A bolt capable of secure fixing

Abstract

The utility model relates to mechanical connecting component technical field, the utility model discloses a kind of bolt that can be fixed stably, it includes: one end is equipped with taper slot, slot width is reduced along screw inside, screw, adaptation slot, extruding piece is connected to groove wall in middle part by easy breaking connecting piece, protrude in groove opening inner wall, prevent extruding piece from separating screw limiting portion, inclined radial through-hole, adaptation through-hole, one end has pressure-bearing part, one end is slightly larger hole outer end rough end, outer periphery is equipped with the positioning protrusion of fixed rod and the positioning recess of through-hole inner wall.Screw advances rotation, extruding piece is pressed and moves inwards to make connecting piece break, then extruding pressure-bearing part drives fixed rod to move outwards, until positioning protrusion and positioning recess are connected and fixed.The utility model bolt is strong, and taper slot and inverted round table extruding piece are uniformly power transmission, drive fixed rod to move outwards;Positioning protrusion is connected and limited, anti-skid end increases resistance, 2-4 uniform through-hole makes stress balance, forms multiple fixing, long-term anti-vibration and anti-loose.

Description

Technical Field

[0001] This utility model relates to the field of mechanical connection components, and in particular to a bolt that can be securely fixed. Background Technology

[0002] In mechanical connections, equipment installation, and building fastening, bolts, as connecting components, directly affect the safety and service life of the overall structure due to their stability. Currently, most common bolts rely on the friction between the threads and the mounting surface for fixation. However, under long-term vibration, external impact, or temperature changes, the friction between the threads gradually weakens, leading to bolt loosening or even detachment. This not only affects the normal operation of equipment but may also pose safety hazards. While some improved bolt designs attempt to add anti-slip washers and elastic washers, these designs only improve anti-slip performance in the short term and cannot fundamentally solve the bolt displacement problem. Furthermore, the addition of extra accessories increases installation steps and costs, and in complex installation environments, accessories are prone to being lost or improperly installed, reducing the reliability of the fixation.

[0003] Existing bolts with multi-directional fixing functions have significant defects in structural design and operational practicality. Some bolts lack precise triggering and limiting mechanisms in their radial fixing components. This leads to either an unreasonable fixing rod drive structure, resulting in uneven extension or unstable clamping; or a lack of reliable component constraint structures, such as the clamping component easily detaching from its preset position during early installation; or poor compatibility between the fixing rod and the through hole, causing problems like movement jamming and positioning misalignment. Furthermore, most multi-directional fixing bolts have poor adaptability, unable to flexibly adjust the fixing position according to different installation depths. The unreasonable design of the number and distribution of components such as radial through holes and fixing rods easily causes uneven stress on the bolt and installation position, leading to localized stress concentration that can damage the installation position or deform the bolt. This makes it difficult to meet the dual requirements of stability and adaptability in diverse scenarios. Utility Model Content

[0004] To address the shortcomings of existing technologies, this utility model discloses a bolt that can securely fix the object and is easy to operate.

[0005] This utility model discloses a bolt capable of secure fixing, comprising:

[0006] The nut and the screw connected to the nut, one end of the screw is provided with a tapered groove, the width of the tapered groove gradually decreases along the inside of the screw;

[0007] The extrusion part is adapted to be disposed in the conical groove. The middle part of the extrusion part is fixedly connected to the inner wall of the conical groove through a easily breakable connector. The side of the extrusion part near the opening of the conical groove is provided with an outwardly protruding extrusion limiting part.

[0008] The screw limiting part protrudes from the inner wall of the screw near the opening of the tapered groove;

[0009] At least one radial through hole, the radial through hole obliquely penetrating the inner wall of the tapered groove opening;

[0010] A fixing rod is adapted to pass through a radial through hole, and the outer diameter of the fixing rod is adapted to the inner diameter of the radial through hole;

[0011] The pressure-bearing part is located at one end of the fixed rod near the inside of the screw;

[0012] A rough fixing part is provided at the end of the fixing rod away from the pressure bearing part, and the size of the rough fixing part is larger than the outer end opening size of the radial through hole;

[0013] At least one positioning protrusion is provided on the outer peripheral surface of the fixing rod;

[0014] Several positioning grooves are recessed into the inner wall of the radial through hole;

[0015] When the screw is pushed into the mounting position and rotates, the extrusion part is squeezed into the screw by the inner wall of the conical groove, causing the easily broken connecting part to break. After the extrusion part is separated from the fixed part, it squeezes the pressure bearing part and drives the fixed rod to move outward along the radial through hole until the positioning protrusion and positioning groove are engaged and fixed.

