Thread turning insert

Abstract

The application discloses a thread turning blade, which comprises a body, an angular cutting edge formed on the outer edge of the body and matched with a thread groove, the angular cutting edge has an edge center line, an upper surface of the body is offset inward along the edge center line by two edge parts of the angular cutting edge, and a front edge surface, a chip groove and a first protruding part are sequentially formed, the front edge surface and the chip groove are inclined inward along the edge center line and toward a lower surface of the body by a certain angle, the first protruding part is upwardly and obliquely extended from the lowest position of the chip groove, and at least a straight surface section is formed at a position higher than the front edge surface to make the chip move along the straight surface section. The thread turning blade has the advantages of simple structure, simple manufacturing, easy realization and low cost, and solves the problems of the existing thread cutting blade, such as difficulty in chip winding and chip breaking, large cutting force and easy vibration and chipping in the machining process.

Description

Technical Field

[0001] This invention relates to the field of cutting tool manufacturing technology, specifically to a thread turning insert. Background Technology

[0002] Thread turning is a widely used method for machining thread grooves, and automated production lines have been gradually adopted across various industries. To ensure high-quality and efficient machining, thread turning tools must meet requirements such as easy chip breaking, smooth chip removal, and stable chip life. Because thread turning involves various industries, a wide variety of materials, and numerous machine tools, chip breaking and removal have become significant challenges. Furthermore, due to the large overall metal removal and feed rate in thread turning, multi-step cutting is generally employed. In the first half of the machining process, the actual cutting area is smaller, the depth of cut is larger, and the chip thickness is greater, making chip breaking and removal relatively easy. The chip breaking and removal effect is achieved by curling the rake face. However, in the latter half, as the total depth of cut increases, the actual cutting area becomes longer (i.e., the cutting area becomes larger), leading to a corresponding increase in cutting force. To reduce cutting force, the depth of cut per pass is generally gradually reduced, resulting in thinner chips, decreased bending strength, and a smaller radius of curvature at which breakage occurs. This makes it difficult for chips to break through the rake face, which can easily lead to chips entangled in the workpiece or tool holder. As the workpiece rotates at high speed, chips can easily hit the tool tip or the tool tip can machine already processed chips, resulting in unstable machining. Ultimately, this can lead to chipping or unstable tool life, scratches on the workpiece surface, and decreased dimensional accuracy.

[0003] Furthermore, since the depth of cut in the latter half of the machining is smaller, extrusion processing is prone to occur, especially for some soft or sticky materials, which are prone to built-up edge. As we all know, the formation and periodic shedding of built-up edge is most likely to cause damage to the cutting edge of the tool, thereby affecting the tool life and the surface finish of the workpiece.

[0004] To mitigate the aforementioned risks, manufacturers on the market design chip breaker grooves on thread cutting inserts, including through-groove designs, boss designs, and recessed designs. While these methods can reduce certain risks, they still cannot meet all machining requirements. Specifically: through-groove designs can achieve smooth chip removal, but they cannot solve the chip breaking and built-up edge problems in the latter half of thread turning; boss designs can solve the chip breaking problem, but they have significant limitations, and this design has a drawback: the corresponding cutting force increases, making it prone to vibration. Vibration during machining directly affects surface finish and increases the risk of tool breakage; the third type, recessed designs, can effectively improve sharpness and are suitable for machining soft materials, but they also cannot solve the chip breaking problem in the latter half of the machining process.

