A low melting point alloy filling and straightening method

Abstract

The present invention provides a low-melting-point alloy filling and straightening method, comprising the following steps: S10, preparation step: filling the low-melting-point alloy into a molten pool and heating it to a molten state; S20, pre-treatment step: passing the lead screw to be straightened through a feed port, a molten pool, and a discharge port in sequence, and a cooling device is provided at the discharge port to cool the low-melting-point alloy attached to the lead screw to be straightened, so that the lead screw to be straightened is in a smooth state; S30, straightening step: the lead screw to be straightened enters the straightening device through the discharge port to straighten the lead screw to be straightened. By inserting the lead screw into a molten pool filled with liquid low-melting-point alloy, the low-melting-point alloy solidifies into the lead screw spiral groove, the lead screw becomes a smooth rod, and then the straightening method of the smooth rod is used to straighten the lead screw. This straightening method is simpler, easier to operate and more effective than the existing method, and will not cause any damage to the lead screw spiral groove.

Description

Technical Field

[0001] The invention relates to the technical field of lead screw straightening, and in particular to a low melting point alloy filling and straightening method. Background Art

[0002] CNC machine tools are indispensable basic equipment in industrial production. The accuracy and stability of CNC machine tools mainly depend on the transmission elements. The lead screw is the most commonly used transmission element in CNC machine tools. Its main function is to convert rotational motion into linear motion, or to convert torque into axial repetitive force. Since the lead screw is a slender rod-shaped part and is a flexible part, it has poor rigidity and is very easy to deform. There will be processing errors such as straightness and cylindricity. Therefore, after the lead screw is processed, it is usually necessary to straighten the lead screw. The front section of the lead screw is a smooth bar. After the smooth bar is straightened, it is necessary to dig a spiral groove on the outer periphery of the smooth bar and then straighten the lead screw.

[0003] There are many methods for straightening the smooth rod in the prior art, and most of them use an inclined roller device to straighten it. In the process of digging the spiral groove on the smooth rod, the lead screw is prone to bending. Therefore, the lead screw needs to be straightened again after digging the spiral groove. If the straightening method of the smooth rod is directly transferred to the lead screw straightening, it is easy to damage the spiral groove. In the prior art, the lead screw straightening has always been manually inspected, and then the lead screw is straightened by a press using a two-point support and center-down pressure method. The straightening effect depends entirely on the worker's operating level and experience. Therefore, how to effectively straighten the lead screw and avoid damage to the spiral groove has become the main difficulty in lead screw straightening. Summary of the invention

[0004] The present invention aims to propose a method for straightening a lead screw by utilizing the liquid-to-solid state transformation of a low-melting-point alloy, thereby solving the above-mentioned problems existing in the prior art.

[0005] To achieve the above-mentioned purpose, the present invention provides a low-melting-point alloy filling and straightening method, comprising the following steps: S10, a preparation step: filling the low-melting-point alloy into a molten pool and heating it to a molten state; S20, a pre-treatment step: passing the lead screw to be straightened through a feed port, a molten pool, and a discharge port in sequence, wherein a cooling device is provided at the discharge port to cool the low-melting-point alloy attached to the lead screw to be straightened so that the lead screw to be straightened is in a smooth state; S30, a straightening step: the lead screw to be straightened passes through the discharge port and enters the straightening device to straighten the lead screw to be straightened.

[0006] As a further improvement of the present invention, the straightening step also includes a straightening detection step S40, S40 specifically includes: S41, a first detection device is provided at the outlet of the straightening device, the first detection device is used to collect contour information of the straightened screw to determine the maximum deformation of the screw; S42, the maximum deformation is compared with a preset deformation threshold, if the maximum deformation>deformation threshold, return to the straightening step, if the maximum deformation ≤deformation threshold, enter the cleaning step.

[0007] As a further improvement of the present invention, the cleaning step S50 specifically includes: sending the straightened lead screw into a post-processing module, heating the straightened lead screw, melting and removing the low-melting-point alloy.

[0008] As a further improvement of the present invention, a cleaning detection step S60 is also included after the cleaning step. S60 specifically includes: S61. A second detection device is provided at the outlet of the post-processing module. The second detection device is used to collect contour information of the cleaned screw to determine the maximum deformation of the screw thread groove; S62. The maximum deformation is compared with a preset deformation threshold. If the maximum deformation>deformation threshold, return to the cleaning step. If the maximum deformation≤deformation threshold, the straightening is completed.