[0016] Furthermore, the extruded part has an inverted frustum structure, and its outer circumferential surface is adapted to the inner wall of the conical groove.

[0017] Furthermore, the easily breakable connectors are made of brittle materials or low-strength plastics.

[0018] Furthermore, the number of radial through holes is 2-4, and they are evenly distributed along the circumference of the tapered groove opening. The number of fixing rods is adapted to the radial through holes and they are respectively set in the radial through holes.

[0019] Furthermore, the number of positioning protrusions is 2-3, and they are spaced apart along the circumference of the fixing rod;

[0020] The number of positioning grooves matches the number of positioning protrusions, and they are distributed at axial intervals along the radial through holes.

[0021] Furthermore, the surface of the rough fixing part is provided with anti-slip texture or granular protrusions.

[0022] Furthermore, the screw limiting part is an annular flange, the inner diameter of which is smaller than the outer diameter of the extruded part near the opening of the conical groove.

[0023] Furthermore, the radial through hole is inclined in the following direction: from the inner sidewall of the tapered groove opening towards the outside of the screw, and its axis forms an angle of 30°-75° with the screw axis.

[0024] Beneficial effects:

[0025] The advantages of this utility model bolt lie in its significantly improved fixing stability, ensuring a reliable connection over a long period. Through the matching structure of the conical groove and the inverted frustum extrusion component, the extrusion component can evenly transmit force when pushed, driving the fixing rod to move outward along the radial through-hole. The precise engagement of the positioning protrusion and the groove restricts the axial and circumferential displacement of the fixing rod, while the anti-slip texture or particle protrusions on the rough fixing part further increase friction with the mounting position. Two to four radially distributed through-holes and corresponding fixing rods ensure balanced force on the bolt and mounting position, preventing loosening caused by localized stress concentration. This forms a multi-layered fixing system of extrusion drive, engagement limiting, and anti-slip resistance, maintaining a stable connection even under long-term vibration or external force.

[0026] This utility model's bolt installation process combines precision and reliability, effectively reducing operational error-tolerance costs. The easily breakable connector uses brittle materials or low-strength plastic parts, precisely breaking only when the extrusion part reaches a preset force. This prevents installation chaos caused by premature failure and avoids excessive strength hindering the fixing action. The annular flange screw limiting part always restricts the extrusion part from detaching from the conical groove opening, ensuring its movement along a preset trajectory. The radial through-hole's 30°-75° included angle design balances the moving resistance of the fixing rod with structural stability, preventing jamming and offset affecting the locking mechanism. Multiple fixing rods move synchronously, ensuring an orderly installation process and achieving reliable fixing without complex operations.

[0027] This utility model bolt possesses excellent adaptability and practicality, suitable for various installation scenarios and easy to manufacture. The positioning grooves are axially spaced along the radial through holes, allowing for flexible adjustment of the fixing rod's snap-fit ​​position according to the installation depth, eliminating the need for strict alignment of a single point. The rough fixing part structure adapts to installation locations of different materials, enhancing its applicability. The design of 2-4 radial through holes satisfies the need for stability while avoiding the processing complexity and structural redundancy caused by an excessive number of holes. The overall structure balances functionality and ease of production, improving the fixing effect while reducing manufacturing and installation costs, thus possessing high practical value. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of one type of bolt in an embodiment of this application.

[0029] Figure 2 This is a cross-sectional structural diagram of a bolt in one embodiment of this application.

[0030] Figure 3 for Figure 2 Enlarged view of point A in the middle.

[0031] In the figure: Bolt 100, Nut 11, Screw 12, Extrusion part 13, Easily breakable connector 131, Extrusion limiting part 132, Screw limiting part 14, Fixing rod 15, Pressure bearing part 16, Rough fixing part 17, Positioning protrusion 18. Detailed Implementation

[0032] To enable those skilled in the art to better understand the present invention, the technical solutions in the specific embodiments of the present invention will be clearly and completely described below.