[0005] In conclusion, existing thread cutting inserts still require further improvement. Summary of the Invention

[0006] The purpose of this invention is to overcome the aforementioned defects or problems in the prior art and to provide a thread turning insert that is simple in structure, easy to manufacture, easy to implement and low in cost, and solves the problems of existing thread cutting inserts being difficult to roll and break chips, having high cutting forces, and being prone to vibration and chipping during processing.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A thread turning insert includes a body and an angular cutting edge formed on the outer edge of the body and adapted to a thread groove, the angular cutting edge having a cutting center line; on the upper surface of the body and with the two cutting portions of the angular cutting edge offset inward along the cutting center line, a rake face, a chip groove, and a first protrusion are sequentially formed; the rake face and the chip groove are inclined at a certain angle inward along the cutting center line and toward the lower surface of the body; the first protrusion extends obliquely upward from the lowest position of the chip groove and forms at least one straight section above the rake face, so that the chip moves along the straight section.

[0009] Preferably, the two cutting edges of the angular cutting edge are respectively connected to the outer edge of the body via an arc surface transition, and the distance from the arc surface to the first protrusion is less than the distance from the intersection of the two cutting edges to the first protrusion.

[0010] Preferably, the chip groove is trapezoidal in cross-section along the center line of the blade, and the bottom of the chip groove is arranged to slope downward from near the intersection of the two blades toward the first protrusion.

[0011] Preferably, the surface within the chip groove that contacts the front cutting edge is configured as an adjacent surface, and the adjacent surface is inclined.

[0012] Preferably, the cross-section of the chip groove is triangular or trapezoidal; the depth of the chip groove is 0.02-0.2mm, and the distance from the edge of the adjacent surface to the intersection of the two cutting edges is 0.1-0.5mm.

[0013] Preferably, the chip-guiding surface of the first protrusion extends in a streamlined inclination towards the interior of the body along the center line of the cutting edge, and forms a sequentially connected transition arc section, the straight section, the inlet section, and the end extension section; the transition arc section is smoothly connected to the chip-receiving groove, and the straight section is located between the transition arc section and the inlet section; the inlet section has an arc and borders the end extension section.

[0014] Preferably, the body is further provided with at least two second protrusions, which are symmetrically arranged on both sides of the first protrusion with respect to the center line of the blade; the convex surfaces of the two second protrusions for shredding are inclined toward the intersection of the two blades and are set at an acute angle to the center line of the blade, so that the shredding gathers toward the intersection of the two blades.

[0015] Preferably, the highest position of the second protrusion is lower than the highest position of the end extension and higher than the lowest position of the end extension.

[0016] Preferably, the body is further provided with a chip guide protrusion, which is disposed on the side of the second protrusion and has a height greater than that of the second protrusion.

[0017] Preferably, the angle between the straight section and the upper surface of the body ranges from 10° to 35°.

[0018] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) This invention provides a thread turning insert, which is simple in structure, easy to manufacture, easy to implement, and low in cost. It solves the problems of existing thread cutting inserts, such as difficulty in chip curling and breaking, high cutting force, and easy vibration and chipping during machining. This invention forms a front cutting surface, a chip groove, and a first protrusion on the upper surface of the body and offset inward along the cutting center line. During the cutting process, it is beneficial to control chip accumulation, curling, and removal. The design of the chip groove reduces the contact area between the chips generated during machining and the front cutting surface, thereby reducing the cutting force and effectively reducing machining vibration. In addition, after the chips fall into the chip groove, they move upward from the groove to the first protrusion. This method controls the chip flow direction and curling, effectively preventing chips from scratching the machined surface or moving due to random movement. The process involves secondary cutting of the machined surface. Furthermore, the chips moving upwards from the chip groove move obliquely upwards along the first protrusion, guided by the straight section to extend further to the rear, effectively catching the flowing (moving) chips. This significantly reduces cutting force, especially in the latter half of thread machining (the stage where the angular cutting edge participates in the cutting area). At this stage, the cutting force is high, leading to machining difficulty. A slightly larger feed rate results in vibration and chipping due to the high cutting force, while a small feed rate makes it difficult to roll up the chip, resulting in built-up edge. The design of this invention is ingenious, using the arc from the chip groove to the first protrusion and then to the straight section to guide chip formation, effectively reducing the cutting force in the latter half of thread machining while successfully solving the chip breaking and removal problems in this stage.

