Novel flow drill screw and rotary friction connection method thereof

Abstract

The invention discloses a novel flow drill screw and a rotating friction connection method thereof, and relates to the technical field of screw connection, the novel flow drill screw comprises a drill rod, a screw drill sleeve arranged on the drill rod in a sleeving mode and a brazing filler metal cylinder, the screw drill sleeve is of a hollow structure and is in clearance fit with the drill rod, and a plurality of round holes are formed in the screw drill sleeve and used for installing the brazing filler metal cylinder; the annular protrusion on the drill rod is matched with the first annular groove, the second annular groove and the third annular groove in the screw drill sleeve to form a mortise and tenon joint structure. In the connecting process, the drill rod is pulled upwards, the cone on the lower portion of the drill rod extrudes the tail of the screw drill sleeve to enable the open groove to be opened, the opened open groove and the end of the drill sleeve form a mechanical interlocking structure, a workpiece can be locked, and connection of high-strength plates is achieved. In addition, the connection strength and the connection reliability can be further improved through a mortise and tenon joint structure formed by combining the annular groove in the screw drill sleeve and the annular protrusion of the drill rod.

Description

Technical Field

[0001] The invention relates to the technical field of screw connection, and in particular to a novel flow drill screw and a rotation friction connection method thereof. Background Art

[0002] The flow drill screw connection technology is also called hot melt self-tapping connection technology. It uses a high-speed rotating screw to heat the metal sheet under a certain pressure, causing the metal sheet to soften locally. Finally, the screw penetrates the metal sheet and taps to form a threaded fastening connection. This technology can achieve unilateral connection with small deformation. Flow drill screws can complete the connection of the same and different materials. At present, it has been applied to the steel-aluminum hybrid body frame structure, such as the connection of aluminum workpiece materials, composite materials and other components with high-strength steel plates, which can achieve lightweight and high strength of the body structure.

[0003] The Chinese invention patent with publication number CN115143177B discloses a flow drill screw and a fastening device thereof. The flow drill screw has an inner through hole that penetrates the nut and the screw along the axial direction. The inner through hole allows an external high-power heat source to be input and reach the surface of the workpiece. The simplified tail cone structure of the flow drill screw shortens the length of the flow drill screw. However, the flow drill screw has no anti-loosening structure, and the connected workpiece is prone to loosening under long-term cyclic load.

[0004] The Chinese invention patent with publication number CN108799291A discloses a hot melt drill rivet and a drill rivet connection method, wherein the hot melt drill rivet comprises a core rod and a nail cap, wherein the head of the core rod is used to drill holes in the connected workpieces, and the nail cap is used to rivet the connected workpieces. The method mainly uses the core rod to complete the drilling, and uses the compression or expansion of the nail cap to form a compressed workpiece. There is a certain gap between the nail cap and the workpiece material, and a tight connection cannot be achieved.

[0005] The Chinese invention patent with publication number CN117605746A discloses a hot melt drill rivet for connecting thermoplastic composite materials and metals, which is composed of a core rod and a nail sleeve sleeved on the core rod. During the riveting process, the lower rivet section can be compressed into a drum shape to form a lower rivet cap, which together with the nail cap locks the riveted workpiece. This structure also has some shortcomings. First, the hollow tail of the shaft rod is cylindrical and has a blind hole. The shaft rod is not conducive to drilling into the material of the connected workpiece. When the blind hole is filled with the connecting material, it will be more difficult for the shaft rod to continue to drill into the lower material, especially when the lower workpiece material is a high-strength plate or other material. Secondly, the patent has an interference fit between the through hole of the shaft rod and the nail sleeve. Under the action of external tension, before the nail sleeve forms a rivet cap, the shaft rod is easy to break at the breakpoint ring groove.

[0006] In engineering applications, the connection of workpieces made of different materials, especially some high-strength plates, has higher requirements for flow drill screws and higher connection strength. The existing flow drill screw structure cannot meet the needs. Summary of the invention

[0007] The invention aims to solve the problem that the existing flow drill screws cannot achieve mechanical interlocking and high-strength connection when connecting high-strength plates.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A new type of flow drill screw, comprising a drill rod, a screw drill sleeve sleeved on the drill rod and a brazing material cylinder, wherein the screw drill sleeve is a hollow structure and forms a clearance fit with the drill rod, and a plurality of round holes are opened on the screw drill sleeve for installing the brazing material cylinder;

[0010] The annular protrusion on the drill rod cooperates with the annular groove 1, the annular groove 2 and the annular groove 3 on the screw drill sleeve to form a mortise and tenon structure.