[0033] This utility model discloses a bolt 100 that can securely fix the object, such as... Figure 1 As shown, it includes: a nut 11 and a screw 12 connected to the nut 11, one end of the screw 12 having a tapered groove, the width of which gradually decreases along the inner direction of the screw 12; and an extrusion member 13, which is adapted to be disposed within the tapered groove, the middle part of which is fixedly connected to the inner wall of the tapered groove via a breakable connector 131, such as... Figure 2 As shown, the extruder 13 has an outwardly protruding extrusion limiting part 132 near the opening of the conical groove. A screw limiting part 14 protrudes from the inner wall of the screw 12 near the opening of the conical groove, used to prevent the extruder 13 from disengaging from the opening of the conical groove. At least one radial through hole obliquely penetrates the inner wall of the opening of the conical groove. A fixing rod 15, as shown... Figure 3 As shown, the fixing rod 15 is adapted to pass through the radial through hole, and the outer diameter of the fixing rod 15 matches the inner diameter of the radial through hole. A pressure-bearing portion 16 is located at one end of the fixing rod 15 near the interior of the screw 12, and is used to cooperate with the extruder 13 to increase the extrusion contact area. A roughening fixing portion 17 is located at one end of the fixing rod 15 away from the pressure-bearing portion 16, and the size of the roughening fixing portion 17 is larger than the outer opening size of the radial through hole. At least one positioning protrusion 18 protrudes from the outer peripheral surface of the fixing rod 15. Several positioning grooves are recessed into the inner wall of the radial through hole, and are used to engage with the positioning protrusion 18 to fix the fixing rod 15 when it is compressed and moved. When the screw 12 is pushed into the mounting position and rotates, the extrusion member 13 is pressed into the screw 12 by the inner wall of the conical groove, causing the easily broken connecting member 131 to break. After the extrusion member 13 is released from the fixation, it presses the pressure bearing part 16 and drives the fixing rod 15 to move outward along the radial through hole until the positioning protrusion 18 is engaged and fixed with the positioning groove.

[0034] As the screw 12 is pushed into the mounting position and rotates, the tapered groove at one end of the screw 12 exerts a squeezing effect on the fitting extruder 13 within the groove. Since the width of the tapered groove gradually decreases along the inner direction of the screw 12, the extruder 13 is pushed into the screw 12. During this process, the fixing relationship between the middle of the extruder 13 and the inner wall of the tapered groove via the easily breakable connector 131 is disrupted, causing the easily breakable connector 131 to break. The detached extruder 13 directly acts on the pressure-bearing part 16 of the fixing rod 15 near the inner end of the screw 12. With the increased contact area of ​​the pressure-bearing part 16, the fixing rod 15 is stably driven to move outward along the radial through hole. As the fixing rod 15 moves outward, the positioning protrusion 18 on its outer circumference gradually aligns with the positioning groove on the inner wall of the radial through hole, ultimately achieving a snap-fit ​​engagement, fixing the position of the fixing rod 15, and completing the secure installation of the bolt 100. Meanwhile, the screw limiting part 14 near the inner wall of the conical groove opening of the screw 12 will always cooperate with the extrusion limiting part 132 to restrict the extruded part 13 from disengaging from the conical groove opening, ensuring that the whole process proceeds in an orderly manner.

[0035] The stability of bolt 100's fixation primarily relies on the dual-fixing design of fixing rod 15. The snap-fit ​​between the positioning protrusion 18 and the positioning groove directly restricts the axial movement of fixing rod 15, preventing it from retracting due to vibration or other factors after installation. Meanwhile, the rough fixing portion 17 at the end of fixing rod 15 away from the pressure-bearing part 16 is larger than the outer opening of the radial through hole, preventing the fixing rod 15 from completely detaching from the through hole. Its anti-slip texture or granular protrusions significantly increase the friction with the contact surface at the mounting position, enhancing the fixing effect. The radial through holes are designed to be 2-4 in number and evenly distributed circumferentially along the opening of the tapered groove. The corresponding fixing rods 15 are also evenly distributed, ensuring a more balanced force distribution between bolt 100 and the mounting position, preventing excessive localized stress that could lead to loosening, and structurally guaranteeing long-term stability.

