Cutter bar and cutter for machining inner cavity of part

Abstract

The utility model provides a cutter bar and a cutter for machining an inner cavity of a part. The cutter bar comprises a first part, a second part and a third part. The first part comprises a first end and a second end, and the first end is used for installing a tool bit. The second part comprises a third end and a fourth end, and the third end is connected with the second end. The third part comprises a fifth end and a sixth end, and the fifth end is connected with the fourth end. Wherein the diameter of the second end of the first part is larger than that of the first end, the diameter of the fourth end of the second part is larger than that of the third end, and the diameter of the sixth end of the third part is equal to that of the fifth end. The second part is longer than the first part, and the second part is longer than the third part. Due to the two sections of variable diameters of the first part and the second part, the whole cutter bar has the advantages of mechanical strength and vibration prevention, large feeding is allowed to be adopted in the machining process, the machining stability is guaranteed, and the machining efficiency can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of mechanical processing, in particular to a tool rod and a tool for processing the inner cavity of a part. Background Art

[0002] When machining large parts (e.g., engine connector body parts), due to the large size of the parts, the inner cavity of the parts is very long and the aspect ratio (i.e., the ratio of length to diameter) of the inner cavity is large, for example, greater than or equal to 30:1, the length of the tool used needs to match the length of the inner cavity, for example, up to 600mm or even longer. When machining this type of inner cavity, traditional tools will experience tool vibration and tool yielding. On the one hand, it is impossible to use a large feed, resulting in low machining efficiency; on the other hand, the surface quality obtained by machining cannot meet the requirements. Utility Model Content

[0003] Therefore, the technical problem to be solved by the utility model is to overcome the problem that when the tool in the prior art processes parts with a relatively long aspect ratio, the tool rod will vibrate and let the tool go, resulting in low processing efficiency and low quality, thereby providing a tool rod and tool for processing the inner cavity of parts.

[0004] In a first aspect, the utility model provides a tool bar for machining an inner cavity of a part, comprising:

[0005] A first portion including a first end and a second end, wherein the first end is used to mount a cutter head;

[0006] A second portion, comprising a third end and a fourth end, wherein the third end is connected to the second end;

[0007] A third part, comprising a fifth end and a sixth end, wherein the fifth end is connected to the fourth end;

[0008] Among them, the diameter of the second end of the first part is larger than the diameter of the first end, the diameter of the fourth end of the second part is larger than the diameter of the third end, and the diameter of the sixth end of the third part is equal to the diameter of the fifth end; the length of the second part is larger than the length of the first part, and the length of the second part is larger than the length of the third part.

[0009] Optionally, a ratio of the diameter of the first end to the diameter of the second end ranges from 0.3 to 0.7.

[0010] Optionally, a ratio of the diameter of the first end to the diameter of the second end is 0.5.

[0011] Optionally, the ratio of the diameter of the third end to the diameter of the fourth end ranges from 0.7 to 0.9.

[0012] Optionally, the ratio of the diameter of the third end to the diameter of the fourth end is 0.8.

[0013] Optionally, it is characterized in that the ratio of the diameter of the first end to the length of the first part ranges from 0.08 to 0.16.

[0014] Optionally, a ratio of a diameter of the first end to a length of the first portion is 0.118.

[0015] Optionally, a ratio of a diameter of the third end to a length of the second portion ranges from 0.1 to 0.18.

[0016] Optionally, a ratio of a diameter of the third end to a length of the second portion is 0.133.

[0017] Optionally, a ratio of a diameter of the fifth end to a length of the third portion ranges from 0.34 to 0.42.

[0018] Optionally, a ratio of the diameter of the fifth end to the length of the third portion is 0.385.

[0019] Optionally, a ratio of the length of the first portion to the length of the second portion ranges from 0.54 to 0.06; and a ratio of the length of the second portion to the length of the third portion ranges from 2.27 to 2.35.

[0020] Optionally, a ratio of the length of the first portion to the length of the second portion is 0.567; and a ratio of the length of the second portion to the length of the third portion is 2.308.

[0021] Optionally, the first part, the second part and the third part are made of tungsten steel alloy material.

[0022] In a second aspect, the utility model provides a cutting tool, comprising the above-mentioned cutting rod and a cutting head.