[0009] As a further improvement of the present invention, in any step from S10 to S60, the lead screw to be straightened is moved by a conveying device; wherein the conveying device drives the lead screw to be straightened to move forward under the action of the driving device.

[0010] As a further improvement of the present invention, the melting point of the low melting point alloy is below 180°C.

[0011] As a further improvement of the present invention, the low melting point alloy includes one or more of tin, lead and bismuth.

[0012] As a further improvement of the present invention, the low melting point alloy includes bismuth element.

[0013] As a further improvement of the present invention, the mass fraction of bismuth element in the low melting point alloy is 37%-70%.

[0014] As a further improvement of the present invention, when the low melting point alloy changes from liquid to solid, the low melting point alloy expands in volume or maintains a constant volume.

[0015] After adopting the technical solution of the present invention, the following technical effects can be achieved:

[0016] (1) The present invention provides a low-melting-point alloy filling and straightening method, which creatively utilizes the liquid-to-solid transformation of the low-melting-point alloy to fill the spiral groove of the lead screw. The lead screw is inserted into a molten pool filled with liquid low-melting-point alloy, and the low-melting-point alloy solidifies into the spiral groove of the lead screw, and the lead screw becomes a smooth rod. Then, the straightening method of the smooth rod is used to straighten the lead screw. Compared with the existing method, the straightening method of the present invention is simpler, easier to operate and more effective. If the lead screw is directly used as a smooth rod and straightened by an inclined roller device, the spiral groove of the lead screw will be damaged. By using the method provided by the present invention, the low-melting-point alloy is solidified into the spiral groove of the lead screw, and the straightening device is used to straighten it, which will not cause any damage to the spiral groove of the lead screw.

[0017] (2) The melting temperature of the low melting point alloy in the present invention is relatively low, and only relatively low energy consumption is required to keep the low melting point alloy in a molten state. A cooling device is provided at the outlet of the molten pool, so that when the straightening screw passes through the molten pool, the low melting point alloy solidifies when it is cold and covers the spiral groove, so that the screw becomes a smooth rod. The method and device are both simple and feasible. After the straightening is completed, the low melting point alloy can be eliminated by heating, and the low melting point alloy can be recycled, saving costs.

[0018] (3) The volume of the low-melting-point alloy selected by the present invention expands or remains unchanged when it changes from liquid to solid. Most alloys shrink when they change from liquid to solid. The shrinkage will cause cracks when they are covered in the spiral groove of the lead screw, resulting in loose connection. The alloy will fall off with a slight force, exposing the spiral groove. The volume of the low-melting-point alloy selected by the present invention expands or remains unchanged when it changes from liquid to solid. The alloy can be tightly covered in the spiral groove of the lead screw. After the low-melting-point alloy forms a solid state, it is cooled synchronously with the lead screw to be straightened. It is not easy to fall off during the cooling process, so the structure is more stable and the straightening effect is better.

[0019] (4) The low-melting-point alloy filling and straightening method provided by the present invention realizes a fully automatic process by adding a straightening detection step and a cleaning detection step, thereby avoiding errors caused by manual operation, and the entire straightening process is more accurate and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0021] Figure 1 A schematic structural diagram of a lead screw straightening device provided in Example 1 of the present invention;

[0022] Figure 2 A schematic diagram of the structure of the molten pool and post-processing module provided in Example 1 of the present invention;

[0023] Figure 3 A schematic diagram of the structure of a straightening module provided in Embodiment 1 of the present invention;

[0024] Figure 4 A flow chart of a lead screw straightening method provided in Example 2 of the present invention;

[0025] Figure 5 The lead-bismuth binary phase diagram provided in Example 2 of the present invention;

[0026] Figure 6 The tin-bismuth binary phase diagram provided in Example 2 of the present invention.

[0027] Description of reference numerals:

[0028] 100-molten pool; 110-feed port; 120-discharge port; 130-first conveying device; 200-straightening device; 210-straightening roller; 220-second conveying device; 300-post-processing module; 310-post-processing module base; 320-post-processing feed port; 330-post-processing discharge port; 340-heating device; 350-third conveying device; 400-base; 500-screw to be straightened. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Combine the following Figures 1 to 6 The technical solution provided by the present invention is described in more detail.

[0031] [Example 1]

[0032] The present invention relates to a low melting point alloy filling and straightening device, such as Figure 1-Figure 3 As shown, it includes: a base 400, a molten pool 100, a straightening device 200 and a post-processing module 300.

[0033] The susceptor 400 is provided with a molten pool 100 , a straightening device 200 and a post-processing module 300 .

