the tendency of this protrusion, the inventors found that the protrusion increases as the drilling process progresses.The cause of this is that bulging occurs from the rear end of the perforated material by the pusher as the drilling process progresses, and the material entrance speed increases. It was found that this is because the roll speed becomes unmatched and bulging is further promoted. Further studies revealed that by gradually reducing the pushing speed during drilling, bulging of the drilling material during drilling can be prevented and stable drilling can be achieved. In PRP, the drilling state is determined by the roll speed and the pusher pushing speed, but the drilling conditions are set based on the coefficient α defined below, and normally the drilling is performed with α=approximately 1.0 throughout the drilling.

(However, Vr: roll speed, Vp: pushing speed, λ: material stretching) The Vp setting value to prevent biting is 1 m of perforated material.
On the other hand, when α=1.0 at the start of drilling, α=1.10 to 1.30 at the completion of drilling. In this case, α=
If it is less than 1.10, there is no sufficient bite prevention effect, and α=1. : If it is 10 or more, the perforation becomes unstable due to roll-based perforation.

In addition, in the above case, an example was shown in which the pushing speed (pusher speed) of the square section billet was controlled, but in the present invention, even if the roll speed is changed or both the pushing speed and the roll speed are controlled. Similar effects can be expected.

The inventors focused on a perforated material as another method of preventing chewing, and clarified that it is possible to prevent chewing in the same way by gradually narrowing the side surface corresponding to the roll gap in the longitudinal direction in advance. I made it. The perforated material in this case is
The vertical dimension does not change, but the horizontal dimension changes from the tip to the rear end, but the amount of change is -
When the length of the side is L, 0.0 mm per 1 m in the axial direction of the perforated material.
80-0.95L is appropriate. - If the side is 0.95L or more, the effect cannot be fully exhibited, and if the side is 0.80L or less, it will be underfilled.

[Example] (Example 1) As an example of the present invention, under the following drilling conditions, the roll speed was kept constant, the pusher pushing speed was gradually changed from α = 1.0 at the start of drilling, and drilling was performed. The test was conducted by changing the α value at the time of completion from 1.0 to 1.4.

I investigated the situation at that time.

(1) Testing machine: Model press roll viaser = (2) Perforation material; Size 80x 1000m100O Material Titanium (3) Finished dimensions: Outer diameter 93ffIIIφX Wall thickness 23.
3mm (4) Drilling temperature: 1100°C (5) Plug diameter: 46.501mφ As shown in Table 1, a tolerance range of 3.0+nm or less for the protrusion amount can be achieved when α=1.1 or more, and α ;1.3
Stable drilling without occurrence of slip etc. could be carried out as follows.

Table 1 (Example 2) As an example of the present invention, the width of the rear end of the perforated material was gradually changed from the front end, and the width of the rear end was changed from 0.75 at the front end to 1.0. The state of biting was examined under the same drilling conditions as in Example 1. Table 2 shows the amount of bite at that time.If the width of the leading end is L, the amount of bite could be kept within the allowable range by setting the width of the rear end to 0.95 or less. However, at 0.75L, the hole is not filled.

Table 2 However, its industrial effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the state of biting out, and the amount of biting out. FIG. 2 is a diagram showing the deformation resistance of titanium material at high temperatures. 1... Caliber roll for drilling, 2... Plug, 3...
・・Perforated material, ・・Bite amount

Claims (1)

[Claims] 1. A plug supported by a bar is positioned at the center of a circular path formed by a pair of rolls having a semicircular caliber to form a hollow circular path, and an angular cross section is formed in the hollow circular path. In the press roll piercing rolling process in which the billet is pushed in the billet length direction by a pusher and piercing rolled to form a hollow tube, the roll speed is adjusted so that the coefficient α shown by the following formula is in the range of 1.1 to 1.3. A method for preventing biting in a press roll piercer, characterized by controlling to change one or both of the pusher speed and the pusher speed. α=Vr/(λ・Vp) Where, Vr: Roll speed Vp: Square cross section billet pushing speed (pusher speed) λ: Stretching of material 2, the circular path formed by a pair of rolls having a semicircular caliber A plug supported by a bar is positioned at the center to form a hollow circular path, and a billet with a square cross section is pushed into the hollow circular path in the longitudinal direction of the billet by a pusher to form a hollow tube by piercing and rolling.Press roll piercing rolling. A method for preventing bite in a press roll piercer, characterized in that the process uses, as a starting material, a material whose cross-sectional width L of a square cross-section billet gradually decreases within a range of 0.80 to 0.95 L per meter in the axial direction of the billet.