A method for controlling the butt in the hydrostatic extrusion process

Abstract

The present invention discloses a method for controlling the butt in the hydrostatic extrusion process. First, according to the principle of constant volume, a volume equation for the billet, the hydraulic medium, and the extrusion rod in the hydrostatic extrusion is established. Secondly, according to the characteristics of hydrostatic extrusion and the compression characteristics of the hydraulic medium, a volume equation for the change of the volume of the hydraulic medium with pressure is established. Finally, the equations are jointly solved, and after mathematical operations and transformations, a control equation for the butt length is obtained. According to the obtained control equation, the present invention can not only monitor and control the butt length, but also obtain the butt length through the hydraulic medium pressure and the position of the extrusion rod after substituting the relevant process conditions and parameters, realizing the implementation monitoring and effective control of the butt length, and solving the common industry problem that it is difficult to monitor and control the butt in hydrostatic extrusion.

Description

Technical Field

[0001] The present invention belongs to the field of special equipment, and particularly relates to a method for monitoring and controlling the residue during metal hydrostatic extrusion production. Background Art

[0002] Metal hydrostatic extrusion is commonly used in the extrusion production of high-strength and tough or difficult-to-deform alloys. Its working principle is that the extrusion rod pressurizes the hydraulic medium pre-filled in the extrusion cylinder, and the pressure is transmitted to the ingot blank in the extrusion cylinder through the hydraulic medium. One end of the ingot blank is inserted into the sizing zone of the die, and the other parts are immersed in the hydraulic medium. The pressurized hydraulic medium forces the metal ingot blank to deform and form through the die. During hydrostatic extrusion, the pressure in the extrusion cylinder is extremely high, reaching the GPa level, which belongs to ultra-ultra-high pressure.

[0003] During the hydrostatic extrusion process, monitoring and controlling the residue is a common problem in the industry. Due to the extremely high pressure of hydrostatic extrusion, excessive control of the residue will lead to a large waste of the ingot blank or the length of the produced bar not meeting the standard; insufficient control of the residue will cause the sudden release of the ultra-high pressure liquid medium pressure in the extrusion cylinder, and the extruded product will be ejected, resulting in die damage, product damage, and a great safety risk when the bar flies out. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for monitoring and controlling the residue during hydrostatic extrusion to solve the problems that in the prior art, the residue is often controlled excessively or insufficiently, resulting in die damage, product damage, and the bar flying out.

[0005] To achieve the above purpose, the present invention provides a method for monitoring and controlling the residue during metal hydrostatic extrusion production. First, according to the principle of constant volume, a volume equation of the ingot blank, the hydraulic medium, and the extrusion rod in hydrostatic extrusion is established; secondly, according to the characteristics of hydrostatic extrusion and the compression characteristics of the hydraulic medium, a volume equation of the hydraulic medium volume changing with pressure is established. Finally, the equations are jointly solved, and after mathematical operations and transformations, the control equation of the residue length L d is obtained. According to the obtained control equation, not only can the residue length be monitored and controlled, but also after substituting the relevant process conditions and parameters, the residue length L g can be obtained through the hydraulic medium pressure P and the extrusion rod position L d , that is:

[0006] The real-time length of the residue during hydrostatic extrusion is obtained;

[0007] According to the target residue length and the pressure of the hydraulic medium during the extrusion process, the stroke of the extrusion rod is obtained, and the distance from the extrusion rod to the inner end face of the die at the stop point when the extrusion ends is determined;

[0008] According to the stop point at the end of the extrusion, the position of the extrusion rod is controlled to achieve the control of the residue during the hydrostatic extrusion process.