[0034] The molten pool 100 includes a heating element that can heat the molten pool body. The molten pool 100 is provided with a feed port 110 and a discharge port 120. In this embodiment, the feed port 110 and the discharge port 120 are respectively arranged in the horizontal direction on both sides of the molten pool 100. A cooling device is arranged at one end of the outer side of the molten pool 100 near the discharge port 120. The lead screw 500 to be straightened enters from the feed port 110, passes through the molten pool 100, passes through the discharge port 120, and reaches the position of the cooling device to cool the low melting point alloy.

[0035] Further, such as Figure 2 As shown, the feed port 110 and the discharge port 120 are both provided with a first conveying device 130, which is provided on the base 400, and its purpose is to convey the lead screw 500 to be straightened from the feed port 110 to the molten pool 100 at the feed port 110, and to convey the lead screw 500 to be straightened from the molten pool 100 to the outside of the discharge port 120 at the discharge port 120. The driving device drives the first conveying device 130 to operate, so that the lead screw 500 to be straightened passes through the feed port 110 into the molten pool 100, and then is conveyed from the molten pool 100 through the discharge port 120 to the outside.

[0036] Specifically, the outer diameter of the molten pool 100 is smaller than the length of the lead screw 500 to be straightened, so as to ensure that the lead screw 500 to be straightened can pass through the discharge port 120 after entering the molten pool 100 from the feed port 110. After the lead screw 500 to be straightened passes through, the spiral groove is filled with low melting point alloy, so it is in a bare state.

[0037] The straightening device 200 includes at least one pair of straightening rollers 210, and the discharge port 120 is connected to the straightening rollers 210. The lead screw 500 to be straightened can pass through the discharge port 120 and the straightening rollers 210 for straightening. If the spiral groove of the lead screw 500 to be straightened is not filled and the lead screw 500 to be straightened is directly straightened by a bare rod straightening method, the spiral groove of the lead screw will be damaged, and the force will be uneven during the straightening process, affecting the straightening effect. In the present invention, the characteristics of the liquid-solid state transformation of the low-melting-point alloy are utilized to fill the spiral groove of the lead screw 500 to be straightened, prepare for the straightening step, and effectively improve the straightening effect.

[0038] Specifically, Figure 3 As shown, the straightening device 200 includes a second conveying device 220, which is a plurality of conveying rollers arranged in sequence. The lead screw 500 to be straightened is straightened by the straightening device 200 under the drive of the conveying rollers.

[0039] Specifically, the molten pool 100 is filled with a low melting point alloy, and the low melting point alloy is heated by a heating device to make the low melting point alloy in a molten state.

[0040] Furthermore, the cooling device rapidly cools and solidifies the low-melting-point alloy solution at the discharge port 120, so as to avoid the low-melting-point alloy solution from cooling too slowly and being unable to solidify in the spiral groove of the lead screw, thereby affecting the straightening treatment effect.

[0041] In this embodiment, the second conveying device 220 is composed of conveying rollers. After the lead screw 500 to be straightened forming the optical bar passes through the discharge port 120 under the drive of the second conveying device 220, it passes through the straightening roller 210. The straightening roller 210 rotates continuously under the action of the driving device, and the lead screw 500 to be straightened is straightened and driven forward.

[0042] Specifically, Figure 3 As shown, the straightening rollers 210 are arranged in two rows, the upper and lower rows. When the lead screw 500 to be straightened passes between the two rows of rollers staggered with each other, it is repeatedly bent, thereby straightening the lead screw 500. The low melting point alloy on the lead screw 500 to be straightened solidifies in the spiral groove of the lead screw, which protects the spiral groove of the lead screw and prevents the straightening rollers 210 from damaging the spiral groove of the lead screw during the rotation and extrusion of the lead screw.

[0043] In order to ensure the straightening effect, a detection device is provided at the rear end of the straightening device 200. Specifically, the detection device is an image sensor, which can perform image recognition on the straightened screw, collect information, compare the screw profile and other information, determine the straightening effect, and determine whether repeated straightening is needed until the screw meets the process requirements.

