Method for machining threaded holes for titanium bars

Abstract

The application discloses a threaded hole machining method for a titanium rod, the threaded hole is arranged on a working section of the titanium rod, and the working section is made of titanium alloy material; the threaded hole machining method comprises the following steps: S1, a tungsten steel drill bit is selected to process a bottom hole with a preset size at one end of a workpiece to be machined; S2, a boring tool is used to bore the bottom hole to empty titanium slag debris in the bottom hole; S3, after the titanium slag debris in the bottom hole is emptied, a tapping tap is used to tap the bottom hole to form a threaded hole; wherein the tapping tap has a 30-35 degree rake angle and a 40 degree relief angle; S4, the threaded hole is bored by the boring tool to remove burrs left at the bottom of the threaded hole; the steps S3 and S4 are repeated until the inner thread specification of the threaded hole is #10-32UNF-2B, #10 is a number, 32 is a number of teeth, UNF represents fine thread, and 2B is the accuracy grade of the inner thread. The threaded hole machining method can reduce part rejection and improve the quality of the threaded hole.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of titanium rod, in particular to a threaded hole processing method for titanium rod. BACKGROUND

[0002] Referring to Figure 1 Fig. 1 shows a combined titanium rod electrode for disinfecting swimming pool water. Referring to Figure 2 Fig. 2 shows an exploded view of the combined titanium rod electrode. The combined titanium rod electrode comprises a working section 1 and a control section 2 connected by threads, a sealing ring 3 sleeved on the control section, and a bolt 4 connected to the control section. One end of the working section 1 is a slotted section for connecting titanium blades. The other end of the working section 1 is a blind hole with internal threads. The control section 2 comprises a connecting section, a first step, a groove, a second step, and external threads 21 arranged in sequence. The external threads 21 match the internal threads of the working section to form a threaded connection. The titanium rod electrode is divided into a working section 1 and a control section 2 connected by threads. When the working section 1 or the titanium blades have quality problems, the working section can be easily removed from the control section by threads and replaced with a new one without replacing the entire titanium rod electrode, thereby saving replacement costs and product costs.

[0003] However, since the working section is made of titanium alloy, the process characteristics of titanium alloy are that the newly formed surface after machining has high chemical activity and can easily form a deep cold hardening layer with oxygen, carbon, and nitrogen. It can also easily combine with the surface of the tap to form a firm metal compound, causing the tap to stick and wear.

[0004] Therefore, it is difficult to drill a hole at one end of the existing working section of the titanium rod electrode and tap the internal threads of 10-32UNF-2B. If a part is scrapped due to tap breakage on a nearly finished part, it will cause a lot of waste. SUMMARY

[0005] In order to overcome the defects in the prior art, the embodiments of the present application provide a threaded hole processing method for titanium rod, which can reduce part scrap and improve the quality of threaded holes.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is as follows: a threaded hole processing method for titanium rod, the threaded hole is arranged on the working section of the titanium rod, and the working section is made of titanium alloy; the threaded hole processing method comprises the following steps:

[0007] S1: selecting a tungsten steel drill bit to process a bottom hole of a predetermined size at one end of the workpiece to be processed;

[0008] S2: using a boring tool to bore the bottom hole to empty the titanium slag and debris in the bottom hole;

[0009] S3: after the titanium slag debris in the bottom hole is emptied, a tapping thread hole is formed by tapping the bottom hole using a tapping tap, wherein the tapping tap has a 30°-35° rake angle and a 40° relief angle;

[0010] S4: the tapping thread hole is processed by a boring tool to remove burrs left at the bottom of the hole during tapping;

[0011] The steps S3 and S4 are repeated until the internal thread specification of the tapping thread hole is #10-32UNF-2B, #10 is the number, 32 is the number of teeth, UNF represents fine thread, and 2B is the accuracy grade of the internal thread.

[0012] The titanium rod in the application includes a working section and a control section. An external thread is arranged on the control section, and an internal thread is arranged at one end of the working section to match the external thread, so that the control section and the working section can be connected through the threads. The internal thread specification of the working section is #10-32UNF-2B, #10 is the number, 32 is the number of teeth, UNF represents fine thread, and 2B is the accuracy grade of the internal thread. It is calculated that the small diameter size of the thread is 0.156-0.164in (3.96-4.16mm, 4.06±0.1mm). The tapped thread is a small-diameter deep hole thread.