[0009] Furthermore, the relationship among the real-time length of the residue, the pressure of the hydraulic medium during the extrusion process, and the stroke of the extrusion rod includes:

[0010]

[0011] In the formula, L d is the real-time length of the residue; L d0 is the length of the residual pressure in the initial state; P is the real-time pressure of the hydraulic medium (3); S is the real-time stroke of the extrusion rod (1); V j0 is the initial volume of the hydraulic medium (3); P e is the highest pressure corresponding to the compression ratio; u is the compression ratio of the hydraulic medium when the pressure is P e ; D 0 is the diameter of the ingot blank (4); D 1 is the inner diameter of the extrusion cylinder (5);

[0012] Furthermore, at the end of extrusion, S = L g0 - L g1 ;

[0013] wherein, L g0 is the distance from the extrusion rod (1) to the inner end face of the die in the initial state, and L g1 is the distance from the extrusion rod (1) to the inner end face of the die at the end of extrusion.

[0014] Furthermore, the calculation method of the said L g0 includes:

[0015]

[0016] Furthermore, when castor oil is used as the hydraulic medium, P e is 2000 MPa; u = 30%.

[0017] Furthermore, the method for controlling the residue includes sending a stop command to the device to stop the extrusion rod at a distance L g1 from the inner end face of the extrusion die.

[0018] The present invention provides a device for implementing the above hydrostatic extrusion method, including an extrusion rod nested at one end inside the extrusion cylinder; an extrusion die is nested at the other end inside the extrusion cylinder and is fixed on the die cushion together with the extrusion cylinder.

[0019] Furthermore, a first seal is provided between the extrusion rod and the extrusion cylinder; a second seal is provided between the extrusion die and the extrusion cylinder.

[0020] Furthermore, the extrusion cylinder is a hollow tubular structure.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] Taking the stroke of the extrusion rod, the pressure of the hydraulic medium, and the position of the extrusion rod as independent variables, according to the characteristics of hydrostatic extrusion, the present invention establishes a control equation for the length of the hydrostatic extrusion remnant, thereby dynamically obtaining the length of the extrusion remnant and realizing the effective monitoring and control of the length of the hydrostatic extrusion remnant.

[0023] The present invention establishes a dynamic control equation for the length of the hydrostatic extrusion remnant, thereby obtaining in real time the length of the extrusion remnant during the entire process of hydrostatic extrusion, realizing the implementation monitoring and effective control of the remnant length, solving the common industry problem that it is difficult to monitor and control the hydrostatic extrusion remnant, avoiding a large amount of waste of ingots caused by excessive remnant control, or the length of the produced bar stock not meeting the standards, as well as the problem that the remnant control amount is insufficient, resulting in die damage, product damage, or a great safety risk caused by the bar stock flying out. Brief Description of the Drawings

[0024] Figure 1 is a schematic diagram of the initial state of the monitoring and control method of the method of the present invention;

[0025] Figure 2 is a schematic diagram of the state during the extrusion process of the method of the present invention;

[0026] Wherein: 1. Extrusion rod; 2. First seal; 3. Hydraulic medium; 4. Ingot blank; 5. Extrusion cylinder; 6. Extrusion die; 7. Second seal; 8. Die cushion. Detailed Embodiments

[0027] The following further illustrates the present invention with specific embodiments, but does not limit the present invention in any way.

[0028] As Figures 1-2 shown, the hydrostatic extrusion remnant monitoring and control method of this embodiment at least includes an extrusion rod 1, a first seal 2 with ultra-high pressure on the extrusion rod side, a hydraulic medium 3, an ingot blank 4, an extrusion cylinder 5, an extrusion die 6, a second seal 7 with ultra-high pressure on the extrusion die side, and a die cushion 8.

[0029] Among them, one end of the extrusion rod 1 is located inside the hollow tubular extrusion cylinder 5 and is nested therein. A first seal 2 is provided between the extrusion rod 1 and the extrusion cylinder 5 to ensure that the hydraulic medium 3 inside the extrusion cylinder 5 will not leak from the gap between the extrusion rod 5 and the extrusion cylinder 5 during ultra-high pressure application. The extrusion die 6 is nested at the other end inside the extrusion cylinder 5 and is fixed to the die pad 8 together with the extrusion cylinder 5; a second seal 7 is provided between the extrusion die 6 and the extrusion cylinder 5 to ensure that the hydraulic medium 3 inside the extrusion cylinder 5 will not leak from the gap between the extrusion dies 6. The outlet of the extrusion die 6 is flush with the outer side of the extrusion cylinder 5 and is close to the die pad 8 to ensure that the die pad 8 supports the extrusion die 6 and the extrusion cylinder 5. During operation, the billet 4 to be hydrostatically extruded is placed inside the extrusion cylinder 5, and the extrusion die 6 is pre-filled to ensure that the hydraulic medium 3 will not leak from the die hole of the extrusion die.