[0023] The utility model has the following advantages:

[0024] The utility model provides a tool rod for processing the inner cavity of a part, comprising: a first part, a second part and a third part. The first part comprises a first end and a second end, and the first end is used to install a tool head. The second part comprises a third end and a fourth end, and the third end is connected to the second end. The third part comprises a fifth end and a sixth end, and the fifth end is connected to the fourth end. The diameter of the second end of the first part is greater than the diameter of the first end, the diameter of the fourth end of the second part is greater than the diameter of the third end, and the diameter of the sixth end of the third part is equal to the diameter of the fifth end. The length of the second part is greater than the length of the first part, and the length of the second part is greater than the length of the third part.

[0025] When in use, the cutter head can be installed at the first end of the first part, and the inner cavity of the part can be processed by using the first end. The first part and the second part are both reduced in diameter, and have a vibration reduction effect from the first end to the second end of the first part, and also have a vibration reduction effect from the third end to the fourth end of the second part. Such a setting can greatly reduce the vibration amplitude of the entire tool bar, improve the vibration resistance of the tool bar, and thus avoid vibration and tool letting during the process of processing the inner cavity of the part. Moreover, the length of the second part is greater than the length of the first part and also greater than the length of the third part, so that the tool bar as a whole takes into account the two major advantages of mechanical strength and vibration avoidance, so that a larger feed can be used during the processing process, thereby ensuring the stability of the processing and improving the efficiency of the processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of the structure of the knife bar in this embodiment is shown;

[0028] Figure 2 Shows Figure 1 A side view of the tool bar shown;

[0029] Figure 3 Shows Figure 2 A schematic diagram of a partial cross-sectional structure of the end of the shank shown;

[0030] Figure 4 The schematic diagram of the structure of the tool in this embodiment is shown;

[0031] Figure 5 Shows Figure 4 A schematic diagram of the side view of the tool shown;

[0032] Figure 6 Shows Figure 5 A schematic diagram of the partial cross-sectional structure of the end of the tool is shown.

[0033] Description of reference numerals:

[0034] 100, knife rod; 110, first part; 112, first end; 114, second end; 120, second part; 122, third end; 124, fourth end; 130, third part; 132, fifth end; 134, sixth end; 140, knife head. DETAILED DESCRIPTION

[0035] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0036] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the tool bar for machining the inner cavity of a part provided by the utility model comprises: a first part 110 , a second part 120 and a third part 130 .

[0040] The first portion 110 includes a first end 112 and a second end 114 , and the first end 112 is used to mount a tool head 140 .

[0041] The second portion 120 includes a third end 122 and a fourth end 124 , and the third end 122 is connected to the second end 114 .

[0042] The third portion 130 includes a fifth end 132 and a sixth end 134, and the fifth end 132 is connected to the fourth end 124. The first end 112, the second end 114, the third end 122, the fourth end 124, the fifth end 132 and the sixth end 134 are defined according to the diameter change position of the tool rod, so as to more clearly explain the diameter change size and position, but are not intended to limit the specific structure of the tool rod. The first portion 110, the second portion 120 and the third portion 130 of the tool rod 100 can be integrally formed.

[0043] The diameter of the second end 114 of the first portion 110 is greater than the diameter of the first end 112, the diameter of the fourth end 124 of the second portion 120 is greater than the diameter of the third end 122, and the diameter of the sixth end 134 of the third portion 130 is equal to the diameter of the fifth end 132. The length of the second portion 120 is greater than the length of the first portion 110, and the length of the second portion 120 is greater than the length of the third portion 130.

[0044] When in use, the cutter head 140 can be installed at the first end 112 of the first part 110, and the inner cavity of the part can be processed by using the first end 112. The first part 110 and the second part 120 are both reduced in diameter, and the first end 112 to the second end 114 of the first part 110 has a vibration reduction effect, and the third end 122 to the fourth end 124 of the second part 120 also has a vibration reduction effect. Such a setting can greatly reduce the vibration amplitude of the entire tool bar, improve the vibration resistance of the tool bar, and thus avoid vibration and tool letting during the process of processing the inner cavity of the part. Moreover, the length of the second part 120 is greater than the length of the first part 110, and also greater than the length of the third part 130, so that the tool bar as a whole takes into account the two advantages of mechanical strength and vibration avoidance, so that a larger feed can be used during the processing process, thereby ensuring the stability of the processing and improving the efficiency of the processing.

