Near-isothermal hot spin forming method and heat complementing method for metal workpiece

Abstract

A near-isothermal hot spin forming method and a heat complementing method for a metal workpiece are provided. The forming method comprises: transferring and clamping a blank heated to a spin preheating temperature on a workbench, wherein the blank is located in an effective heat complementing zone provided by a heat complementing system; measuring a temperature of the blank to judge whether the temperature of the blank satisfies a pre-spinning temperature to determine whether the blank waits for temperature complement in the heat complementing system; and completing the near-isothermal hot spinning process in the heat complementing system according to the preset spinning program. During the spinning process, the heat complementing system continuously supplements the temperature of the blank and monitors the spinning temperature in real time to ensure that the fluctuation range of the spinning temperature does not exceed ±20° C. from the beginning to the end of the spinning deformation.

What is claimed is: 
     
         1 . A near-isothermal hot spin forming method for a metal workpiece, comprising steps of:
 heating a blank to a spin preheating temperature;   transferring and clamping the heated blank on a workbench rotating with a main shaft of a spinning device, wherein a heat complementing system is mounted on a periphery of the workbench, and the blank is located in an effective heat complementing zone provided by the heat complementing system;   measuring a blank temperature of the blank after clamping and fixing, and judging whether the blank temperature T blank  meets a pre-spinning temperature T b spinning  of the blank required by a near-isothermal hot spinning process; if T blank ≥T b spinning , starting the spinning device to perform spinning; and if T blank <T b spinning , heating and temperature complementing the blank by the heat complementing system until T blank ≥T b spinning  is satisfied, and then starting the spinning device to perform spinning; and   applying the near-isothermal hot spinning process in the spinning device to spinning form the blank; wherein during the near isothermal hot spinning process, the blank is actively heated and temperature complemented by the heat complementing system, and a spinning temperature is monitored in a spinning deformation zone of the blank in real time to ensure that a fluctuation range of the spinning temperature does not exceed ±20° C. from the beginning of a spinning deformation to the end.   
     
     
         2 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 1 , wherein a time taken to complete the transferring and clamping of the heated blank on the workbench of the spinning device is taken as a transferring time which is required not to exceed 90 s. 
     
     
         3 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 1 , wherein the spinning device comprises a machine body, a heat complementing system and a spinning roller system;
 a workbench is mounted on a main shaft of the machine body;   the spinning roller system comprises a spinning roller assembly;   the heat complementing system comprises a furnace body and a temperature control system;   the temperature control system comprises a furnace body temperature measurement module, a control module and a heating module;   the heating module comprises a plurality of heating elements;   a furnace cavity is formed in the furnace body, wherein the heating element is arranged on an inner wall of the furnace cavity for forming an effective temperature complementing zone in the furnace cavity;   a spinning roller movement groove is provided on the furnace body, and the spinning roller assembly passes through the spinning roller movement groove for ensuring that the spinning roller assembly can move freely in a radial direction and a axial direction of the blank;   the furnace body temperature measurement module is configured for detecting a temperature of the effective temperature complementing zone; and   the furnace body temperature measurement module and the heating module are both electrically connected to the control module.   
     
     
         4 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 3 , wherein the spinning roller assembly comprises an inner spinning roller and an outer spinning roller;
 during a operation of the spinning roller assembly, all structures of the inner spinning roller and part of structures of the outer spinning roller are located in the effective temperature complementing zone of the heat complementing system;   the inner spinning roller is located on an inner side of the blank and can abut against an inner wall of the blank of the workpiece;   the outer spinning roller is located on an outer side of the blank and can abut against an outer wall of the blank of the workpiece; and   the inner spinning roller and the outer spinning roller pass through the spinning roller movement groove and are located in the spinning roller movement groove, ensuring that the inner spinning roller and the outer spinning roller are free to move independently in the radial direction and the axial direction along the blank.   
     
     
         5 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 3 , wherein the furnace body comprises a furnace body I and a furnace body II,
 the furnace body I and the furnace body II are provided opposite to each other;   the furnace body I and the furnace body II can be close to or away from the workbench;   the furnace body I and the furnace body II are close to each other to form the furnace cavity, so that the blank is located in the effective temperature complementing zone of the furnace cavity;   a first spinning roller movement groove is provided on the furnace body I;   a second spinning roller movement groove is provided on the furnace body II; and   the first spinning roller movement groove and the second spinning roller movement groove form the spinning roller movement groove.   
     
     
         6 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 5 , wherein the furnace body I and the furnace body II close the furnace body of the heat complementing system by approaching the workbench;
 the furnace body I and the furnace body II open the furnace body of the heat complementing system by being away from the workbench;   a time taken for the furnace body to complete the closing is controlled within 15 s; and   a time taken for the furnace body to complete the opening is controlled within 15 s.   
     