[0030] To further illustrate this embodiment, the effective length of the billet 4, that is, the distance from the outer end face of the billet to the inner end face of the extrusion die 6, is denoted as L d , which is also the length of the butt, denoted as L in the initial state d0 , and denoted as L when the extrusion ends d1 . The hydraulic medium pressure is denoted as P, denoted as P in the initial state 0 , and denoted as P when the extrusion ends 1 . The distance from the extrusion rod 1 to the inner end face of the extrusion die 6 is denoted as L g , denoted as L in the initial state g0 , and denoted as L when the extrusion ends g1 , therefore, the real-time stroke of the extrusion rod is S = L g0 - L g .

[0031] First, according to the principle of volume invariance, an equation for the sum of the total volumes of the billet 4, the hydraulic medium 3, and the volume occupied by the forward movement of the extrusion rod 2 inside the extrusion cylinder 5 during hydrostatic extrusion is established, that is:

[0032] V 0 = V j + V d + V s (1)

[0033] In the formula:

[0034] V 0 - The volume of the billet 4 inside the extrusion cylinder + the volume of the hydraulic medium 3 + the volume of the extrusion cylinder occupied by the forward movement of the extrusion rod 1, which is a constant value;

[0035] V j - The volume of the hydraulic medium 3;

[0036] V d - The volume of the billet 4 inside the extrusion cylinder 5;

[0037] V s - The volume within the extrusion cylinder 5 occupied by the extrusion rod 1.

[0038] Secondly, according to the characteristics of hydrostatic extrusion and the compression characteristics of the hydraulic medium, establish a volume equation for the volume of the hydraulic medium 3 varying with pressure P, that is

[0039]

[0040] In the formula:

[0041] V j0 - The initial volume of the hydraulic medium 3;

[0042] P - The real-time pressure of the liquid medium, which varies with the extrusion process and is a variable;

[0043] P e - The highest pressure corresponding to the compression ratio, P e = 2000 MPa;

[0044] u - The compression ratio of the hydraulic medium when the pressure is P e , u = 30%.

[0045] The liquid medium for hydrostatic extrusion in the present invention is castor oil, and the relationship between the compression ratio and pressure of the above castor oil is its basic physical property.

[0046] Then, according to the deformation characteristics of the ingot blank, establish an equation for the relationship between the volume of the ingot blank 4 and the residue length L within the extrusion cylinder d That is

[0047]

[0048] In the formula:

[0049] D 0 - The diameter of the ingot blank 4;

[0050] L d _ The real-time length of the ingot blank 4 during extrusion within the extrusion cylinder 5, which is also the residue length.

[0051] According to the effective displacement of the extrusion rod 1, establish an equation for the relationship between the volume occupied by the extrusion rod 1 within the extrusion cylinder 5 and the displacement, that is

[0052]

[0053] In the formula:

[0054] S - The extrusion rod stroke, S = L g0 - L g , L g0 is the distance from the extrusion rod to the inner end face of the mold in the initial state, L gis the real-time distance from the extrusion rod to the inner end face of the die during the extrusion process.

[0055] According to the above equation, in the initial state,

[0056] The volume of the hydraulic medium:

[0057] V j = V j0 (5)

[0058] V j0 is the volume of the hydraulic medium 3 pre-injected into the extrusion cylinder, which is a known fixed quantity.