[0045] In this embodiment, the ratio of the diameter of the first end 112 to the diameter of the second end 114 is in the range of 0.3 to 0.7. Figure 1As shown, the diameter of the second end 114 is greater than the diameter of the first end 112. The first end 112 is the end closest to the processing part during operation. The cutter head 140 installed at the first end 112 will transfer energy from the first end 112 to the first part 110, the second part 120 and the third part 130 during cutting, thereby causing the first part 110, the second part 120 and the third part 130 to vibrate. The diameter of the first end 112 is smaller than the diameter of the second end 114, so that the wave impedance from the first end 112 to the second end 114 gradually increases, so that the vibration wave encounters gradually increasing resistance when transmitting from the first end 112 to the second end 114, and the discontinuous impedance wave will change the propagation characteristics of the vibration wave, so that part of the vibration wave energy returns to the first end 112, so that the vibration wave energy absorbed by the second end 114 can be greatly reduced, thereby reducing the vibration amplitude and vibration frequency of the second end, thereby playing a vibration reduction role. That is, the smaller the diameter ratio of the first end 112 to the second end 114 is, the lower the vibration wave energy absorbed by the second end 114 is, and the smaller the vibration amplitude and vibration frequency of the second end 114 are. However, if the diameter of the first end 112 is too small, it will affect the overall mechanical strength of the first part 110, and the tool rod may break or deform during the processing. Therefore, the applicant has conducted a large number of experiments and found that if the ratio of the diameter of the first end 112 to the diameter of the second end 114 is less than 0.3, the mechanical strength of the first part 110 is insufficient. If the ratio of the diameter of the first end 112 to the diameter of the second end 114 is greater than 0.7, the anti-vibration effect is poor. Therefore, setting the ratio of the diameter of the first end 112 to the diameter of the second end 114 in the range of 0.3 to 0.7 can take into account the mechanical strength of the first part 110 and can greatly reduce the vibration of the first part 110.

[0046] Preferably, a ratio of a diameter of the first end 112 to a diameter of the second end 114 is in a range of 0.35 to 0.65.

[0047] Preferably, the ratio of the diameter of the first end 112 to the diameter of the second end 114 is in the range of 0.4 to 0.6.

[0048] Preferably, a ratio of a diameter of the first end 112 to a diameter of the second end 114 is in a range of 0.45 to 0.55.

[0049] Preferably, the ratio of the diameter of the first end 112 to the diameter of the second end 114 is in the range of 0.3 to 0.7.

[0050] Further preferably, the ratio of the diameter of the first end 112 to the diameter of the second end 114 is 0.5. When the ratio of the diameter of the first end to the diameter of the second end is 0.5, the mechanical strength requirement of the first part 110 can be met and the vibration reduction effect can be maximized. For example, the diameter of the first end 112 of the first part 110 can be 20 mm, and the diameter of the second end 114 of the first part 110 can be 40 mm.

[0051] Similarly, the ratio of the diameter of the third end 122 of the second part 120 to the diameter of the fourth end 124 is in the range of 0.7 to 0.9. In practical applications, the second part 120 is used to connect the first part 110 and the third part 130. The second part 120 needs to have sufficient mechanical strength to ensure that the power of the third part 130 is transmitted to the first part 110, and the second part 120 also needs to provide sufficient support force to the first part 110 so that it is located in the first part 110. In this way, the length of the second part 120 is greater than the length of the first part 110 and the length of the third part 130. However, the longer the length of the tool rod 100 is, the greater its vibration amplitude and the higher its vibration frequency are. Therefore, the second part 120 is the longest part of the tool rod 100, so the second part 120 The same diameter reduction treatment is required. After a large number of experiments, the applicant found that if the ratio of the diameter of the third end 122 to the diameter of the fourth end 124 is less than 0.7, the mechanical strength of the second part 120 will be insufficient. If the ratio of the diameter of the third end 122 to the diameter of the fourth end 124 is greater than 0.9, the anti-vibration effect will be poor. Therefore, when the ratio of the diameter of the third end 122 of the second part 120 to the diameter of the fourth end 124 is in the range of 0.7 to 0.9, it can not only meet the mechanical strength requirements, but also greatly reduce the vibration of the second part 120. The principle is the same as the vibration reduction principle of the first part 110 mentioned above, which will not be repeated here.