[0013] The working section in the application is made of titanium alloy. When the hardness of the titanium alloy is greater than HB350, the cutting process is particularly difficult, and when the hardness is less than HB300, the tool sticking phenomenon easily occurs and the cutting process is also difficult. The titanium alloy has the characteristics of a small deformation coefficient. When the deformation coefficient of the titanium alloy is less than or close to 1, the sliding friction distance of the chip on the rake face is greatly increased, accelerating the tool wear. The titanium alloy also has the characteristics of high cutting temperature during tapping. Because the thermal conductivity coefficient of the titanium alloy is very small (only 1 / 5-1 / 7 of that of 45# steel), the contact length of the chip with the rake face is extremely short, the heat generated during cutting is not easy to be transmitted out, and is concentrated in a small range near the cutting zone and the cutting edge, and the cutting temperature is very high. Under the same cutting conditions, the cutting temperature can be more than doubled compared with that when cutting 45# steel. The titanium alloy also has the characteristics of large cutting force per unit area during tapping. Because the contact length of the chip with the rake face is extremely short, the cutting force per unit contact area is greatly increased, which easily causes the tool to break, and at the same time, because the elastic modulus of the titanium alloy is small, bending deformation is easily generated under the action of the radial force during machining, causing vibration, increasing tool wear, and affecting the accuracy of the part.

[0014] The inventor adjusts the standard tap by targeting the characteristics of the titanium alloy tapping, so that the tapping tap has a 30°-35° front angle and a 40° rear angle. The large front angle is beneficial to cutting long chip metal, but due to the sliding of the chip on the rake face during cutting, it will accelerate the wear of the tool. The small front angle of 30°-35° selected by the application can improve the cutting edge strength, thereby increasing the tool life. The large rear angle of 40° can reduce the friction between the tool and the chip. The inventor also found that the spiral flute tap is easier to discharge than the straight flute tap, so the spiral flute is selected for chip removal.

[0015] Further, in the internal thread machining method, the hole is tapped twice by using the tapping tap. Since the hole depth of the thread hole to be machined is 4.0-4.2 mm, it is a deep hole structure. After tapping the hole with the tapping tap for several times, it can be ensured that the thread is formed at the bottom of the hole, that is, it can be ensured that the tap can be screwed to the bottom along the thread during the gauge detection. The number of teeth that the stop gauge can be screwed into is not more than 2, which is the qualified tapping of the tapping tap.

[0016] Further, before tapping the bottom hole with the tapping tap, the guide angle of the front part of the tapping tap is also ground. Since the depth of the bottom hole is limited, titanium slag is easy to accumulate when the tap has a guide angle, so the guide angle of the front part of the tap is ground before use.

[0017] Further, in step S3, the model of the tapping tap is YAMAWA N-RS G610-32UNF, and the rotating speed of the tapping tap is 500 rpm. The inventor found that the selection and process of the tapping tap are very important during tapping. Since the titanium alloy material is hard and has high strength, the tap top is quickly dull, so the strength of the tap body is very important, and the tap material is preferably made of high-speed steel to have high toughness, red hardness, and anti-deformation and anti-wear performance. The application selects a customized tapping tap to adapt to the characteristics of titanium alloy tapping, meet the tapping requirements, and improve the service life of the tapping tap.

[0018] Further, in step S1, the specification of the tungsten steel drill bit is D4.1*18*5S*50L mm, and the rotating speed of the tungsten steel drill bit is 1560 rpm. Since the tapped thread is a small-diameter deep hole thread, in order to have better thread quality during tapping and to have high tapping efficiency and complete chip removal, we select a tungsten steel drill bit to drill the bottom hole. The specification of the drill bit is D4.1*18*5S*50L mm, and the drill bit diameter is larger in order to have a larger hole diameter after drilling, thereby providing a larger hole diameter space for the subsequent tapping of the tap and improving the chip removal efficiency.

