A method for forming a thin-walled liner with a large diameter-to-thickness ratio by spinning and additive manufacturing

Abstract

The present invention discloses a method for the integrated forming of thin-walled liner parts with a large diameter-to-thickness ratio by spinning: a tube blank is clamped on a main shaft; a heating device is installed on a longitudinal slide or a main shaft box and moves back and forth along the axial direction, so as to heat the area of ​​the tube blank to be spun to the temperature required for forming; a rotating wheel performs multiple passes of alternate back and forth diameter reduction spinning forming on the tube blank, and after each pass of diameter reduction spinning, the heating device is moved radially toward the tube blank by an optimal sensing distance, so that the temperature of the forming area of ​​the tube blank is maintained in the required temperature range; after the first end of the tube blank is spun to the required mouth size, the tube blank is turned around and clamped, so that the second end is gradually spun to form a flat bottom with a hole, and then the hole is additively manufactured to achieve bottom sealing; the rotating wheel of this method does not require a swing angle when working, which reduces the complexity of the equipment tooling and control system; it has great advantages in the overall forming of parts, is conducive to reducing the number of parts and the number of welds, thereby improving the overall quality of the liner parts and preventing rust.

Description

Technical Field

[0001] The present invention relates to the field of plastic processing and forming, and in particular to a method for integrally forming a thin-walled liner component with a large diameter-to-thickness ratio by spinning and additive manufacturing. Background Art

[0002] For parts with large diameter-to-thickness ratios, such as water heater liner, low-pressure gas cylinder, and aerospace engine and missile casings, the process often involves stamping the two ends, rolling and welding the middle into a tube, and then welding it together. Alternatively, a seamless tube blank is formed through pendulum spinning. The former method suffers from poor quality due to multiple steps and welds, while the latter method results in high tube blank costs and significant material waste due to the excessive thickness of the forming section during spinning.

[0003] However, when using large diameter-to-thickness ratio cylindrical blanks for shrink spinning, defects such as wrinkling and cracking are very likely to occur during the shrink spinning process due to the large diameter and thin wall thickness of the cylindrical blanks, making the forming process more difficult. Furthermore, large diameter cylindrical blanks are usually formed by curling and welding cold-rolled sheet, and the welds are very prone to cracking during processing, further increasing the difficulty of forming large diameter-to-thickness ratio inner shells. Summary of the Invention

[0004] The purpose of the present invention is to solve the above-mentioned problem of integrated spinning forming of a large diameter-to-thickness ratio liner with or without welds, and to provide a method for integrated spinning additive forming of a large diameter-to-thickness ratio thin-walled liner.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for the integrated forming of thin-walled liner parts with a large diameter-to-thickness ratio by spinning is disclosed. A heating device is clamped to the longitudinal slide or spindle box of a spinning machine. During spinning of the blank tube, the heating device is synchronized with the spinning wheel in the axial direction and can independently move radially toward the blank tube. The specific forming process includes the following steps:

[0007] S1. The tube is clamped to the spindle; the heating device is mounted on the longitudinal slide or the spindle box and moves back and forth in the axial direction to heat the spinning area of ​​the tube to the required forming temperature;

[0008] S2. The spinning wheel spins the tube in multiple alternating passes, and after each pass, the heating device is moved radially toward the tube to an optimal sensing distance to maintain the temperature of the tube forming area within the desired temperature range;

[0009] S3. After the first end of the tube blank is screwed and compressed to the required opening size, the tube blank is turned around and clamped, so that the second end is gradually screwed and compressed into a flat bottom with a hole, and then the hole is additively manufactured to achieve the bottom sealing.

[0010] The heating device is an induction coil, a flame spray gun or a laser heater;

[0011] When induction heating is performed using an induction coil, the induction coil is installed on one side of the spindle box and is individually controlled by a guide rail-slider device, and is driven by a motor to move closer to or away from the barrel in the vertical direction.

[0012] When a flame spray gun is used for heating, a single-head or multi-head flame spray gun can be used according to the required temperature for heating the tube blank. The flame spray gun is installed on one side of the longitudinal slide of the machine tool and moves axially with the longitudinal slide of the machine tool and approaches the tube blank, or it can be installed separately on one side of the spindle box and controlled separately by a guide rail-slider device.

