RU2354468C1 - Mandrel unit of screw rolling mill - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention is intended for improving operational conditions of mandrel unit at screw rolling mill. Mandrel unit of screw rolling mill includes hollow rod with rod end and mandrel fixed to the rod. The mandrel is connected to the rod end by means of removable split terminal. The rod end is implemented as a hollow item. The outer surfaces of the rod end and mandrel are provided with circular grooves. The clamp is in the form of bushing with several lathes at each side of bushing end surfaces. The bushing itself is installed on the rod end, and reciprocal flanges are inside rod end and mandrel grooves. The reciprocal flanges are placed on the end parts of lathes. In addition, lathes are provided with screw holes for thrust screws. The circular grooves of the rod end and mandrel may be made tapered or cylindrical, respectively.

EFFECT: possibility of internal mandrel cooling, fast replacement in case of item deterioration combined with reliable mandrel fixing on rod and creation of favourable conditions for rough pipe and mandrel unit surfaces contacting during rolling.

2 cl, 1 dwg

Description

The invention relates to pipe production and relates to a method for attaching mandrels of helical rolling mills.

Known methods for connecting the mandrel with the stem of the piercing mill (Technology pipe production. V.N.Danchenko, A.P. Kolikov, B.A. Romantsev, S.V. Samusev. - M .: Intermet Engineering, 2002. - 640 p. ), in which the hollow mandrel is installed by landing on the tip of the conical profile, which is connected to the rod by threaded and welding joints. However, the tight connection of the mandrel with the tip of the rod prevents its free removal during replacement, which leads to the use of mechanical methods of separating the mandrel from the tip. In this regard, equipment downtime increases, productivity decreases and tool consumption increases.

Closest to the technical nature of the claimed device is a mandrel assembly of a rolling mill, including a hollow shaft with a fixed tip and a mandrel connected to the tip using a removable collet clamp (United States Patent, Plug changing mechanism for use in piercing mills, appl. 4,022,043 ; 05/10/1977). The disadvantage of this site is the inability to use the internal cooling of the mandrel during its operation, which leads to increased wear and tool consumption.

The objective of the invention is the possibility of internal cooling of the mandrel, its quick replacement during wear in combination with reliable fixation of the mandrel on the rod and the creation of favorable conditions for contact of the surfaces of the sleeve and the mandrel assembly during the rolling process.

The problem is achieved in that in the reference node of the screw rolling mill, including a hollow rod with a fixed tip and a mandrel connected to the tip by means of a removable color clip, the tip is hollow, the outer surfaces of the tip and mandrel have ring grooves, the clip is made in the form of a sleeve with several strips on the side of each of its end surfaces mounted on the tip with placement in the grooves of the tip and mandrel protrusions mates, made at the end s areas of bars, the straps have threaded holes for the stop screws. The ring grooves of the tip and the mandrel, it is advisable to perform respectively conical and rectangular (cylindrical) shape.

Obtaining high-quality sleeves and pipes is possible when using straighteners with a high-quality work surface, the resistance of which without internal cooling by water is no more than 10-20 passes. The use of internal cooling of the mandrels allows to increase the resistance by tens of times. Effective cooling of the mandrel is achieved by the fact that a hollow tip is installed in the rod through which coolant enters the internal cavity of the mandrel. This circumstance leads to the need to use external means of fastening the mandrel, while in the process of flashing the sleeve covers the shaft and directly contacts the fastening elements of the mandrel assembly, and therefore strict requirements are imposed on the design for the shape and quality of the outer surface, strength, heat resistance and the exclusion of the possibility resistance to movement of the sleeve relative to the rod and the mandrel. Failure to comply with these requirements may lead to disruption of the deformation process. In this regard, the design of the mandrel assembly provides for the use of a tip and a mandrel having annular grooves on the outer surfaces (preferably conical and cylindrical in cross section, respectively), as well as a clamp made in the form of a sleeve with several straps on the side of each of its end surfaces installed on the tip with the placement in the grooves of the tip and the mandrel of the protrusions of the reciprocal form, made on the end sections of the strips. This design of the fastening elements of the mandrel ensures its reliable fixation during the rolling process, without increasing the resistance to movement of the sleeve relative to the rod and the mandrel, which favorably affects the deformation process. In order to reduce the time spent on changing the spent mandrels, the grips of the collet clamp have threaded holes for the stop screws.

Together, these signs provide a solution to the problem: providing the possibility of internal cooling of the mandrel, its reliable fixation on the rod during rolling (without adversely affecting the contact conditions of the surfaces of the sleeve and the reference unit) and quick replacement during wear.

The invention is illustrated in the drawing, which shows the proposed reference site of the helical rolling mill in section. The assembly consists of a hollow mandrel 1, mounted on a protrusion 2 of the hollow tip 3, which is screwed into the socket of the rod 4 and is fixed by welding. The mandrel on the tip holds the collet clamp 5, made in the form of a sleeve with several (3 or more) strips 7, 8 on the side of each of the end surfaces of the sleeve. In each strip, holes 6 for stop screws are made. In the area of the holes 6, the strips have a smaller thickness, due to which a small gap is formed between the surfaces of the clamp 5 and the strips in this section.

The axial force of the metal on the mandrel is transmitted through the end surface "a", and the centering of the mandrel relative to the axis of rolling is carried out by a cylindrical surface "b". Spontaneous removal of the mandrel from the rod is ensured by the design features of the collet clamp. The collet clamp is double-sided. The front planks of the collet clamp have hooks - protrusions "c", the shape of which corresponds to the shape of the annular groove of the mandrel (rectangular or, otherwise, cylindrical) and which enter this groove, the rear planks are fixed in the same way in the annular conical groove of the rod tip.

The node operates as follows. When installing the mandrel on the tip 3 assembly with the rod 4, a collet clamp 5 is mounted and fixed in the position shown in the drawing. Next, three stop screws are screwed into the holes 6 of the three strips 7 from the front end face of the sleeve, while bending the strips 7. The strips can be bent due to the elastic properties of the clamp 5 and the presence of a gap between the surfaces of the strips and tip 3 in the area of the holes 6. It increased as a result the bending of the strips the gap between the ends of the strips 6 and the protrusion 2 is installed mandrel 1. At the end of the installation process, the screws are unscrewed from the strips 6.

When replacing the mandrel, the stop screws are screwed into the strips 7 of the clamp 5 and the mandrel is released, after which the mandrel is removed from the rod and a new one is installed in its place.

To remove the collet clamp from the tip 3, it is necessary to screw the stop bolts into the holes 6 of the strips 8 made on the side of the rear end of the sleeve, install the wedges into the increased gaps between the ends of the strips 8 and tip 3, and then remove the clip from the tip.

The proposed collet clamp can be made of high alloy steel grades, and the tip of the rod - from carbon or low alloy steel.

The application of the proposed site will allow the use of internal cooling of the mandrels while simplifying the removal of mandrels from the rod and increasing the reliability of fixing the mandrel on the rod during rolling without negative impact on the deformation process.

Claims (2)

1. The mandrel assembly of the screw rolling mill, including a hollow rod with a fixed tip and a mandrel connected to the tip by means of a removable collet clamp, characterized in that the tip is hollow, the outer surfaces of the tip and mandrel have annular grooves, the clamp is made in the form of a sleeve with several strips on the side of each of its end surfaces mounted on the tip with placement in the grooves of the tip and mandrel protrusions reciprocal form, made on the end sections of the strips, while the straps have threaded holes for thrust screws. 2. The mandrel assembly according to claim 1, characterized in that the annular grooves of the tip and the mandrel are made conical and cylindrical, respectively.