[0020] (2) The two cutting edges of the angular cutting edge of the present invention are respectively connected to the outer edge of the body by an arc surface transition, and the distance from the arc surface to the first protrusion is less than the distance from the intersection of the two cutting edges to the first protrusion. This setting allows the chips from the two cutting edges of the angular cutting edge and the arc surface transition position connected to the finishing edge to flow to the first protrusion more quickly during the second half of the machining, ensuring that the rear part of the chip curls. The chips at the intersection of the two cutting edges pass through the chip groove to the first protrusion, which can effectively reduce the cutting force. This design can effectively solve the problem of large cutting force and difficult chip breaking and removal in the second half of thread machining.

[0021] (3) The present invention describes a chip groove with a trapezoidal cross-section along the center line of the cutting edge, and the bottom of the chip groove is arranged downward from near the intersection of the two cutting edges towards the first protrusion; in addition, the transverse cross-section of the chip groove is triangular or trapezoidal; the depth of the chip groove is 0.02-0.2mm, and the distance from the edge of the adjacent surface to the intersection of the two cutting edges is 0.1-0.5mm. Setting the chip groove as trapezoidal and having a triangular cross-section is beneficial for controlling the entry of chips into the chip groove, which not only ensures the sharpness of the cutting edge, reduces cutting force, and reduces machining vibration, but also reduces the friction between the chips and the rake face, reduces crater wear, and ensures that the chips can be effectively transferred to the rear in the second half of the thread machining. More importantly, it can ensure the overall strength and stability; on the other hand, it is beneficial for the storage and flow of coolant to remove more heat, resulting in better cooling effect.

[0022] (4) The first protrusion of the present invention is provided with a transition arc section, a straight section, an introductory section and an end extension section connected in sequence; the first protrusion is symmetrically distributed along the center line of the cutting edge, which is conducive to achieving chip rolling and chip removal effects in different tool feed methods. The transition arc section is connected to the chip groove, which can effectively receive the chips flowing from the chip groove. Through the smooth arc transition, it plays a chip rolling role in the first half of the machining and a chip guiding role in the second half of the machining. In addition, to solve the chip rolling problem in the second half, the planar straight section and the introductory section are combined to better solve the chip rolling and chip removal problem in the second half of the thread machining.

[0023] (5) The present invention also provides two second protrusions on both sides of the first protrusion, and the convex surface of the second protrusion is inclined towards the intersection of the two blades. That is, the two second protrusions are designed with an acute angle relative to the center line of the blade along the intersection of the two blades. This is beneficial to ensure that the chips can be well gathered towards the middle first protrusion regardless of whether the cutting method is radial or axial alternating. This effectively controls the chip discharge direction and achieves good chip rolling and chip breaking effects, ensuring that the chips are not easy to contact the machined surface again. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments are briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a three-dimensional structural diagram of the cutting blade described in this invention;

[0026] Figure 2 This is a top view of the cutting blade described in this invention;

[0027] Figure 3 This is a side view of the cutting blade described in this invention;

[0028] Figure 4 As described in this invention Figure 2 Enlarged view of part A in the image;

[0029] Figure 5 As described in this invention Figure 4 A cross-sectional view along the BB line.

[0030] Figure label:

[0031] 1. Body; 10. Finishing edge; 11. Outer edge; 12, 13, 14. Sidewall; 2. Angular cutting edge; 20. Intersection of two cutting edges; 21, 22. Two cutting edges; 3. Front cutting face; 4. Chip groove; 41. Groove bottom; 42. Adjacent surface; 5. First protrusion; 51. Lowest position; 52. Transition arc section; 53. Straight section; 54. Leading section; 55. Ending extension section; 6. Second protrusion; 61. Convex surface; 7. Chip guiding protrusion; C. Cutting edge centerline; γ. Angle between the straight section and the upper surface of the body. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are preferred embodiments of the present invention and should not be considered as excluding other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise expressly defined, the terms "first," "second," or "third" used in the claims, description, and accompanying drawings of this invention are for distinguishing different objects and not for describing a specific order.

