A new flow-drilling screw and a rotary friction connection method thereof

Abstract

The application discloses a novel flow-drilling screw and a rotating friction connecting method thereof, and relates to the technical field of screw connection, which comprises a drill rod, a screw drill sleeve arranged on the drill rod and a filler cylinder, the screw drill sleeve is of a hollow structure and is in clearance fit with the drill rod, a plurality of round holes are formed in the screw drill sleeve and are used for mounting the filler cylinder, an annular protrusion on the drill rod is matched with annular grooves one, two and three on the screw drill sleeve, and a mortise and tenon structure is formed. In the connecting process, the drill rod is pulled upward, a lower conical body of the drill rod extrudes a tail part of the screw drill sleeve to make an opening groove expand, the expanded opening groove forms a mechanical interlocking structure with an end part of the drill sleeve, workpieces can be locked, and the connection of high-strength plates can be realized. In addition, the mortise and tenon structure formed by the annular grooves in the screw drill sleeve and the annular protrusion of the drill rod can further improve the connecting strength and the connecting reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of screw connection, in particular to a novel flow-drilling screw and a rotating friction connection method thereof. BACKGROUND

[0002] Flow-drilling screw connection technology, also known as hot melting self-tapping connection technology, is a technology that uses a high-speed rotating screw to heat a metal plate under a certain pressure, causing the metal plate to soften locally, and finally the screw penetrates the metal plate and forms a thread fastening connection. This technology can achieve single-sided connection with less deformation. Flow-drilling screws can connect the same and different materials, and have been applied to steel-aluminum hybrid body framework structures, such as the connection of aluminum workpiece materials, composite materials, and high-strength steel plates, to achieve lightweight and high-strength of the vehicle body structure.

[0003] Chinese patent CN115143177B discloses a flow-drilling screw and a fastening device thereof. The flow-drilling screw has an inner through hole along the axial direction, which penetrates the screw cap and the screw rod. The inner through hole allows an external high-power heat source to input and reach the surface of the workpiece. The simplified tail cone structure of the flow-drilling screw shortens the length of the flow-drilling screw. However, the flow-drilling screw does not have a locking structure, and the connected workpiece is prone to loosening under the action of long-term cyclic load.

[0004] Chinese patent CN108799291A discloses a hot melting drilling riveting rivet and a drilling riveting connection method. The hot melting drilling riveting rivet includes a core rod and a rivet cap. The head of the core rod is used for drilling the connected workpiece, and the rivet cap is used for riveting the connected workpiece. The method mainly uses the core rod to complete drilling and uses the compression or expansion of the rivet cap to form a compressed workpiece. There is a certain gap between the rivet cap and the workpiece material, which cannot achieve a tight connection.

[0005] Chinese patent CN117605746A discloses a hot melting drilling riveting rivet for connecting thermoplastic composite materials and metals. The rivet is composed of a core rod and a rivet sleeve. During the riveting process, the lower riveting segment can be compressed into a drum shape to form a lower rivet cap, which, together with the rivet cap, locks the riveted workpiece. However, this structure also has some deficiencies. First, the hollow tail of the shaft rod is cylindrical and has a blind hole, which is not conducive to drilling into the connected workpiece material. When the blind hole is filled with the connected material, it will be more difficult for the shaft rod to continue drilling into the lower layer of material, especially when the lower layer of workpiece material is a high-strength plate or other material. Second, the through hole of the shaft rod and the rivet sleeve are in interference fit. Before the rivet sleeve forms a rivet cap under the action of external tension, the shaft rod is prone to break at the breakpoint ring groove.

[0006] In engineering applications, the connection of workpieces made of different materials, especially some high-strength plates, requires higher requirements for flow drilling screws, and the connection strength is also higher, and the existing flow drilling screw structure cannot meet the demand. SUMMARY

[0007] The purpose of the present application is to solve the problem that the existing flow drilling screw cannot realize mechanical interlocking and high-strength connection when connecting high-strength plates.