[0044] Furthermore, the low melting point alloy filling and straightening equipment in this embodiment also includes a post-processing module 300, which includes a post-processing module base 310, a post-processing feed port 320 and a post-processing discharge port 330, a heating device 340 for heating the post-processing module base 310, and a reflux pipe connected to the molten pool 100 and arranged at the bottom of the post-processing module base 310. Specifically, the post-processing feed port 320 and / or the post-processing discharge port 330 are provided with a third conveying device 350, and the third conveying device 350 drives the straightening lead screw 500 to rotate and / or move forward through a driving device. The straightened lead screw passes through the post-processing feed port 320 via the third conveying device 350 and enters the post-processing module base 310. By heating, the low melting point alloy filled in the spiral groove is melted again and falls into the molten pool 100. The post-processing module 300 processes the straightened lead screw to eliminate the low melting point alloy in the spiral groove of the lead screw, so that the lead screw can be used normally and the low melting point alloy can be reused. In this embodiment, the driving device can be a motor device or a cylinder device, and any device that can produce a driving effect can be used, including but not limited to the situations listed in this embodiment.

[0045] Furthermore, an ultrasonic vibration device is provided at the post-processing feed port 320 and / or the discharge port 120, and the molten low-melting-point alloy can be made to fall off more quickly and thoroughly through ultrasonic vibration, thereby reducing the number of post-processing times.

[0046] Furthermore, an image sensor is provided at the post-processing outlet 330, which performs image recognition on the processed lead screw, collects information, and compares information such as the lead screw profile to determine the cleaning effect, thereby determining whether further post-processing is needed until the lead screw meets the process requirements.

[0047] [Example 2]

[0048] An embodiment of the present invention provides a low-melting-point alloy filling and straightening method, which can be applied to the low-melting-point alloy filling and straightening equipment provided in the above embodiments.

[0049] like Figure 4 As shown, the low melting point alloy filling and straightening method includes:

[0050] S10, preparation step: filling the low melting point alloy into the molten pool and heating it to a molten state;

[0051] S20, pre-treatment step: passing the lead screw to be straightened through a feed port, a molten pool, and a discharge port in sequence, wherein a cooling device is provided at the discharge port to cool the low melting point alloy attached to the lead screw to be straightened, so that the lead screw to be straightened is in a smooth state;

[0052] S30, straightening step: the straightening screw passes through the discharge port and enters the straightening device to straighten the screw;

[0053] S40, straightening detection step: after the straightening screw has gone through the straightening step, it enters the straightening detection step, a detection device is provided at the outlet of the straightening device, the detection device collects the profile information of the straightened screw after the straightening step, determines the maximum deformation of the straightened screw and compares it with a preset deformation threshold, if the maximum deformation> deformation threshold, returns to the straightening step, if the maximum deformation ≤ deformation threshold, enters the cleaning step;

[0054] S50, cleaning step: After the straightening step, the straightened lead screw enters a post-processing module, where the straightened lead screw is heated to melt and remove the low melting point alloy;

[0055] S60, cleaning and inspection step: After the straightened screw passes through the cleaning step, it enters the cleaning and inspection step. A detection device is provided at the exit of the post-processing module. The detection device collects the contour information of the screw after the cleaning step, determines the maximum deformation of the screw thread groove after straightening, and compares it with the preset deformation threshold. If the maximum deformation > deformation threshold, it returns to the cleaning step. If the maximum deformation ≤ deformation threshold, the straightening is completed.

[0056] In the prior art, in order to avoid damaging the spiral groove of the lead screw, manual inspection has always been used for lead screw straightening, and then the lead screw is straightened by a press using a two-point support and center downward pressure method. The straightening effect depends entirely on the worker's operating level and experience. The present method makes full use of the liquid-solid state transformation of a low-melting-point alloy to transform the lead screw to be straightened into a state similar to a bare rod, and then straightens the lead screw to be straightened. The present method can achieve a fully automatic straightening process through the device in the above embodiment, by melting the low-melting-point alloy to fill the spiral groove of the lead screw, and then straightening the lead screw through a straightening device.

[0057] Furthermore, the melting point of the low melting point alloy is below 180°C. After melting, the alloy can solidify into the spiral groove of the screw. This temperature is much lower than the screw tempering temperature. Selecting a low melting point alloy can reduce the heating time, and the melting and solidification process will not affect the screw performance. If the heating temperature is too high, the temperature will affect the screw performance, which will in turn affect the changes in the screw material structure, resulting in poor screw performance.

[0058] Most alloys have a high melting point, and in the present invention, it is further preferred that the low melting point alloy contains bismuth. Figure 5 , Figure 6 As shown, the melting point of bismuth element itself is 273°C, and the melting point of some bismuth alloys is lower than 180°C, such as lead-bismuth alloy or tin-bismuth alloy.

[0059] Lead-bismuth alloy has a very low eutectic melting point, with a composition of 44% lead (Pb) and 56% bismuth (Bi) at the eutectic point, and a melting point of 125°C. Specifically, the melting point range is below 180°C when the bismuth content is 37%-70%.