     
         7 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 1 , wherein the blank temperature T blank  is measured on the blank after clamping and fixing, and compared with the pre-spinning temperature T b spinning  required by the near-isothermal hot spinning process;
 if T blank <T b spinning , it starts and waits for the heat complementing system to heat and temperature complement the blank; the heat complementing system adjusts a heating power of a heating element to increase a temperature rising rate of the temperature complementing, actively complement and heat the blank within a specified heat complementing time of the near-isothermal hot spinning process, so that the blank temperature reaches the pre-spinning temperature, and then the spinning device is started for spinning the workpiece according to a predetermined spinning program; and   if T blank ≥T b spinning , the heat complementing system is started to temperature complement the blank; at the same time, it starts the spinning device to start spinning according to the predetermined spinning program; and the heat complementing system maintains the heating power of the heating element, so as to maintain the blank temperature within a spinning temperature range.   
     
     
         8 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 7 , wherein a temperature of the effective temperature complementing zone of the heat complementing system is not higher than the spin preheating temperature;
 if T blank <T b spinning , it starts the heat complementing system to heat and temperature complement the blank; and   the heat complementing time of the heat complementing system does not exceed 5 min.   
     
     
         9 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 1 , wherein the spinning device is further provided with a blank temperature measurement module for detecting the blank temperature of the blank located in an effective temperature complementing zone to obtain the blank temperature or the spinning temperature; and
 the blank temperature measurement module is externally provided on the heat complementing system or a machine body of the spinning device.   
     
     
         10 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 1 , wherein during the near-isothermal spinning process, the blank is heated and temperature complemented by the heat complementing system, so as to ensure that the fluctuation range of the spinning temperature does not exceed ±10° C. from the beginning of the spinning deformation to the end. 
     
     
         11 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 1 , wherein the spinning temperature is 900-1150° C. for the blank of high temperature alloy materials. 
     
     
         12 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 1 , wherein the spinning temperature is 700-900° C. for the blank of titanium alloy materials. 
     
     
         13 . The near-isothermal hot spin forming method for the metal workpiece according to  claim 1 , wherein during the spin forming of the blank by the near-isothermal hot spinning process,
 a rotation speed of the blank is 50-300 r/min;   an feed ratio of a spinning roller is 0.1-3 mm/r;   a radius of a round corner of the spinning roller is 0.3 t-2.5 t, wherein t is a wall thickness of the blank; and   a reduction rate of each pass does not exceed a limit reduction rate of a blank material, the reduction rate of the each pass being 10-40%.   
     
     
         14 . A metal workpiece, wherein the metal workpiece is prepared by the near-isothermal hot spin forming method for the metal workpiece according to  claim 1 . 
     
     
         15 . The metal workpiece according to  claim 14 , wherein the metal workpiece is one of a rectangular workpiece, a flange workpiece, an I-shaped workpiece, an L-shaped workpiece, a long cylindrical workpiece, a cone part, and an irregular part. 
     
     
         16 . A heat complementing method for the near-isothermal hot spin forming method according to  claim 1 , wherein the heat complementing method comprises steps below:
 after the heated blank is transferred and clamped on the workbench rotating with the main shaft of the spinning device, the blank is located in an effective temperature complementing zone of the heat complementing system, and the heat complementing system is configured for heating and temperature complementing the blank; by setting a target complement temperature and a heating rate of the heat complementing system, the blank temperature T blank  reaches the pre-spinning temperature T b spinning  required by the near-isothermal hot spinning process, and a calculation formula of the pre-spinning temperature T b spinning  is as follows:   
       
         
           
             
               
                 T 
                 
                   b 
                   ⁢ 
                      
                   spinning 
                 
               
               = 
               
                 
                   T 
                   spinning 
                 
                 - 
                 
                   Δ 
                   ⁢ 
                   T 
                 
               
             
           
         
         where T spinning  is the spinning temperature measured in the spinning deformation zone during the spinning process of the workpiece; ΔT is a temperature rise caused by the heat generated by the spinning deformation; 
         after the blank temperature T blank  reaches the pre-spinning temperature T b spinning  required by the near-isothermal hot spinning process, the spinning device is started to perform spinning according to a pre-spinning program; and at the same time, the heating complementing system is started to heat and temperature complement the blank so that the spinning temperature is controlled within a range required by the near-isothermal hot spinning process, with the fluctuation range not exceeding ±20° C. from the beginning to the end of the spinning deformation. 
       
     
     
         17 . The heat complementing method according to  claim 16 , wherein a calculation formula of ΔT is as follows: 
       
         
           
             
               
                 Δ 
                 ⁢ 
                 T 
               
               = 
               
                 Q 
                 
                   m 
                   ⁢ 
                   C 
                 
               
             
           
         
         where Q is a heat generated by plastic deformation; m is a mass of the blank; and C is a specific heat capacity of a blank material. 
       
     
     
         18 . The heat complementing method according to  claim 17 , wherein a calculation formula of the heat Q generated by the plastic deformation is as follows: 
       
         
           
             
               Q 
               = 
               
                 θ 
                 * 
                 
                   σ 
                   ¯ 
                 
                 * 
                 
                   ε 
                   ˙ 
                 
               
             
           
         
         where θ is a deformation thermal effect coefficient;  σ  is an equivalent stress at a deformation temperature; and {dot over (ε)} is an equivalent strain rate of the spinning deformation.