[0036] During installation, the design of the easily breakable connector 131 ensures reliable triggering of the fixing process. Made of brittle materials or low-strength plastic, it can precisely break when the extruder 13 is compressed by the inner wall of the conical groove. This prevents the extruder 13 from becoming immobile due to excessive strength, or from breaking prematurely due to insufficient strength, ensuring the fixing action is triggered as expected. The extruder 13 adopts an inverted frustum structure, with its outer circumference perfectly fitting the inner wall of the conical groove. This allows the extruder 13 to maintain stable contact with the inner wall of the conical groove during movement, ensuring that the extrusion force is evenly transmitted to the pressure-bearing part 16, preventing the fixing rod 15 from jamming due to uneven force distribution. The screw limiting part 14 adopts an annular flange design, with its inner diameter smaller than the outer diameter of the end of the extruder 13 closest to the opening of the conical groove. This effectively prevents the extruder 13 from detaching towards the opening, providing a stable structural constraint for the entire installation process and improving the reliability of the installation operation.

[0037] In one embodiment, the extrusion part 13 is an inverted frustum structure, and its outer peripheral surface is adapted to the inner wall of the conical groove.

[0038] The extrusion member 13 adopts an inverted frustum structure, and its outer circumferential surface is adapted to the inner wall of the conical groove. This allows the extrusion member 13 to maintain full and tight contact with the inner wall of the conical groove as the screw 12 is pushed into the installation position and rotates. Since the width of the conical groove gradually decreases along the inner direction of the screw 12, this adaptation structure allows the extrusion force exerted by the inner wall of the conical groove on the extrusion member 13 to be evenly distributed on the outer circumferential surface of the extrusion member 13, avoiding localized force concentration or force imbalance due to insufficient contact. When the easily breakable connector 131 breaks, the extrusion member 13 can stably transmit the uniform extrusion force to the pressure-bearing part 16 of the fixing rod 15, ensuring that the fixing rod 15 moves smoothly and without jamming when moving outward along the radial through hole. This provides a stable power foundation for the subsequent precise engagement of the positioning protrusion 18 and the positioning groove, and avoids the fixing rod 15 from shifting due to uneven extrusion force transmission, which would affect the fixing effect.

[0039] In one embodiment, the easily breakable connector 131 is a brittle material or a low-strength plastic part.

[0040] The easily breakable connector 131 is made of brittle material or low-strength plastic, and its strength characteristics are highly compatible with the stress requirements during the installation of the bolt 100. When the screw 12 is pushed into the installation position and rotates, the inner wall of the conical groove compresses the extruder 13, causing the extruder 13 to move inward into the screw 12. At this time, the connector made of this material can break precisely when the compressive force reaches the preset value. It will not be impossible to push the extruder 13 due to excessive material strength, making it difficult to trigger the fixing action, nor will it break prematurely due to insufficient material strength, thus preventing the extruder 13 from detaching from the fixation before the initial installation is completed. This precise fracture characteristic ensures that the extruder 13 can promptly compress the pressure-bearing part 16 after detaching from the fixation, driving the fixing rod 15 to move outward along the radial through hole. This provides an accurate action trigger point for the subsequent engagement and fixation of the positioning protrusion 18 and the positioning groove, ensuring that the entire installation process proceeds in an orderly manner as expected.

[0041] In one embodiment, the number of radial through holes is 2-4, and they are evenly distributed along the circumference of the tapered groove opening. The number of fixing rods 15 is adapted to the radial through holes and they are respectively set in the radial through holes.

[0042] Two to four radial through holes are evenly distributed circumferentially along the opening of the tapered groove. Corresponding fixing rods 15 are inserted into each through hole, allowing the fixing rods 15 to move outwards from the mounting position and contact the mounting position, thus evenly transmitting the force along the circumference of the screw 12 to the inner wall of the mounting position. This uniform force-bearing structure avoids the situation where the fixing point is concentrated on one side, causing the bolt 100 to experience excessive local stress, tilting, or loosening during long-term use due to vibration, external forces, etc. At the same time, the multiple evenly distributed fixing rods 15, together with their respective rough fixing parts 17, can form a stable frictional constraint from multiple points around the screw 12, further enhancing the connection between the bolt 100 and the mounting position. Together with the tapered groove, the extrusion part 13, and other structures, this ensures the stable fixing effect of the bolt 100. The number of fixing rods 15 is matched with the radial through holes, and the through holes are evenly distributed. This ensures that when the screw 12 is pushed into the installation position and rotates, the extrusion force of the extrusion member 13 after it is disengaged from the fixing is transmitted synchronously to each bearing part 16. This makes the moving speed and distance of all fixing rods 15 along their respective radial through holes consistent. In this way, the positioning protrusions 18 of each fixing rod 15 can be synchronously engaged and fixed with the positioning grooves on the inner wall of the corresponding radial through hole. This avoids the situation where some fixing rods 15 are not locked or some are over-extruded, thus improving the reliability of the installation process.