[0059] The volume of the ingot blank 4 in the extrusion cylinder 5:

[0060]

[0061] In the initial state, the stroke S of the extrusion rod 0 = 0, so

[0062]

[0063] Combining equations (1), (5) to (7) gives:

[0064]

[0065] According to the principle of constant volume, combining the above equations (1) to (8) gives:

[0066]

[0067] After mathematical operations and transformations on equation (9), the length of the butt, that is, the remaining length L of the ingot blank, d has the following relationship with the stroke S of the extrusion rod and the pressure P of the hydraulic medium:

[0068]

[0069] Thus, the control equation for the length of the butt in hydrostatic extrusion is obtained, where L d is the length of the ingot blank in the extrusion cylinder, that is, the length of the butt, P is the real-time pressure of the hydraulic medium in the hydrostatic extrusion cylinder, and S is the real-time stroke of the extrusion rod.

[0070] During the extrusion process, the length of the butt L d is the expression of equation (10).

[0071] At the end of the extrusion, at this time S = L g0 -L g1 , P = P 1 , substituting into equation (10) gives:

[0072] In the formula, Ld1 It is the length of the ingot in the extrusion barrel at the end of extrusion, that is, the remaining length.

[0073] Combining equations (10) and (11) can effectively control the hydrostatic extrusion pressure surplus, as follows:

[0074] In the first step, according to formula (10), the residual length L during hydrostatic extrusion can be dynamically obtained: d Real-time data;

[0075] The second step is to calculate the required target residual length L. d1 and the pressure P of the hydraulic medium 3 during the extrusion process, according to formula (11), the stroke value of the extrusion rod 1 is obtained, thereby determining the distance L from the extrusion rod to the inner end surface of the mold at the end of the extrusion stop point g1 ;

[0076] The third step is to stop the extrusion at the end point L. g1 To control the position of the extrusion rod 1, thereby achieving effective control of the hydrostatic extrusion pressure surplus.

[0077] Example 1

[0078] The following is a further explanation of the residual pressure monitoring and control of hydrostatic extrusion of tungsten alloy:

[0079] The extrusion conditions are as follows: the diameter of the tungsten alloy ingot is 100mm, the effective length is 400mm, the inner diameter of the extrusion barrel of the hydraulic extrusion equipment is 130mm, the diameter of the sizing belt of the extrusion die is 60mm, and the target residual length is 80mm. In the extrusion preparation stage, after the ingot is loaded, 4L of hydraulic medium is filled into the extrusion barrel. At the end of the extrusion, the pressure sensor of the hydrostatic extrusion equipment measures P1=1600MPa.

[0080] The parameters corresponding to the above extrusion conditions in the patent of this invention are as follows:

[0081] The diameter D of the ingot 4 0 =100mm, ingot length L d0 =400mm, extrusion cylinder inner diameter D 1 =130mm.

[0082] Initial volume V of hydraulic medium 3 j0 =4L,

[0083] Initial volume of ingot 4 Substituting the above parameters into formula (6) yields:

[0084]

[0085] Therefore, according to formula (1) and formula (7), we have:

[0086] V 0= V j + V d + V s = 7.14 L (13)

[0087] The initial distance from the extrusion rod 1 to the inner end face of the extrusion die 6 is:

[0088]

[0089] Substitute the above working condition data into Equation (10) to obtain the control equation for the residue length in tungsten alloy hydrostatic extrusion:

[0090]

[0091] The relationship between the extrusion residue length L d and the hydraulic medium pressure P and the extrusion rod stroke S is obtained from Equation (15), so that the monitoring and control of the residue length can be implemented.

[0092] The following further explains how to monitor the residue length. According to the requirement of the residue length of 80 mm in the working condition description, the pressure of the medium 3 in tungsten alloy hydrostatic extrusion forming is 1600 MPa. Substitute L d = 80 mm, P 1 = 1600 MPa into Equation (11) to get:

[0093]

[0094] Solve Equation (16) to obtain that the stroke S of the extrusion rod 1 = 261.712 mm. From this, it can be obtained that:

[0095] L g1 = 276.288 mm (17)

[0096] The instruction corresponding to the hydrostatic extrusion equipment is that when the pressure of the hydrostatic extrusion hydraulic medium 3 is 1600 MPa, the extrusion rod 1 stops at a distance of 276.288 mm from the inner end face of the extrusion die 6, and the obtained extrusion residue length is 80 mm.