[0011] As a further solution of the present invention: the drill rod includes a drill rod top, an annular groove, an annular protrusion, a triangular cross rib, a drill rod thread and a cone, the cone is located at the bottom of the drill rod, the drill rod thread is located at the upper part of the cone, and the triangular cross ribs are symmetrically distributed and are used to cooperate with the screw drill sleeve to transmit torque, so that the drill rod and the screw drill sleeve rotate synchronously.

[0012] As a further solution of the present invention, an annular groove is provided on the top of the drill rod. During the connection process, the drill rod is pulled off from the annular groove, and the top of the drill rod falls off, thus completing the connection.

[0013] As a further solution of the present invention: the screw drill sleeve includes a drill sleeve end, a drill sleeve end groove is provided on the drill sleeve end, the drill sleeve end groove is used to store the extruded workpiece material, a drill sleeve thread is provided on the outside of the drill sleeve end, the drill sleeve thread size is consistent with the drill rod thread size, and the length of the drill sleeve thread section is greater than the thickness of the connected workpiece.

[0014] As a further solution of the present invention: the inner surface of the screw drill sleeve is provided with a micro texture, and annular groove three, annular groove two, annular groove one and a positioning annular groove are sequentially provided below the micro texture.

[0015] As a further solution of the present invention: an open groove is provided at the lower part of the screw drill sleeve, and the open grooves are symmetrically distributed to form a small gap fit with the triangular transverse ribs on the drill rod.

[0016] As a further solution of the present invention: the drill rod and the screw drill sleeve are respectively made of different materials; the drill rod is made of high wear-resistant material, and the screw drill sleeve is made of carbon steel material.

[0017] As a further solution of the present invention: a novel method for rotating friction connection of flow drill screws, comprising the following steps:

[0018] Step 1: Assemble the brazing material cylinder, drill rod and screw drill sleeve, install the annular protrusion of the drill rod to fit the annular groove at the bottom of the screw drill sleeve, and then use the installation tool to place the flow drill screw on the surface of the workpiece to be processed;

[0019] Step 2: Start the installation tool. The installation tool drives the flow drill screw to rotate at high speed and feed along the axial direction. The cone of the drill rod rubs against the workpiece material to generate a large amount of heat, which softens the workpiece material. The cone continuously drills into the connected workpiece.

[0020] Step 3: As the cone is continuously drilled, the screw drill sleeve is also drilled into the connected workpiece. As the drilling distance increases, the flow drill screw penetrates the connected workpiece until the lower surface of the drill sleeve end contacts the upper surface of the connected workpiece, and the overflowed plastic material is squeezed into the groove at the end of the drill sleeve;

[0021] Step 4: Pull the drill rod upwards by using the installation tool to make the drill rod and the screw drill sleeve relatively displaced, and the annular protrusion of the drill rod is separated from the positioning annular groove and enters the first position of the annular groove. At this time, the tail of the screw drill sleeve is plastically deformed due to the extrusion of the threaded part of the drill rod at the lower part of the drill rod, forming an opening structure; the opening structure and the end of the drill sleeve are locked together to lock the connected workpiece;

[0022] Step 5: Continue to apply axial force to the upper part of the drill pipe to make it break at the annular groove and finally complete the connection.

[0023] Beneficial effects of the present invention:

[0024] (1) The annular groove inside the screw drill sleeve is combined with the circular protrusion of the drill rod to form a mortise and tenon structure, which can further improve the connection strength. In addition, when the drill rod is pulled upward during the connection process, the cone at the bottom of the drill rod squeezes the tail of the screw drill sleeve to open the open groove. The opened open groove and the end of the drill sleeve will further lock the connected workpiece. In addition, the combination of the annular protrusion and the annular grooves at different positions will form different connection strengths, which provides different connection strength options for different usage scenarios while ensuring the reliability and connection strength of the joint.

[0025] (2) A column of brazing material is added to the circular hole on the screw drill sleeve. After being heated and melted, part of the brazing material flows into the gap between the drill rod and the screw drill sleeve, and part of it flows into the gap between the drill sleeve thread and the hole wall. After cooling, the connection strength can be greatly improved.