[0043] In one implementation, there are 2-3 positioning protrusions 18, which are spaced apart circumferentially along the fixing rod 15;

[0044] The number of positioning grooves is adapted to the positioning protrusions 18, and they are distributed at axial intervals along the radial through holes.

[0045] Two to three positioning protrusions 18 are spaced circumferentially along the fixing rod 15. These, along with appropriately spaced positioning grooves axially spaced along the radial through-hole, allow the fixing rod 15 to engage at multiple points when it moves outward along the radial through-hole under pressure. This multi-point engagement structure evenly distributes the force on the fixing rod 15 across the contact points of different protrusions and grooves, preventing wear or detachment at a single contact point due to excessive force. This prevents axial or circumferential displacement of the fixing rod 15 after installation due to vibration, external forces, or other factors. The axially spaced positioning grooves along the radial through-hole allow the fixing rod 15 to engage with the positioning protrusions 18 at different axial positions during movement, depending on the actual depth of the installation location or the magnitude of the compressive force. This eliminates the need for strict alignment of a single fixing point, effectively accommodating minor dimensional deviations that may occur during installation and reducing the precision requirements of the installation operation. The design of 2-3 positioning protrusions 18 avoids both the problem of insufficient engagement stability caused by too few protrusions and the problem of increased processing difficulty and the possibility of the overall fixing effect being affected by the poor engagement of a single protrusion. This structure, together with the design of evenly distributed radial through holes and synchronous movement of fixing rods 15, ensures that each fixing rod 15 can be successfully engaged, improving the reliability and fault tolerance of bolt 100 installation operations.

[0046] In one embodiment, the surface of the rough fixing part 17 is provided with anti-slip texture or granular protrusions.

[0047] The anti-slip texture or granular protrusions on the surface of the roughened fixing part 17 increase the contact friction between the fixing rod 15 and the inner wall of the mounting position. When the fixing rod 15 is pressed and moves outward along the radial through hole and fits against the mounting position, the anti-slip texture or granular protrusions can form a tight frictional engagement with the surface of the mounting position, effectively preventing the fixing rod 15 from sliding due to vibration, external disturbance, etc. during subsequent use. At the same time, combined with the design that the size of the roughened fixing part 17 is larger than the outer opening of the radial through hole, it can not only prevent the fixing rod 15 from completely disengaging from the radial through hole, but also further enhance the connection strength between the fixing rod 15 and the mounting position through the anti-slip texture or granular protrusions, and enhance the overall stability of the fixing bolt 100 by the snap-fit ​​fixing of the positioning protrusion 18 and the positioning groove.

[0048] In one embodiment, the screw limiting part 14 is an annular flange, the inner diameter of which is smaller than the outer diameter of the extruder 13 near the opening of the conical groove.

[0049] The screw limiting part 14 is designed as an annular flange with an inner diameter smaller than the outer diameter of the end of the extrusion part 13 near the opening of the conical groove, forming a full-circumferential constraint boundary from the inside of the conical groove opening. During the transportation and early installation of the bolt 100, or during the process of the extrusion part 13 being squeezed and moved by the inner wall of the conical groove, the annular flange can completely block the extrusion part 13 from moving towards the opening of the conical groove, thus completely preventing the extrusion part 13 from detaching from the opening. This design, combined with the fixing effect of the easily breakable connector 131 on the extrusion part 13, ensures that the extrusion part 13 is always stably positioned in the preset position within the conical groove. This ensures that when the screw 12 is subsequently pushed and rotated, the extrusion part 13 can be smoothly squeezed and broken by the connector and the pressure-bearing part 16, providing a basic guarantee for the movement and locking of the fixing rod 15, and preventing the failure of the entire fixing structure due to the extrusion part 13 falling off.