[0019] Further, in step S2, the model of the boring tool is MTR 3R0.15 L15-D4, and the rotating speed of the boring tool is 2000 rpm. The hole wall after drilling is relatively rough and a large amount of titanium slag and debris is left in the bottom hole. The boring of the bottom hole by the boring tool can improve the quality of the hole wall and the size accuracy of the hole diameter.

[0020] Further, in step S1, the diameter of the bottom hole with the preset size is Φ4.0-4.1 mm, and the hole depth is 4.0-4.2 mm.

[0021] Further, after the boring of the bottom hole by the boring tool in step S2, the diameter of the bottom hole is 4.06±0.1 mm, and the hole depth is 4.0-4.2 mm.

[0022] Thanks to the above technical solution, the present application has the following advantages compared with the prior art:

[0023] 1. In the present application, the tap is adjusted according to the characteristics of the titanium alloy tapping, so that the tapping tap has a small front angle of 30°-35° and a rear angle of 40°, thereby improving the cutting edge strength, reducing the friction between the tool and the chip, and increasing the tool life.

[0024] 2. According to the specification and depth of the tapping, the thread plug gauge detection requirement, the appropriate drilling diameter and depth are determined, and the appropriate tungsten steel drill, boring tool and tapping tap are selected to improve the quality of the threaded hole.

[0025] 3. According to the machining characteristics of the machine tool and the structural characteristics of the product, different rotating speeds are set for the tungsten steel drill, boring tool and tapping tap to improve the quality of the threaded hole.

[0026] In order to make the above and other objects, features and advantages of the present application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0028] Figure 1 is a schematic diagram of a combined titanium rod electrode in the present application;

[0029] Figure 2 is an exploded schematic diagram of a combined titanium rod electrode in the present application;

[0030] Figure 3It is a flow chart of the threaded hole processing method of the application.

[0031] The reference numerals of the above drawings are as follows: 1, working section; 2, control section; 21, external thread; 3, sealing ring; 4, bolt. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0033] Embodiment one: a threaded hole processing method for a titanium rod, referring to Figure 1 、 2 As shown in the figure, the combined titanium rod electrode comprises a threaded working section 1 and a control section 2, a sealing ring 3 sleeved on the control section 2, and a bolt 4 connected to the control section. One end of the working section 1 is a slotted section for connecting a titanium blade. The other end of the working section 1 is a blind hole with internal thread. The control section 2 comprises a connecting section, a first step, a groove, a second step, and an external thread 21 arranged in sequence. The external thread 21 matches the internal thread of the working section 1 to form a threaded connection. The internal thread specification is #10-32UNF-2B, #10 is the number, 32 is the number of teeth, UNF represents fine thread, and 2B is the accuracy grade of the internal thread. It is calculated that the small diameter size of the thread is 0.156-0.164in (3.96-4.16mm, 4.06±0.1mm). The threaded hole is a small-diameter deep hole thread.

[0034] As shown in the figure, the threaded hole processing method comprises the following steps: Figure 3

[0035] S1: selecting a tungsten steel drill bit to process a bottom hole of a preset size at one end of a workpiece to be processed;

[0036] In this step, the specification of the tungsten steel drill bit is D4.1*18*5S*50Lmm, and the rotating speed of the tungsten steel drill bit is 1560 revolutions per minute. When the size of the bottom hole processed by the tungsten steel drill bit is in the range of diameter Φ4.0-4.1mm and hole depth 4.0-4.2mm, further drilling is stopped.

[0037] ​Since the thread to be tapped is a small-diameter deep-hole thread, in order to have better thread quality during tapping and to make tapping efficient and completely remove chips, the inventor selects a tungsten steel drill bit to drill the bottom hole, the drill bit specification is D4.1*18*5S*50L mm, the drill bit diameter is larger to make the hole diameter larger after drilling, thereby providing a larger hole diameter space for the tap to tap the thread, and thus improving the chip removal efficiency.

[0038] S2: boring the bottom hole with a boring tool to remove the titanium slag chips in the bottom hole;

[0039] In this step, the model of the boring tool is MTR 3R0.15 L 15-D4, and the rotating speed of the boring tool is 2000 rpm. After boring, the diameter of the bottom hole is 4.06±0.1 mm, and the hole depth is 4.0-4.2 mm, and further boring is stopped. The hole wall after drilling is relatively rough and a large amount of titanium slag and chips remain in the bottom hole. Boring the bottom hole with the boring tool can improve the hole wall quality and the hole diameter size accuracy.