[0060] The tin-bismuth alloy has a very low eutectic melting point, with a composition of 33% tin (Sn) and 67% bismuth (Bi) at the eutectic point, and a melting point of 139°C. Specifically, the melting point range is below 180°C when the bismuth content is 37%-70%.

[0061] It can be seen that within a certain composition range, the melting point of the alloy containing bismuth element is lower than 180°C.

[0062] Furthermore, the volume of the low-melting-point alloy expands or remains unchanged when it changes from liquid to solid. The vast majority of metal alloys shrink in volume when they change from liquid to solid. In this method, if shrinkage occurs when the alloy solidifies, the spiral groove of the lead screw cannot be fully filled, causing it to fall off. According to the existing literature "Solidification Process and Microstructure Evolution of Molten Deposition of Bismuth-Tin Alloy" by Rong Wenjuan et al. and "Application of Tin-Bismuth Alloy Molds in Trial Production of New Products" by Zhang Yangming et al., the volume of lead-bismuth alloy or tin-bismuth alloy expands slightly when it changes from liquid to solid. The slight expansion of the volume when the alloy solidifies can better fill the spiral groove of the lead screw, making the filling tighter and the bonding strength higher, and the problem of falling off will not occur during the subsequent straightening process.

[0063] Furthermore, in the cleaning step, the straightened lead screw is heated to melt the low melting point alloy, and the low melting point alloy can be reused, further reducing costs. For further cleaning, the cleaning step can be repeated multiple times.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low melting point alloy filling and straightening method, characterized in that: The following steps are involved: S10, preparation step: filling the low melting point alloy into the molten pool and heating it to a molten state; S20, pre-treatment step: passing the lead screw to be straightened through the feed inlet, the molten pool, and the discharge port in sequence, wherein a cooling device is provided at the discharge port to cool the low-melting-point alloy attached to the lead screw to be straightened, so that the lead screw to be straightened is in a smooth state; wherein the molten pool is filled with a low-melting-point alloy, and the low-melting-point alloy is heated by a heating device to make the low-melting-point alloy in a molten state; the cooling device rapidly cools and solidifies the low-melting-point alloy solution at the discharge port; the outer diameter of the molten pool is smaller than the length of the lead screw to be straightened, and after the lead screw to be straightened enters the molten pool from the feed inlet and passes through the discharge port, the spiral groove of the lead screw is filled with the low-melting-point alloy, so that the lead screw to be straightened is in a smooth state; S30, straightening step: the lead screw to be straightened passes through the discharge port and enters the straightening device to straighten the lead screw to be straightened; S40, straightening detection step: a first detection device is provided at the outlet of the straightening device, and the first detection device is used to collect the profile information of the straightened lead screw to determine the maximum deformation of the lead screw; the maximum deformation is compared with a preset deformation threshold, if the maximum deformation> deformation threshold, then return to the straightening step, if the maximum deformation ≤ deformation threshold, then enter the cleaning step; S50, cleaning step: sending the straightened lead screw into a post-processing module, heating the straightened lead screw, melting and removing the low melting point alloy; S60, cleaning detection step: a second detection device is provided at the outlet of the post-processing module, and the second detection device is used to collect the profile information of the cleaned screw to determine the maximum deformation of the screw thread groove; the maximum deformation is compared with a preset deformation threshold, if the maximum deformation>deformation threshold, return to the cleaning step, if the maximum deformation ≤deformation threshold, the straightening is completed.

2. The low melting point alloy filling and straightening method according to claim 1, characterized in that: In any one of the steps S10 to S60, the lead screw to be straightened is moved by a conveying device; Wherein, the conveying device drives the lead screw to be straightened to move forward under the action of the driving device.

3. The low melting point alloy filling and straightening method according to claim 1, characterized in that: The melting point of the low melting point alloy is below 180°C.

4. The low melting point alloy filling and straightening method according to claim 1, characterized in that: The low melting point alloy includes one or more of tin, lead and bismuth.

5. The low melting point alloy filling and straightening method according to claim 1, characterized in that: The low melting point alloy includes bismuth element.

6. The low melting point alloy filling and straightening method according to claim 1, characterized in that: The mass fraction of bismuth element in the low melting point alloy is 37%-70%.

7. The low melting point alloy filling and straightening method according to claim 1, characterized in that: When the low melting point alloy changes from liquid to solid, the volume of the low melting point alloy expands or remains unchanged.

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