[0050] In one embodiment, the radial through hole is inclined in the direction of inclination from the inner sidewall of the tapered groove opening toward the outside of the screw 12, and its axis forms an angle of 30°-75° with the axis of the screw 12.

[0051] The through hole is inclined from the inner wall of the tapered groove opening outwards towards the screw 12, with its axis forming an angle of 30°-75° with the axis of the screw 12. This inclination direction guides the rough fixing part 17 of the fixing rod 15 to extend at an angle that is closer to the inner wall of the mounting position when it moves along the through hole, away from the pressure bearing part 16. This angle ensures that the fixing rod 15 has sufficient outward extension length to penetrate the mounting position and form effective support, while avoiding a reduction in the contact area between the end of the fixing rod 15 and the mounting position due to an excessively large inclination angle, or an insufficient extension of the fixing rod 15 due to an excessively small angle, resulting in inadequate locking. At the same time, the inclination direction matches the direction of the extrusion force of the tapered groove extruder 13 moving inwards towards the screw 12, allowing the thrust of the extruder 13 on the pressure bearing part 16 to be more smoothly converted into the outward movement force of the fixing rod 15 along the through hole, making the rough fixing part 17 tightly abut against the mounting position. Combined with its anti-slip structure, this further enhances the connection strength between the bolt 100 and the mounting position.

[0052] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A bolt capable of secure fixing, characterized in that, include: The nut and the screw connected to the nut, one end of the screw is provided with a tapered groove, the width of the tapered groove gradually decreases along the inside of the screw; The extrusion part is adapted to be disposed in the conical groove. The middle part of the extrusion part is fixedly connected to the inner wall of the conical groove through a easily breakable connector. The side of the extrusion part near the opening of the conical groove is provided with an outwardly protruding extrusion limiting part. The screw limiting part protrudes from the inner wall of the screw near the opening of the tapered groove; At least one radial through hole, the radial through hole obliquely penetrating the inner wall of the tapered groove opening; A fixing rod is adapted to pass through a radial through hole, and the outer diameter of the fixing rod is adapted to the inner diameter of the radial through hole; The pressure-bearing part is located at one end of the fixed rod near the inside of the screw; A rough fixing part is provided at the end of the fixing rod away from the pressure bearing part, and the size of the rough fixing part is larger than the outer end opening size of the radial through hole; At least one positioning protrusion is provided on the outer peripheral surface of the fixing rod; Several positioning grooves are recessed into the inner wall of the radial through hole; When the screw is pushed into the mounting position and rotates, the extrusion part is squeezed into the screw by the inner wall of the conical groove, causing the easily broken connecting part to break. After the extrusion part is separated from the fixed part, it squeezes the pressure bearing part and drives the fixed rod to move outward along the radial through hole until the positioning protrusion and positioning groove are engaged and fixed.

2. The bolt capable of secure fixing according to claim 1, characterized in that: The extruded part has an inverted frustum structure, and its outer circumferential surface is adapted to the inner wall of the conical groove.

3. The bolt capable of secure fixing according to claim 1, characterized in that: Easily breakable connectors are made of brittle materials or low-strength plastics.

4. A bolt capable of secure fixing according to claim 1, characterized in that: The number of radial through holes is 2-4, and they are evenly distributed along the circumference of the tapered groove opening. The number of fixing rods is matched with the number of radial through holes and they are respectively set in the radial through holes.

5. A bolt capable of secure fixing according to claim 1, characterized in that: There are 2-3 positioning protrusions, which are spaced apart circumferentially along the fixing rod; The number of positioning grooves matches the number of positioning protrusions, and they are distributed at axial intervals along the radial through holes.

6. A bolt capable of secure fixing according to claim 1, characterized in that: The surface of the rough fixing part is provided with anti-slip texture or granular protrusions.

7. A bolt capable of secure fixing according to claim 1, characterized in that: The screw limiting part is an annular flange, the inner diameter of which is smaller than the outer diameter of the end of the extruded part near the opening of the conical groove.

8. A bolt capable of secure fixing according to claim 1, characterized in that: The radial through hole is inclined from the inner wall of the tapered groove opening to the outside of the screw, and its axis forms an angle of 30°-75° with the screw axis.

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