[0052] Preferably, a ratio of a diameter of the third end 122 of the second portion 120 to a diameter of the fourth end 124 is in a range of 0.72 to 0.88.

[0053] Preferably, a ratio of a diameter of the third end 122 of the second portion 120 to a diameter of the fourth end 124 is in a range of 0.74 to 0.86.

[0054] Preferably, a ratio of a diameter of the third end 122 of the second portion 120 to a diameter of the fourth end 124 is in a range of 0.76 to 0.84.

[0055] Preferably, a ratio of a diameter of the third end 122 of the second portion 120 to a diameter of the fourth end 124 is in a range of 0.78 to 0.82.

[0056] Further preferably, the ratio of the diameter of the third end 122 of the second part 120 to the diameter of the fourth end 124 is 0.8. When the ratio of the diameter of the third end 122 to the diameter of the fourth end 124 is 0.8, the mechanical strength requirement of the second part 120 can be met and the vibration reduction effect can be maximized. For example, the diameter of the third end 122 of the second part 120 can be 40 mm, and the diameter of the fourth end of the second part 120 can be 50 mm.

[0057] It can be seen from the two sections of diameter changes of the first part 110 and the second part 120 that such a configuration can not only ensure the mechanical strength of the first part 110 and the second part 120 , but also greatly reduce the vibration amplitude and vibration frequency of the first part 110 and the second part 120 .

[0058] The ratio of the diameter to the length of the tool bar 100 will also affect the anti-vibration effect of the tool bar 100. Since it is necessary to process a part with a large aspect ratio, such as an inner cavity with an aspect ratio of 10:1 or above, the overall length of the tool bar 100 will be very long, which increases the overall vibration amplitude and vibration frequency of the tool bar 100. For example, conventional anti-vibration tool bars are cylindrical with a diameter of 20 to 30 mm and a length of about 200 mm. They cannot be used to process inner cavities with a large length and a large aspect ratio (for example, a length exceeding 200 mm and an aspect ratio exceeding 10:1).

[0059] In order to solve the above problems, the ratio of the diameter of the first end 112 of the first part 110 to the length of the first part 110 of this embodiment is in the range of 0.08 to 0.16. The applicant has found through a large number of experiments that when the ratio of the diameter of the first end 112 to the length of the first part 110 is less than 0.08, the mechanical strength requirement cannot be met, and when the ratio of the diameter of the first end 112 to the length of the first part 110 is greater than 0.16, the anti-vibration effect is poor. Therefore, the ratio of the diameter of the first end 112 to the length of the first part 110 is set in the range of 0.08 to 0.16, which can not only ensure the processing size requirements, but also meet the mechanical strength requirements, and also have a good anti-vibration effect.

[0060] Preferably, a ratio of a diameter of the first end 112 of the first portion 110 to a length of the first portion 110 is in a range of 0.09 to 0.15.

[0061] Preferably, a ratio of a diameter of the first end 112 of the first portion 110 to a length of the first portion 110 ranges from 0.10 to 0.14.

[0062] Preferably, a ratio of a diameter of the first end 112 of the first portion 110 to a length of the first portion 110 is in a range of 0.11 to 0.13.

[0063] Further preferably, the ratio of the diameter of the first end 112 of the first part 110 to the length of the first part 110 is in the range of 0.118. When the ratio of the diameter of the first end 112 to the length of the first part 110 is 0.118, the length dimension requirement of the first part 110 can be met and the vibration reduction effect can be maximized.

[0064] It should be understood that in this embodiment, the length of the first part 110 is designed with reference to the diameter of the first end 112, and the length of the second end 114 is set based on the diameter of the first end 112, so the ratio range of the diameter of the second end 114 and the length of the first part 110 is not repeatedly set here.