[0013] When a laser heater is used for heating, the laser head of the laser heater is installed on one side of the longitudinal slide of the machine tool and moves axially with the longitudinal slide of the machine tool and approaches the tube blank, or is installed separately on one side of the spindle box and is controlled separately by a guide rail-slider device.

[0014] The axial position of the heating device is located outside the rotating wheel, that is, located in the area on one side of the end of the tube blank to be formed.

[0015] During each spinning process, the distance the heating device moves toward the tube blank should maintain the required temperature range of the material in the area to be formed in the tube blank.

[0016] Additive manufacturing includes any one of arc additive manufacturing, electron beam fuse manufacturing, and laser additive manufacturing.

[0017] Single-wheel spinning or double-wheel spinning is used in the diameter reduction spinning process.

[0018] Compared with the prior art, the present invention has the following advantages and effects:

[0019] (1) It can avoid the stamping and welding of multiple parts, which is beneficial to reducing welds and thus improving the overall strength and appearance quality of parts.

[0020] (2) Heating equipment such as flame spray guns, induction coils, and laser heaters are installed on the longitudinal slide of the machine tool and can be moved in the vertical direction, which realizes stable heating when the diameter of the tube billet changes significantly during the forming process. It overcomes the difficulty of separate coordinated control of the heating device and the forming tool and the limitation that the induction coil is only suitable for heating tube billets with constant diameter, and is conducive to the realization of automated control of hot shrink spinning.

[0021] (3) When using a flame spray gun or laser for heating, the heating device moves synchronously with the rotary wheel in each pass; when using induction heating, the radial position of the heating device can be adjusted in each pass according to parameters such as the spindle speed, the rotary wheel feed speed, and the diameter reduction amount of the previous pass to obtain the optimal distance between the heating device and the part to be formed, thereby more accurately controlling the forming temperature of the tube blank.

[0022] (4) The spinning wheel does not need to swing during multi-pass spinning, which reduces the complexity of the equipment tooling and control system and avoids material waste caused by the increase in wall thickness of the diameter reduction forming section.

[0023] (5) Combining spinning with additive manufacturing avoids longitudinal or circumferential welds and overcomes the difficulty of spinning and sealing thin-walled cylindrical parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a process flow chart of the invention's large diameter-to-thickness ratio thin-walled liner spinning additive integrated forming process.

[0025] Figure 2 This is a rough part of a thin-walled liner with a large diameter-to-thickness ratio according to an embodiment of the present invention, including: a cylinder blank 1, an induction coil 21, and two rotating wheels 31 and 32.

[0026] Figure 3 This is the inner liner target part described in the embodiment of the present invention.

[0027] Figure 4 Schematic diagram of the initial vertical position of the induction coil before double-wheel spinning of the present invention.

[0028] Figure 5 This is a front view of the radial eccentric position of the induction coil during double-wheel spinning of the present invention.

[0029] Figure 6 This is a side view of the radial eccentric position of the induction coil during double-wheel spinning of the present invention.

[0030] Figure 7 This is a front view of the concentric heating position of the induction coil to be avoided by the present invention.

[0031] Figure 8 This is a side view of the concentric heating position of the induction coil to be avoided by the present invention.

[0032] Figure 9 This is the process of arc material addition according to the present invention.

[0033] Figure 10 This is a schematic diagram of the initial position of the flame spray gun before single-wheel spinning in the present invention.

[0034] Figure 11 This is a front view of the radial position of the flame spray gun during single-wheel spinning of the present invention. DETAILED DESCRIPTION

[0035] The present invention is described in further detail below with reference to specific embodiments.

[0036] Example

[0037] The outer diameter of the cylindrical part with large diameter-to-thickness ratio is 220mm, the wall thickness is 1.4mm, and the diameter-to-thickness ratio is greater than 150 (see Figure 2 ), made of SPCC cold rolled steel sheets. Figure 3 As shown, the narrowest diameter of the closing end is 76mm. The other end is flattened by spinning through a reduced diameter, and then the bottom is sealed by additive manufacturing. Figure 1 The method of the present invention is used for heat shrinkage and spinning.

[0038] This embodiment adopts double-wheel spinning. Before processing, a single-turn induction coil with a diameter of 240mm is installed on the side of the spindle box. The servo motor drives the induction coil in the vertical direction and axial direction. In this embodiment, the induction coil 21 is placed on the tube blank 1 between the two rollers 31 and 32. The axial position of the induction coil 21 is located outside the roller 31, that is, close to the end of the tube blank to be formed. Figure 2 .