[0026] (3) The drill rod and the screw drill sleeve can be made of different materials. The drill rod is made of a material with strong wear resistance, which is mainly used for frictional heat generation and softening of materials. The screw drill sleeve can be made of conventional carbon steel and other materials to achieve high-strength connection of plates. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below in conjunction with the accompanying drawings.

[0028] Figure 1 It is a half-section view of the flow drill screw;

[0029] Figure 2 The overall schematic diagram of the drill pipe;

[0030] Figure 3 It is the overall cross-sectional view of the screw drill sleeve;

[0031] Figure 4 It is a top view of the flow drill screw;

[0032] Figure 5 This is an enlarged cross-sectional view of the micro-texture;

[0033] Figure 6 This is an enlarged cross-sectional view of the standard installation of flow drill screws;

[0034] Figure 7 It is a schematic diagram of the strength connection method of the flow drill screw of the present invention;

[0035] Figure 8 It is a partial enlarged cross-sectional view of the second connection of the flow drill screw strength of the present invention.

[0036] In the figure: 1. drill rod; 2. screw drill sleeve; 3. solder cylinder; 4. top of drill rod; 5. annular groove; 6. annular protrusion; 7. triangular cross rib; 8. drill rod thread; 9. cone; 10. end of drill sleeve; 11. groove at the end of drill sleeve; 12. round hole; 13. drill sleeve thread; 14. micro texture; 15. positioning annular groove; 16. annular groove one; 17. annular groove two; 18. annular groove three; 19. open groove; 20. connected workpiece one; 21. connected workpiece two. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] See also Figures 1 to 6 As shown, the present invention is a novel flow drill screw, which is composed of a drill rod 1, a screw drill sleeve 2 sleeved on the drill rod 1 and a brazing material cylinder 3. The drill rod 1 is composed of a cone 9, a drill rod thread 8, a triangular transverse rib 7, an annular protrusion 6, an annular groove 5 and a drill rod top 4.

[0039] The cone 9 is located at the bottom of the drill rod 1, and is used to reduce the resistance of penetrating the workpiece; the drill rod thread 8 is located at the upper part of the cone 9, and is used to increase the friction heat generated with the workpiece material and reduce the wear of the screw drill sleeve 2. The number of the triangular cross ribs 7 is 2, which are symmetrically distributed and are used to cooperate with the screw drill sleeve 2 to transmit torque, so that the drill rod 1 and the screw drill sleeve 2 rotate synchronously.

[0040] The annular protrusion 6 is located above the triangular transverse rib 7 and is mainly used to control the connection strength of the flow drill screw. During operation, it can cooperate with the annular groove 16, the annular groove 2 17, and the annular groove 3 18 respectively. Suitable annular grooves can be selected according to different materials or different connection strength requirements. The depth of the annular groove 5 is designed according to the connection strength requirements. During the connection process, the drill rod 1 is pulled off from the annular groove, and the top of the drill rod 1 falls off to complete the connection.

[0041] The drill rod thread 8 is of the same size as the screw drill sleeve thread 13; the annular groove 5 is used to pull the drill rod 1 apart and remove the drill rod top 4 after the connection is completed; the cone 9 is used to generate a large amount of heat by friction with the workpiece to soften the workpiece material.

[0042] The screw drill sleeve 2 comprises a drill sleeve thread 13, an annular groove 16, an annular groove 2 17, an annular groove 3 18, a positioning annular groove 15, a micro texture 14, a circular hole 12, a drill sleeve end 10 and a drill sleeve end groove 11. A through hole is provided in the middle of the screw drill sleeve 2, and a drill sleeve end groove 11 is provided on the bottom wall of the drill sleeve end 10 along the circumferential direction; the vertical part of the drill sleeve end 10 is covered by the drill sleeve thread 13, and the thread rotation direction of the drill sleeve thread 13 can be consistent with the thread rotation direction of the drill rod, or can be opposite; the drill sleeve thread 13 section is used to be screwed into the connected workpiece 1 20 and the connected workpiece 2 21, and the length of the thread section is greater than the total thickness of the connected workpieces. The middle part of the through hole has a micro texture 14, which can make the solder have better adhesion after melting; the circular hole 12 is opened at the micro texture 14, the circular hole 12 is a through hole and is symmetrically distributed, and the circular hole 12 is used to place the solder cylinder 3; the lower part of the through hole has four semicircular grooves, the upper three of the semicircular ring grooves are connection strength gear grooves, from top to bottom, they are ring groove three 18, ring groove two 17, and ring groove one 16, and the connection strength decreases successively. The fourth semicircular groove is a positioning ring groove 15, which is used for positioning the drill rod 1 and the screw drill sleeve 2 during standard installation; the bottom of the screw drill sleeve 2 has an open groove 19 that passes through the axis in the vertical direction, which is used to cooperate with the triangular cross rib 7 on the drill rod 1 to transmit torque and make the drill rod 1 and the screw drill sleeve 2 rotate synchronously; the width of the open groove 19 is consistent with the width of the triangular cross rib 7.