[0040] S3: after removing the titanium slag chips in the bottom hole, tapping the bottom hole with an extrusion tap to form a threaded hole; wherein the extrusion tap has a 30°-35° rake angle and a 40° relief angle;

[0041] In this step, before tapping the bottom hole with the extrusion tap, the guide angle of the front part of the extrusion tap is also ground flat. Since the bottom hole has limited depth, titanium slag is easily accumulated when the tap has a guide angle, so the guide angle of the front part of the tap is ground flat before use.

[0042] In this step, the model of the extrusion tap is YAMAWA N-RS G610-32UNF, and the rotating speed of the extrusion tap is 500 rpm. By combining the characteristics of the titanium alloy tapping mentioned above, the standard tap is adjusted to have a 30°-35° small rake angle and a 40° relief angle to make a customized extrusion tap. Selecting a 30°-35° small rake angle can improve the cutting edge strength, thereby increasing the tool life. Selecting a 40° large relief angle can reduce the friction between the tool and the chips.

[0043] S4: boring the threaded hole with a boring tool;

[0044] This step can remove the burrs left in the hole bottom during tapping.

[0045] S5: repeating tapping with the extrusion tap;

[0046] After multiple tapping, it is ensured that the thread is formed at the bottom of the tap, that is, it is ensured that the go gauge can be screwed to the bottom along the thread. When the number of teeth that the stop gauge can be screwed into is not more than 2, the tap tapping is qualified.

[0047] The principles and implementation manners of the present application are described by using specific examples, and the above examples are only used for helping to understand the method of the present application and its core idea; meanwhile, for the general technical personnel in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed, and the above description should not be understood as the limitation of the present application.

Claims

1. A method for machining a threaded hole in a titanium rod, wherein the threaded hole is disposed on a working section of the titanium rod, and the working section is made of titanium alloy; characterized in that, The threaded hole machining method includes the following steps: S1: Use a tungsten carbide drill bit to machine a bottom hole of a preset size at one end of the workpiece; S2: Use a boring tool to bore the bottom hole to remove titanium slag debris from the bottom hole; S3: After emptying the titanium slag debris in the bottom hole, the bottom hole is tapped twice using a threaded tap to form a threaded hole; wherein the threaded tap has a front angle of 30° to 35° and a back angle of 40°. S4: Use a boring tool to bore the threaded hole to remove the burrs left at the bottom of the hole during tapping; Repeat steps S3 and S4 until the internal thread specification of the formed threaded hole is #10-32UNF-2B, where #10 is the number, 32 is the number of threads, UNF indicates fine thread, and 2B is the precision grade of the internal thread.

2. The method for machining threaded holes in titanium rods according to claim 1, characterized in that: Before tapping the hole with a toothed tap, the guide angle at the front of the toothed tap is ground flat.

3. The method for machining threaded holes in titanium rods according to claim 1, characterized in that: In step S3, the extrusion tap is model YAMAWA N-RS G6 10-32UNF, and the rotation speed of the extrusion tap is 500 rpm.

4. The method for machining threaded holes in titanium rods according to claim 1, characterized in that: In step S1, the tungsten carbide drill bit has the specifications of D4.1*18*5S*50Lmm and the rotation speed of the tungsten carbide drill bit is 1560 rpm.

5. The method for machining threaded holes in titanium rods according to claim 1, characterized in that: In step S2, the boring tool is of model MTR 3R0.15 L15-D4, and the boring tool rotates at 2000 rpm.

6. The method for machining threaded holes in titanium rods according to claim 1, characterized in that: In step S1, the diameter of the preset bottom hole is Φ4.0~4.1mm and the hole depth is 4.0~4.2mm.

7. The method for machining threaded holes in titanium rods according to claim 1, characterized in that: After boring the bottom hole with a boring tool in step S2, the diameter of the bottom hole is 4.06±0.1mm and the hole depth is 4.0~4.2mm.

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