[0034] Unless otherwise expressly defined, in the claims, description, and accompanying drawings of this invention, the use of directional terms such as "center," "lateral," "longitudinal," "horizontal," "vertical," "top," "bottom," "inner," "outer," "upper," "lower," "front," "rear," "left," "right," "clockwise," and "counterclockwise" to indicate orientation or positional relationships is based on the orientation and positional relationships shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the specific scope of protection of this invention.

[0035] Unless otherwise expressly defined, the terms "fixed connection" or "fixed connection" used in the claims, description and drawings of this invention should be interpreted broadly to refer to any connection in which there is no displacement or relative rotation relationship between the two parties, including non-removable fixed connection, detachable fixed connection, integral connection and fixed connection by other means or components.

[0036] In the claims, description and the above drawings of this invention, the use of the terms "comprising", "having" and variations thereof is intended to mean "including but not limited to".

[0037] See Figure 1 , Figure 2 and Figure 4 A thread turning insert includes a triangular body 1 and an angular cutting edge 2 formed on the outer edge 11 of the body 1 and adapted to the thread groove. The angular cutting edge has a center line C. The thread turning insert is generally mounted on a tool holder and fixed by screws. The thread turning insert is generally triangular and has at least one angular cutting edge 2 protruding from its outer edge 11 (i.e., at the junction with the outer edges 11 of the other two side walls). (Generally, three angular cutting edges 2 are provided, but six can also be provided.) During machining, cutting is performed through the angular cutting edge 2. It should be noted that the first half mentioned in this invention refers to the continuous feeding along the center line C from the end of the angular cutting edge 2 (i.e., the intersection of the two cutting edges 21 and 22), with the part from the intersection 20 of the two cutting edges 20 to the middle position of the cutting edges participating in the machining. The second half refers to the machining of most or all of the two cutting edges 21 and 22 of the angular cutting edge 2. Therefore, the cutting surface is large and the cutting resistance is large during the second half of the machining.

[0038] In this embodiment, the insert body 1 covers 3 corner cutting edges 2 for participating in cutting. Under normal circumstances, it covers 1-6 corner cutting edges 2. In thread machining, it is locked by a center hole screw (not shown in the figure) for machining. Then, after one corner cutting edge 2 fails, it is rotated through the center to another corner cutting edge 2 for machining.

[0039] The corner cutting edge 2 is connected to the side walls 12, 13, and 14 on the three bodies 1 through the finishing edge 10 (it should be noted that in this invention, the outer edge 11 of the body 1 includes the side walls 12, 13, and 14 of the body 1 and the finishing edge 10); the side walls 12, 13, and 14 of the body 1 are generally used for positioning in conjunction with the tool holder; and the lower surface of the body 1 and the side walls 12, 13, and 14 have chamfers, so as to prevent the edge at the junction of the bottom and the side wall from preferentially contacting the positioning surface during positioning, resulting in the inability to contact the entire positioning surface, thereby affecting the positioning stability.

[0040] The corner cutting edge 2 includes two cutting edges 21 and 22 (i.e., cutting edges) that participate in the machining. The two cutting edges 21 and 22 are set at an acute angle (generally 30°, 55° or 60°, and the intersection position 20 of the two cutting edges can be connected by a circular arc, a straight line plus a circular arc or a straight line plus a chamfer, depending on the different tooth profile standards). The two cutting edges 21 and 22 are connected to the outer edge 11 of the body 1 through a curved surface transition. The outer edge 11 of the body 1 is configured as a finishing edge 10 to perform fine finishing on the surface of the thread groove, improve the surface quality of the workpiece, reduce burrs and achieve accurate thread major diameter.