[0065] Similarly, in this embodiment, the ratio of the diameter of the third end 122 to the length of the second portion 120 is in the range of 0.1 to 0.18. The applicant has found through a large number of experiments that when the ratio of the diameter of the third end 122 to the length of the second portion 120 is less than 0.1, the mechanical strength requirement cannot be met, and when the ratio of the diameter of the third end 122 to the length of the second portion 120 is greater than 0.18, the anti-vibration effect is poor. Therefore, the ratio of the diameter of the third end 122 to the length of the second portion 120 is set in the range of 0.1 to 0.18, which can not only ensure the processing size requirements, but also meet the mechanical strength requirements, and also have a good anti-vibration effect.

[0066] Preferably, the ratio of the diameter of the third end 122 to the length of the second portion 120 is in a range of 0.11 to 0.17.

[0067] Preferably, the ratio of the diameter of the third end 122 to the length of the second portion 120 is in a range of 0.12 to 0.16.

[0068] Preferably, the ratio of the diameter of the third end 122 to the length of the second portion 120 is in a range of 0.13 to 0.15.

[0069] Further preferably, the ratio of the diameter of the third end 122 to the length of the second portion 120 is 0.133. When the ratio of the diameter of the third end 122 to the length of the second portion 120 is 0.133, the length dimension requirement of the second portion 120 can be met and the vibration reduction effect can be maximized.

[0070] For the same reason, in this embodiment, the ratio of the diameter of the fourth end 124 to the length of the second portion 120 is not repeatedly set.

[0071] The third part 130 is an end connected to the driving mechanism, and needs to maintain sufficient mechanical strength and have a certain anti-vibration ability. In this embodiment, the ratio of the diameter of the fifth end 132 to the length of the third part 130 is in the range of 0.34 to 0.42. When the ratio of the diameter of the fifth end 132 to the length of the third part 130 is less than 0.34, the mechanical strength requirement cannot be met. When the ratio of the diameter of the fifth end 132 to the length of the third part 130 is greater than 0.42, the anti-vibration effect is poor. Therefore, the ratio of the diameter of the fifth end 132 to the length of the third part 130 is set in the range of 0.34 to 0.42, which can not only ensure the processing size requirements, but also meet the mechanical strength requirements, and also have a good anti-vibration effect.

[0072] Preferably, a ratio of the diameter of the fifth end 132 to the length of the third portion 130 is in a range of 0.35 to 0.41.

[0073] Preferably, a ratio of the diameter of the fifth end 132 to the length of the third portion 130 is in a range of 0.36 to 0.4.

[0074] Preferably, a ratio of the diameter of the fifth end 132 to the length of the third portion 130 is in a range of 0.37 to 0.39.

[0075] Further preferably, the ratio of the diameter of the fifth end 132 to the length of the third portion 130 is 0.385. When the ratio of the diameter of the fifth end 132 to the length of the third portion 130 is 0.385, the length dimension requirement of the third portion 130 can be met and the vibration reduction effect can be maximized.

[0076] In order to ensure the length dimension requirements, mechanical strength requirements and vibration resistance requirements of the tool rod 100, on the basis of the above, the ratio of the length of the first part 110 to the length of the second part 120 ranges from 0.54 to 0.06, and the ratio of the length of the second part 120 to the length of the third part 130 ranges from 2.27 to 2.35.

[0077] Preferably, the ratio of the length of the first portion 110 to the length of the second portion 120 is 0.567, and the ratio of the length of the second portion 120 to the length of the third portion 130 is 2.308. For example, the length of the first portion 110 may be 170 mm, the length of the second portion 120 may be 300 mm, and the length of the third portion 130 may be 130 mm.

[0078] In this embodiment, the first part 110, the second part 120 and the third part 130 are made of tungsten steel alloy material. Tungsten steel alloy has very high strength and hardness, is not easy to deform and bend during processing, can play a good role in shock resistance, and avoids the phenomenon of tool deflection.

[0079] like Figure 2 and Figure 3 As shown, in this embodiment, the first end 112 of the first portion 110 of the knife rod 100 has an internal thread, and the internal thread is used to engage with the external thread of the knife head 140 to assemble the knife rod 100 and the knife head 140 together. Figure 3 As shown, a section A of a first end 112 of a first portion 110 of a knife rod 100 is shown, and the first end 112 of the first portion 110 of the knife rod 100 has an internal thread.