[0039] The spinning steps are as follows:

[0040] (1) Clamp the tube blank 1 to the main shaft, and arrange the induction coil 21 concentrically with the tube blank 1, as shown in FIG. Figure 4 shown.

[0041] (2) Start the main shaft and rotate it at a low speed of 100 r / min. Move the induction coil 21 back and forth with the longitudinal slide at a speed of 50 mm / s until the part of the tube to be formed is heated to 600±10°C.

[0042] (3) Increase the spindle speed to 350r / min, perform multiple-pass alternating back-and-forth spinning with a pass reduction of 3mm and a spinner feed ratio of 2.8mm / r. After each pass, press the induction coil 21 Figure 5 、 6 The vertical direction is moved 2.5 mm to control the temperature of the part to be formed within the range of 500-600° C. until the spinning forming of one end of the tube blank 1 is completed.

[0043] If the induction coil 21 is always kept concentric with the tube blank 1 during the multi-pass spinning process, Figure 7 、 8 The improperly heated area shown is that the temperature of the annular area at position A is higher because the induction coil is closest to position A, while the annular area at position B to be formed cannot reach the specified forming temperature in time because it is far away from the induction coil.

[0044] (4) Remove the workpiece and turn it around to clamp it on the spindle. Repeat steps (2) and (3) to shrink the other end of the tube blank and spin it to a small hole of 4±0.5mm (see Figure 9 Small hole diagram) and ensure that the bottom is flat.

[0045] (5) The small hole is sealed by arc additive manufacturing to achieve the bottom sealing of the inner liner, and the large diameter-to-thickness ratio inner liner is integrated into the molding process. Figure 9 , where 4 is an arc fuse welding gun.

[0046] If the double-rotating wheel is changed to a single-rotating wheel 3 for spinning, the induction coil 21 is replaced with a flame spray gun 22, and the flame spray gun 22 is installed on the longitudinal slide of the machine tool. The flame spray gun 22 can move axially and radially with the longitudinal slide, such as Figure 10 shown.

[0047] In this embodiment, the process parameters of multi-pass spinning are the same as those in Example 1, namely, the spindle speed is 350 r / min, the pass reduction is 3 mm, the feed ratio of the spinning wheel is 2.8 mm / r, and after each pass, the flame spray gun 22 is moved synchronously with the longitudinal slide of the machine tool and the spinning wheel in the radial direction. Figure 10 shown.

[0048] As described above, the present invention can be implemented better.

[0049] The implementation methods of the present invention are not limited to the above-mentioned embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for forming a thin-walled liner with a large diameter-to-thickness ratio by spinning and additive manufacturing, characterized in that The heating device is clamped on the spindle box of the spinning machine. When the tube blank is spun, the heating device must be synchronized with the spinning wheel in the axial direction and can move independently in the radial direction of the tube blank. The specific forming process includes the following steps: S1. The tube is clamped to the spindle; the heating device is mounted on the spindle box and moves back and forth axially to heat the spinning area of ​​the tube to the required forming temperature; S2. The spinning wheel spins the tube in multiple alternating passes, and after each pass, the heating device is moved radially toward the tube to an optimal sensing distance to maintain the temperature of the tube forming area within the desired temperature range. S3. After the first end of the tube is compressed to the desired opening size, the tube is turned and clamped, so that the second end is gradually compressed to form a flat bottom with a hole, and then the hole is additively manufactured to achieve the bottom seal; The heating device is an induction coil; The induction coil is mounted on one side of the spindle box and is independently controlled by a guide rail-slider device. The induction coil is driven by a motor to move vertically toward or away from the barrel. The induction coil is sleeved on the barrel. The axial position of the heating device is located outside the rotating wheel, that is, located on the end side of the tube blank to be formed; Double-wheel spinning is adopted in the diameter-reducing spinning process.

2. The method for integrally forming a thin-walled liner with a large diameter-to-thickness ratio by spinning and additive manufacturing according to claim 1, characterized in that: During each spinning process, the distance the heating device moves toward the tube blank should maintain the required temperature range of the material in the area to be formed of the tube blank.

3. The method for integrally forming a thin-walled liner with a large diameter-to-thickness ratio by spinning and additive manufacturing according to claim 1, characterized in that: The additive manufacturing includes any one of arc additive manufacturing, electron beam fusing, and laser additive manufacturing.

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