[0041] A cutting center line C is defined in the middle of the corner cutting edge 2, which is set parallel to the outer edge 11 of the body (here, the outer edge 11 of the body 1 refers to the edge of the side wall 12, 13, 14 of the body 1, not the position of the finishing edge 10); it should be noted that, under normal circumstances, the cutting center line C is parallel to the outer edge 11 of the body, but the cutting center line C of some non-standard inserts is not parallel to the outer edge 11 of the body.

[0042] Please refer to this as well. Figure 4 and Figure 5 On the upper surface of the body 1, the two cutting edges 21 and 22 of the angular cutting edge 2 are offset inward along the cutting center line C, and a front cutting surface 3, a chip groove 4 and a first protrusion 5 are formed in sequence; the front cutting surface 3, the chip groove 4 and the first protrusion 5 are arranged symmetrically with respect to the cutting center line C.

[0043] Among them, the front cutting edge 3 and the chip groove 4 are inclined inward along the cutting edge center line C and towards the lower surface of the body 1 at a certain angle. Such inclination allows the chips to flow smoothly to the chip groove 4 and the first protrusion 5.

[0044] The chip groove 4 has a trapezoidal cross-section along the center line C of the cutting edge, and the bottom 41 of the chip groove 4 is arranged downward from the intersection 20 of the two cutting edges 21 and 22 towards the first protrusion 5; in addition, the surface in the chip groove 4 that is in contact with the front cutting edge 3 is configured as an adjacent surface 42, and the adjacent surface 42 is inclined; thus, during the machining process, the chips can smoothly enter the chip groove 4 along the adjacent surface 42 and be guided to control the chip movement trajectory.

[0045] It should also be noted that the transverse cross-section of the chip groove 4 of the present invention is approximately triangular or trapezoidal. The transverse cross-section refers to the cross-section parallel to the lower surface of the blade body 1, which can also be understood as the cross-section viewed from a top angle (i.e., Figure 2 (From an angle) looking at the chip groove 4, the chip groove 4 is triangular in shape; this structural design allows the chip to flow more smoothly into the chip groove 4 as the cutting area increases from the first half to the second half of the thread machining; in addition, the depth of the chip groove 4 is generally designed to be 0.02-0.2mm, and the distance h from the edge of the adjacent surface 42 to the intersection position 20 of the two cutting edges is generally designed to be 0.1-0.5mm. This not only helps to control the shrinkage of the chips, ensure the sharpness of the cutting edge, reduce the cutting force, and reduce machining vibration, but also reduces the friction between the chips and the rake face, reduces the wear of the crater, and ensures that the chips can be effectively transferred to the rear in the second half of the thread machining. On the other hand, it is conducive to the storage and flow of coolant to remove more heat, resulting in better cooling effect;

[0046] Please refer to Figure 4 and Figure 5 The first protrusion 5 extends upward at the lowest position 51 of the chip groove 4 and forms at least one straight section 53 at a position above the front cutting edge 3 so that the cutting chip moves along the straight section 53.

[0047] It should be noted that in this invention, the chip-guiding surface of the first protrusion 5 extends in a streamlined, inclined manner towards the interior of the body 1 along the center line C of the cutting edge, like the slope of a mountain ridge, and forms a sequentially connected transition arc section 52, the straight section 53, the inlet section 54, and the end extension section 55; here, "streamlined" means that the transition arc section 52, the straight section 53, the inlet section 54, and the end extension section 55 are sequentially connected, and in the cross-sectional state, the connecting lines of each section 52, 53, 54, and 55 smoothly transition from low to high, such as... Figure 5 As shown;

[0048] The transition arc section 52 is smoothly connected to the chip groove 4 (the transition arc section 52 here is a concave arc surface, thus ensuring smooth chip flow); the straight section 53 is located between the transition arc section 52 and the guide section 54 (in this embodiment, the angle γ between the straight section 53 and the upper surface of the body 1 is in the range of 10-35°), which is beneficial for the chip groove to flow from the transition arc section 52 to the straight section 53, further achieving the effect of chip rolling; the guide section 54 has an arc and is adjacent to the end extension section 55 (the arc of the guide section 54 here is an outward convex arc with a short distance, used to be adjacent to the end extension section 55).