[0097] In summary, the process of realizing the monitoring and control of the residue in tungsten alloy hydrostatic extrusion is as follows:

[0098] The first step is to substitute the working condition parameters into the control equation (10) according to the working conditions to establish the control equation for the residue in hydrostatic extrusion;

[0099] The second step: According to the established control equation, monitor and control the residue length through the pressure of the hydraulic medium 3 and the position of the extrusion rod 1;

[0100] Step 3: According to the required upset length in the process and the working pressure P of the hydrostatic extrusion hydraulic medium 3. For example, in this example, the required upset length is 80 mm and the hydraulic medium pressure is 1600 MPa. Substitute these values into the control equation to obtain the stroke S of the extrusion rod 1. In this example, S = 261.712 mm.

[0101] Step 4: According to the result of Step 3, determine the stop position of the extrusion rod and send a stop command to the equipment. In this example, the extrusion rod 1 stops at a distance of 276.288 mm from the inner end face of the extrusion die 6, and the obtained extrusion upset length is 80 mm.

[0102] For any person skilled in the art, without departing from the scope of the technical solution of the present invention, many possible changes and modifications can be made to the technical solution of the present invention by using the technical content disclosed above, or it can be modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for controlling the butt in the hydrostatic extrusion process, characterized in that, it includes the following steps: Obtain the real-time length of the butt in the hydrostatic extrusion process; According to the target butt length and the pressure of the hydraulic medium (3) in the extrusion process, obtain the stroke of the extrusion rod (1), and determine the distance from the extrusion rod (1) to the inner end face of the die at the stop point when extrusion ends; Control the position of the extrusion rod (1) according to the stop point when extrusion ends to achieve the control of the butt in the hydrostatic extrusion process; The relationship among the real-time length of the butt, the pressure of the hydraulic medium in the extrusion process, and the stroke of the extrusion rod includes: ， Wherein, L d is the real-time length of the residual press; L d0 is the length of the residual press in the initial state; P is the real-time pressure of the hydraulic medium (3); S is the real-time stroke of the extrusion rod (1); V j0 is the initial volume of the hydraulic medium (3); P e is the highest pressure corresponding to the compression ratio; u is the compression ratio of the hydraulic medium when the pressure is P e ; D 0 is the diameter of the ingot billet (4); D 1 is the inner diameter of the extrusion cylinder (5); At the end of extrusion, S = L g0 -L g1 ; Among them, L g0 is the distance from the extrusion rod (1) to the inner end face of the mold in the initial state, and L g1 is the distance from the extrusion rod (1) to the inner end face of the mold when extrusion ends; The said L g0 The calculation method includes: 。 2. The method for controlling the butt in the hydrostatic extrusion process according to claim 1, characterized in that, When castor oil is used as the hydraulic medium, P e is 2000 MPa; u = 30%.

3. The method for controlling the butt in the hydrostatic extrusion process according to claim 1, characterized in that, The method for controlling the residual pressure includes sending a stop command to the device to stop the extrusion rod (1) at a distance L from the inner end face of the extrusion die (6). g1 from the inner end face of the extrusion die (6).

4. A device for implementing the method for controlling the butt in the hydrostatic extrusion process according to any one of claims 1-3, characterized in that, it includes an extrusion rod (1) nested at one end inside the extrusion cylinder (5); The extrusion die (6) is nested at the other end inside the extrusion cylinder (5) and is fixed on the die pad (8) together with the extrusion cylinder (5).

5. The device according to claim 4, characterized in that, a first seal (2) is provided between the extrusion rod (1) and the extrusion cylinder (5); a second seal (7) is provided between the extrusion die (6) and the extrusion cylinder (5).

6. The device according to claim 4, characterized in that, the extrusion cylinder (5) is a hollow tubular structure.

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