Some methods of cold-drawing steel tubes
To overcome the shortcomings of conventional cold-drawing methods, the following methods of cold-drawing steel tubes have been continuously developed:
(1) Cold-drawing steel tubes with conical mandrels, which have a smaller pull rod force Pc than general short mandrels.
(2) Semi-continuous and continuous cold-drawing steel tubes. Various linear cold-drawing steel tube machines work intermittently. After drawing a tube, they need to wait for the trolley to return before they can draw the next tube. Therefore, semi-continuous and continuous cold-drawing steel tubes have been developed. There are two forms of semi-continuous cold-drawing steel tubes. One is to use a double-moving cold-drawing steel tube trolley, which is fixed on the motion chain and runs along a guide rail with a certain shape. After the upper cold-drawing steel tube trolley draws out the previous steel tube, the lower cold-drawing steel tube trolley arrives in front of the center frame and clamps the next steel tube for drawing. The other is a semi-continuous cold-drawing steel tube machine that moves the double cold-drawing steel tube mold during drawing. Continuous cold-drawing steel tube machines include crawler type and double trolley reciprocating type. The crawler-type cold drawn steel tube machine is composed of several frames with cold drawn steel tube dies at the front end. Chains are installed on both sides of the frame, and crawler links are installed on the chain shaft to compress the steel tube and force it into the cold drawn steel tube die. This continuous cold drawn steel tube machine can be used for drawing without mandrel and long mandrel, which can increase the output by 3
times compared with ordinary cold drawn steel tube machines; the problem is that it is easy to produce uneven longitudinal wall thickness when drawing without mandrel, and the resistance of using fixed molds is large, the energy consumption is high, the product surface quality is poor, and it is difficult to remove the rod. In addition, there is a continuous cold drawn steel tube with double trolley reciprocating motion, which is used for drawing without mandrel, see continuous welding, and continuous drawing of precision steel tubes.
(3) Long mandrel rolling die drawing process of round steel tube. The process of multi-roller rolling die-long mandrel drawing round steel tube is: before drawing, the steel tube head is first narrowed to match the conical transition zone of the mandrel to clamp the steel tube. Then the mandrel is inserted and the thin end of the long mandrel passes through the rolling die. During drawing, the cold drawing machine jaws hold the thin end of the mandrel make a linear motion, and pull the steel pipe and the mandrel out of the rolling die together, realizing the wall reduction and extension deformation of the steel pipe, and changing the simple cold drawing method into a combined drawing and rlling method. This method can obtain a large deformation per pass, reduce energy consumption, have a simple structure, and have good surface quality of the steel pipe; the disadvantage is that it is difficult to remove the rod.
(4) Ultrasonic vibration cold drawing of steel pipe.
(5) Roll cold drawing of steel pipe.
(6) Warm drawing of steel pipe.
(1) Cold-drawing steel tubes with conical mandrels, which have a smaller pull rod force Pc than general short mandrels.
(2) Semi-continuous and continuous cold-drawing steel tubes. Various linear cold-drawing steel tube machines work intermittently. After drawing a tube, they need to wait for the trolley to return before they can draw the next tube. Therefore, semi-continuous and continuous cold-drawing steel tubes have been developed. There are two forms of semi-continuous cold-drawing steel tubes. One is to use a double-moving cold-drawing steel tube trolley, which is fixed on the motion chain and runs along a guide rail with a certain shape. After the upper cold-drawing steel tube trolley draws out the previous steel tube, the lower cold-drawing steel tube trolley arrives in front of the center frame and clamps the next steel tube for drawing. The other is a semi-continuous cold-drawing steel tube machine that moves the double cold-drawing steel tube mold during drawing. Continuous cold-drawing steel tube machines include crawler type and double trolley reciprocating type. The crawler-type cold drawn steel tube machine is composed of several frames with cold drawn steel tube dies at the front end. Chains are installed on both sides of the frame, and crawler links are installed on the chain shaft to compress the steel tube and force it into the cold drawn steel tube die. This continuous cold drawn steel tube machine can be used for drawing without mandrel and long mandrel, which can increase the output by 3
times compared with ordinary cold drawn steel tube machines; the problem is that it is easy to produce uneven longitudinal wall thickness when drawing without mandrel, and the resistance of using fixed molds is large, the energy consumption is high, the product surface quality is poor, and it is difficult to remove the rod. In addition, there is a continuous cold drawn steel tube with double trolley reciprocating motion, which is used for drawing without mandrel, see continuous welding, and continuous drawing of precision steel tubes.
(3) Long mandrel rolling die drawing process of round steel tube. The process of multi-roller rolling die-long mandrel drawing round steel tube is: before drawing, the steel tube head is first narrowed to match the conical transition zone of the mandrel to clamp the steel tube. Then the mandrel is inserted and the thin end of the long mandrel passes through the rolling die. During drawing, the cold drawing machine jaws hold the thin end of the mandrel make a linear motion, and pull the steel pipe and the mandrel out of the rolling die together, realizing the wall reduction and extension deformation of the steel pipe, and changing the simple cold drawing method into a combined drawing and rlling method. This method can obtain a large deformation per pass, reduce energy consumption, have a simple structure, and have good surface quality of the steel pipe; the disadvantage is that it is difficult to remove the rod.
(4) Ultrasonic vibration cold drawing of steel pipe.
(5) Roll cold drawing of steel pipe.
(6) Warm drawing of steel pipe.