[0043] The standard installation state of the flow drill screw is that the drill rod 1 passes through the through hole of the screw drill sleeve 2, and the annular protrusion 6 of the drill rod 1 and the positioning annular groove 15 of the screw drill sleeve 2 form a mortise and tenon structure fit; the through hole of the drill rod 1 and the screw drill sleeve 2 is a clearance fit.

[0044] During the connection process, when the drill rod 1 is pulled upward, the annular protrusion 6 of the drill rod 1 can be separated from the standard installation position and enter the annular groove 1 16 position to form a first-level connection strength, and enter the annular groove 2 17 and the annular groove 3 18 positions to form corresponding second-level connection strength and third-level connection strength. According to the connection strength requirements, the flow drill screw can be prepared into specifications of different connection strengths to match the annular grooves 5 of different sizes. For example, in the flow drill screw of the second-level connection strength specification, the annular protrusion 6 can enter the annular groove 2 17 during the pulling process, and when the pull continues upward, it will break at the annular groove 5.

[0045] refer to Figure 7 and Figure 8 As shown, a novel rotary friction connection method of a flow drill screw comprises the following steps:

[0046] Step 1: Select a flow drill screw with a second-level connection strength, and match the drill rod 1 and the screw drill sleeve 2 to a standard installation state. Use the installation tool to place the flow drill screw on the surface of the workpiece 20 to be connected.

[0047] Step 2, start the installation tool, the installation tool drives the flow drill screw to rotate and feed downward along the axis at the same time, the cone 9 of the drill rod 1 rubs against the surface of the connected workpiece 20, the frictional heat softens the connected workpiece 20, and the cone 9 continuously drills into the connected workpiece.

[0048] Step 3: As the flow drill screw continues to rotate and feed, the screw drill sleeve 2 passes through the connected workpiece 1 20 and the connected workpiece 2 21 until the lower end surface of the drill sleeve end 10 of the screw drill sleeve 2 contacts the upper end surface of the connected workpiece 1 20, and squeezes the overflowing material into the groove 11 at the end of the drill sleeve. In this process, since the outer wall of the screw drill sleeve is a tapered thread, it can continuously squeeze the workpiece material to ensure that the thread section is in continuous contact with the perforated hole wall. The brazing material cylinder 3 melts in this process, a part of it flows into the threaded area to fill the gap between the thread and the hole wall, and the other part flows into the gap between the drill rod 1 and the screw drill sleeve 2, and the drill rod 1 and the screw drill sleeve 2 are tightly combined after cooling and solidification.

[0049] Step 4, start the upward lifting device in the installation tool, pull the drill rod 1 upward, so that the drill rod 1 and the screw drill sleeve 2 produce relative displacement, the annular protrusion 6 of the drill rod disengages from the positioning annular groove 15 and enters the annular groove 1 16, continue to pull the drill rod 1, the annular protrusion 6 disengages from the annular groove 16 and enters the annular groove 2 17, at this time, the opening groove 19 is continuously squeezed by the drill rod thread 8, and the opening angle increases, and the drill rod 1 is continued to be pulled to break at the annular groove 5, and finally the second-level connection strength is formed, such as Figure 8 shown.

[0050] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A new type of flow drill screw, comprising a drill rod (1), a screw drill sleeve (2) sleeved on the drill rod (1) and a brazing material cylinder (3), characterized in that: The screw drill sleeve (2) is a hollow structure and forms a clearance fit with the drill rod (1). The screw drill sleeve (2) is provided with a plurality of circular holes (12) for mounting the brazing material cylinder (3). The annular protrusion (6) on the drill rod (1) cooperates with annular groove 1 (16), annular groove 2 (17) and annular groove 3 (18) on the screw drill sleeve (2) to form a mortise and tenon structure.