[0080] like Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, in this embodiment, a tool is provided, including a tool head 140 and a tool rod 100, and the tool rod 100 and the tool head 140 are assembled together by screwing together an internal thread and an external thread.

[0081] The tool rod 100 of the tool provided in this embodiment is exactly the same as the tool rod 100 in the above embodiment, and has the anti-vibration effect and structural strength of the above tool rod 100, which can ensure that a larger feed is allowed during the processing, thereby ensuring the stability of the processing and improving the efficiency of the processing.

[0082] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A tool bar for machining the inner cavity of a part, characterized in that: include: A first portion (110) includes a first end (112) and a second end (114), wherein the first end (112) is used to mount a cutter head; A second portion (120) comprising a third end (122) and a fourth end (124), wherein the third end (122) is connected to the second end (114); A third portion (130), comprising a fifth end (132) and a sixth end (134), wherein the fifth end (132) is connected to the fourth end (124); The diameter of the second end (114) of the first part (110) is greater than the diameter of the first end (112), the diameter of the fourth end (124) of the second part (120) is greater than the diameter of the third end (122), and the diameter of the sixth end (134) of the third part (130) is equal to the diameter of the fifth end (132); the length of the second part (120) is greater than the length of the first part (110), and the length of the second part (120) is greater than the length of the third part (130).

2. The tool bar for machining the inner cavity of a part according to claim 1, characterized in that: A ratio of a diameter of the first end (112) to a diameter of the second end (114) ranges from 0.3 to 0.

7.

3. The tool bar for machining the inner cavity of a part according to claim 2, characterized in that: The ratio of the diameter of the first end (112) to the diameter of the second end (114) is 0.

5.

4. The tool bar for machining the inner cavity of a part according to claim 1, characterized in that: The ratio of the diameter of the third end (122) to the diameter of the fourth end (124) ranges from 0.7 to 0.

9.

5. The tool bar for machining the inner cavity of a part according to claim 4, characterized in that: The ratio of the diameter of the third end (122) to the diameter of the fourth end (124) is 0.

8.

6. The tool bar for machining the inner cavity of a part according to any one of claims 1 to 5, characterized in that: A ratio of a diameter of the first end (112) to a length of the first portion (110) ranges from 0.08 to 0.

16.

7. The tool bar for machining the inner cavity of a part according to claim 6, characterized in that: The ratio of the diameter of the first end (112) to the length of the first portion (110) is 0.

118.

8. The tool bar for machining the inner cavity of a part according to any one of claims 1 to 5, characterized in that: A ratio of a diameter of the third end (122) to a length of the second portion (120) ranges from 0.1 to 0.

18.

9. The tool bar for machining the inner cavity of a part according to claim 8, characterized in that: The ratio of the diameter of the third end (122) to the length of the second portion (120) is 0.

133.

10. The tool bar for machining the inner cavity of a part according to any one of claims 1 to 5, characterized in that: A ratio of a diameter of the fifth end (132) to a length of the third portion (130) ranges from 0.34 to 0.

42.

11. The tool bar for machining inner cavities of parts according to claim 10, characterized in that: The ratio of the diameter of the fifth end (132) to the length of the third portion (130) is 0.

385.

12. The tool bar for machining inner cavities of parts according to claim 1, characterized in that: The ratio of the length of the first portion (110) to the length of the second portion (120) ranges from 0.54 to 0.06; and the ratio of the length of the second portion (120) to the length of the third portion (130) ranges from 2.27 to 2.

35.

13. The tool bar for machining the inner cavity of a part according to claim 12, characterized in that: The ratio of the length of the first portion (110) to the length of the second portion (120) is 0.567; and the ratio of the length of the second portion (120) to the length of the third portion (130) is 2.

308.

14. The tool bar for machining inner cavities of parts according to claim 1, characterized in that: The first part (110), the second part (120) and the third part (130) are made of tungsten steel alloy material.

15. A cutting tool, characterized in that: The invention comprises a tool rod (100) for machining the inner cavity of a part according to any one of claims 1 to 14, and also comprises a tool head (140).

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