[0049] Furthermore, the two cutting edges 21 and 22 of the angle cutting edge 2 are connected to the finishing edge 10 via an arc surface transition, and the distance from this arc surface to the first protrusion 5 is less than the distance from the intersection of the two cutting edges 20 to the first protrusion 5. During the latter half of the machining process, the chips from the two cutting edges 21 and 22 of the angle cutting edge and the arc surface transition position connected to the finishing edge 10 can flow to the first protrusion 5 more quickly, ensuring that the rear part of the chip curls. The chips from the intersection of the two cutting edges 20 pass through the chip groove 4 and then to the first protrusion 5. This effectively reduces the cutting force. This design can effectively solve the problem of high cutting force and difficulty in chip breaking and removal in the latter half of thread machining.

[0050] In addition, the body 1 is provided with at least two second protrusions 6, which are symmetrically arranged on both sides of the first protrusion 5 with respect to the blade center line C; the convex surfaces 61 on the two second protrusions 6 for chip swirling are inclined toward the intersection position 20 of the two blades (in this embodiment, the angle between the two second protrusions 6 and the blade center line C is in the range of 70-85°), so that the chips gather toward the intersection position 20 of the two blades; moreover, the highest position of the second protrusion 6 is lower than the highest position of the end extension 55 and higher than the lowest position 51 of the end extension 55, so that the chip direction is closer to the blade center line C.

[0051] In this invention, the main body 1 is further provided with a chip guide protrusion 7, which is disposed on the side of the second protrusion 6 and has a height greater than that of the second protrusion 6. The chip guide protrusion 7 plays a secondary protection role, that is, it ensures that the chips that flow out from the second protrusion 6 without control are restricted at the position of the chip guide protrusion 7, thereby playing a chip control role.

[0052] In actual thread machining process:

[0053] (1) Fix the body 1 of the thread insert to the tool holder (not shown in the figure) with screws, and make one corner of the cutting edge 2 face outward and correspond to the workpiece to be processed;

[0054] (2) The workpiece to be processed rotates and moves relative to the thread insert, and comes into contact with the corner cutting edge 2;

[0055] (3) During the cutting process, the first half (first half section) is processed first, that is, the two cutting edges of the corner cutting edge 2 intersect at the position 20. The cutting chips move inward from the front cutting edge 3 along the inclined direction, and then enter the chip groove 4 with a cross-section similar to a triangle. After passing the adjacent surface 42 and the bottom 41 of the chip groove 4, they move upward from the other side of the chip groove 4 and move upward from the chip guide surface of the first protrusion 5 and curl up. It is explained here that during the movement, after passing through the transition arc section 52 of the chip guide surface, the chips flow upward from the straight section 53 to the inlet section 54 and curl up until the chips break.

[0056] As the depth of the thread groove increases, the cutting edges 21 and 22 on both sides also participate in the cutting. As the cutting area gradually increases, the cutting resistance increases. At this time, the cutting, chip rolling and chip breaking are still in the above state until the latter half of the process is completed.