2. A new type of flow drill screw according to claim 1, characterized in that: The drill rod (1) comprises a drill rod top (4), an annular groove (5), an annular protrusion (6), a triangular transverse rib (7), a drill rod thread (8) and a cone (9); the cone (9) is located at the bottom of the drill rod (1); the drill rod thread (8) is located at the upper part of the cone (9); the triangular transverse rib (7) is symmetrically distributed and is used to cooperate with a screw drill sleeve (2) to transmit torque, so that the drill rod (1) and the screw drill sleeve (2) rotate synchronously.

3. A new type of flow drill screw according to claim 1, characterized in that: The top (4) of the drill rod is provided with an annular groove (5). During the connection process, the drill rod (1) is pulled off from the annular groove (5), and the top of the drill rod (1) falls off, thus completing the connection.

4. A new type of flow drill screw according to claim 1, characterized in that: The screw drill sleeve (2) comprises a drill sleeve end (10), on which a drill sleeve end groove (11) is arranged, and the drill sleeve end groove (11) is used to store extruded workpiece material, and the drill sleeve end (10) is provided with a drill sleeve thread (13) on the outside, the drill sleeve thread (13) has a size consistent with that of a drill rod thread (8), and the length of the drill sleeve thread (13) section is greater than the thickness of the connected workpiece.

5. A new type of flow drill screw according to claim 4, characterized in that: The inner surface of the screw drill sleeve (2) is provided with a micro texture (14), and an annular groove three (18), an annular groove two (17), an annular groove one (16) and a positioning annular groove (15) are sequentially provided below the micro texture (14).

6. A new type of flow drill screw according to claim 1, characterized in that: The lower part of the screw drill sleeve (2) is provided with an open groove (19), and the open grooves (19) are symmetrically distributed and form a small clearance fit with the triangular transverse ribs (7) on the drill rod (1).

7. A new type of flow drill screw according to claim 1, characterized in that: The solder cylinder (3) is installed at the circular hole (12) of the screw drill sleeve (2). During the connection process, the friction heat generated by the flow drill screw causes the solder cylinder to melt, part of which flows into the gap between the drill rod (1) and the screw drill sleeve (2), and part of which flows into the gap between the drill sleeve thread (2) and the connection material, thereby strengthening the connection.

8. A new type of flow drill screw according to claim 1, characterized in that: The drill rod (1) and the screw drill sleeve (2) are respectively made of different materials; the drill rod (1) is made of a highly wear-resistant material, and the screw drill sleeve (2) is made of carbon steel.

9. A novel method for rotating friction connection of flow drill screws, characterized in that: The following steps are involved: Step 1: Assemble the brazing material cylinder (3), the drill rod (1) and the screw drill sleeve (2), install the annular protrusion (6) of the drill rod to fit the annular groove at the bottom of the screw drill sleeve (2), and then use the installation tool to place the flow drill screw on the surface of the workpiece to be processed; Step 2: Start the installation tool, which drives the flow drill screw to rotate at high speed and feed along the axial direction. The cone (9) of the drill rod (1) rubs against the workpiece material to generate a large amount of heat, which softens the workpiece material. The cone (9) continuously drills into the connected workpiece. Step 3: As the cone (9) is continuously drilled, the screw drill sleeve (2) is also drilled into the connected workpiece. As the drilling distance increases, the flow drill screw penetrates the connected workpiece until the lower surface of the drill sleeve end (10) contacts the upper surface of the connected workpiece, and the overflowed plastic material is squeezed into the groove (11) at the end of the drill sleeve; Step 4: Pull the drill rod (1) upwards by means of the installation tool, so that the drill rod (1) and the screw drill sleeve (2) are relatively displaced, and the annular protrusion (6) of the drill rod (1) is disengaged from the positioning annular groove (15) and enters the position of the annular groove 1 (16). At this time, the rear end of the screw drill sleeve is plastically deformed due to the extrusion of the drill rod thread (8) at the lower part of the drill rod, forming an opening structure; the opening structure and the drill sleeve end (10) together lock the connected workpiece; Step 5: Continue to apply axial force to the upper part of the drill rod (1) to cause it to break at the annular groove (5), and finally complete the connection.

Images