[0057] During the latter half of the machining process, due to the increased cutting area, the chips at the intersection of the two cutting edges 20 still curl up. The chips generated by the cutting edges 21 and 22 near the finishing edge 10, due to their short distance from the first protrusion 5, move rapidly from the front cutting surface 3 to the transition arc section 52 of the first protrusion 5, and then displace through the straight section 53. Simultaneously, the curled chips are confined by the second protrusions 6 on both sides of the first protrusion 5, causing them to converge towards the cutting edge centerline C. It should be noted that the chips from the transition arc section 52, through the extension of the straight section 53, during the latter half of the machining process, cause the two cutting edges 21 and 22 of the corner cutting edge to... The chips at the arc transition position connected to the finishing blade 10 at point 22 can flow to the first protrusion 5 quickly, ensuring that the rear part of the chip curls. The chips at the intersection of the two blades 20 pass through the chip groove 4 and then to the first protrusion 5, which can effectively reduce the cutting force. This design can effectively solve the problem of large cutting force and difficult chip breaking and removal in the second half of thread machining. Moreover, the chip curling position is delayed, so the chip curling position is rearward. That is to say, the chip has enough space to move backward and flow or move smoothly, thereby reducing the cutting force. Combined with effective control of the chip curling direction, the chip curling and chip removal effect is greatly improved.

[0058] Furthermore, the secondary guidance of the chip guide protrusion 7 prevents chips from flowing onto the machined surface.

[0059] The description of the above specification and embodiments is used to explain the scope of protection of the present invention, but does not constitute a limitation on the scope of protection of the present invention.

Claims

1. A thread turning insert, comprising a body and an angular cutting edge formed on the outer edge of the body and adapted to a thread groove, the angular cutting edge having a center line; characterized in that: On the upper surface of the body, the two cutting edges of the angular cutting edge are offset inward along the center line of the cutting edge, and a front cutting surface, a chip groove, and a first protrusion are formed in sequence. The front cutting surface and the chip groove are inclined at a certain angle inward along the center line of the cutting edge and toward the lower surface of the body. The cross section of the chip groove along the center line of the cutting edge is trapezoidal, and the bottom of the chip groove is arranged downward from near the intersection of the two cutting edges toward the first protrusion. The transverse cross section of the chip groove is triangular or trapezoidal. The first protrusion extends upward from the lowest position of the chip groove and forms at least one straight section above the front cutting surface so that the chip moves along the straight section. The first protrusion also forms a transition arc section that is smoothly connected to the chip groove. The transition arc section is a concave arc surface.

2. The thread turning insert as described in claim 1, characterized in that: The two cutting edges of the angle cutting edge are respectively connected to the outer edge of the body via an arc surface transition, and the distance from the arc surface to the first protrusion is less than the distance from the intersection of the two cutting edges to the first protrusion.

3. A thread turning insert as described in claim 1, characterized in that: The surface within the chip groove that is in contact with the front cutting edge is configured as an adjacent surface, and the adjacent surface is inclined.

4. A thread turning insert as described in claim 3, characterized in that: The depth of the chip groove is 0.02-0.2 mm, and the distance from the edge of the adjacent surface to the intersection of the two cutting edges is 0.1-0.5 mm.

5. A thread turning insert as described in claim 3, characterized in that: The chip-guiding surface of the first protrusion extends in a streamlined inclination towards the interior of the body along the center line of the cutting edge, and forms the transition arc section, the straight section, the inlet section and the end extension section connected in sequence; the straight section is located between the transition arc section and the inlet section; the inlet section has an arc and borders the end extension section.

6. A thread turning insert as described in claim 5, characterized in that: The body is also provided with at least two second protrusions, which are symmetrically arranged on both sides of the first protrusion with respect to the center line of the blade; the convex surfaces of the two second protrusions for shredding are inclined toward the intersection of the two blades and are set at an acute angle to the center line of the blade, so that the shredding gathers toward the intersection of the two blades.

7. A thread turning insert as described in claim 6, characterized in that: The highest position of the second protrusion is lower than the highest position of the end extension and higher than the lowest position of the end extension.

8. A thread turning insert as described in claim 7, characterized in that: The body is also provided with a chip guide protrusion, which is located on the side of the second protrusion and has a height greater than that of the second protrusion.

9. A thread turning insert as described in claim 1, characterized in that: The angle between the straight section and the upper surface of the body ranges from 10° to 35°.

Images