[0008] The purpose of the present application can be achieved by the following technical solutions:

[0009] A novel flow drilling screw comprises a drill rod, a screw drill sleeve arranged on the drill rod, and a filler cylinder, wherein the screw drill sleeve is a hollow structure and is in clearance fit with the drill rod, a plurality of round holes are formed in the screw drill sleeve for mounting the filler cylinder.

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

[0011] As a further scheme of the present application, the drill rod comprises 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, the triangular cross ribs are symmetrically distributed and are used for cooperating with the screw drill sleeve to transmit torque and make the drill rod and the screw drill sleeve rotate synchronously.

[0012] As a further scheme of the present application, an annular groove is formed in the top of the drill rod, the drill rod is pulled off from the annular groove during the connection process, the top of the drill rod is separated, and the connection is completed.

[0013] As a further scheme of the present application, the screw drill sleeve comprises a drill sleeve end, the drill sleeve end is provided with a drill sleeve end groove, the drill sleeve end groove is used for storing the workpiece material extruded out, the outer part of the drill sleeve end is provided with a drill sleeve thread, the size of the drill sleeve thread is consistent with the size of the drill rod thread, and the length of the drill sleeve thread section is greater than the thickness of the workpiece to be connected.

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

[0015] As a further scheme of the present application, an open slot is formed in the lower part of the screw drill sleeve, and the open slots are symmetrically distributed and are in small clearance fit with the triangular cross ribs on the drill rod.

[0016] As a further scheme of the present application, the drill rod and the screw drill sleeve are respectively made of dissimilar materials; the drill rod is made of high wear resistance material, and the screw drill sleeve is made of carbon steel material.

[0017] As a further scheme of the present application: a new type of flow drill screw rotation friction connection method, comprising the following steps:

[0018] Step one, assemble the drill rod and the screw drill sleeve with the filler cylinder, install the annular protrusion of the drill rod into the annular groove at the lowermost part 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 two, 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 generates a large amount of heat by friction with the workpiece material to soften the workpiece material, and the cone continuously drills into the connected workpiece;

[0020] Step three, as the cone continuously drills in, the screw drill sleeve also drills into the connected workpiece, and as the drilling distance increases, the flow drill screw penetrates the connected workpiece until the lower surface of the end of the drill sleeve contacts the upper surface of the connected workpiece, and the overflow plastic material is extruded into the recess at the end of the drill sleeve;

[0021] Step four, pull the drill rod upward through the installation tool to make the drill rod and the screw drill sleeve produce relative displacement, the annular protrusion of the drill rod is out of the positioning annular groove and enters the annular groove position, at this time, the tail of the screw drill sleeve is plastically deformed due to the extrusion of the lower threaded part of the drill rod, forming an open structure; the open structure together with the end of the drill sleeve locks the connected workpiece;

[0022] Step five, continue to apply axial force to the upper part of the drill rod to make it break at the annular groove, and finally complete the connection.

[0023] The beneficial effects of the present application are:

[0024] (1) The annular groove in the screw drill sleeve and the circular protrusion of the drill rod combine to form a mortise and tenon structure, which can further improve the connection strength. Moreover, during the connection process, the drill rod is pulled upward, the lower cone of the drill rod extrudes the tail of the screw drill sleeve to open the open slot, and the open slot together with the end of the drill sleeve further locks the connected workpiece. In addition, the annular protrusion combined with the annular groove at different positions will form different connection strengths, which provides different connection strengths for different use scenarios while ensuring the reliability and connection strength of the joint.

[0025] (2) The filler cylinder is added in the circular hole of the screw drill sleeve, and after being heated and melted, part of the filler flows into the gap between the drill rod and the screw drill sleeve, and part of the filler flows into the gap between the drill sleeve thread and the hole wall, which can greatly improve the connection strength after cooling.

[0026] (3) The drill rod and the screw drill sleeve can be made of different materials respectively, the drill rod is made of a material with strong wear resistance, mainly used for friction heating and softening the material, and the screw drill sleeve can be made of a conventional carbon steel, etc. to realize high-strength connection of the plate. Attached Figure Description

[0027] The invention will now be further described with reference to the accompanying drawings.

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

[0029] Figure 2 This is a schematic diagram of the drill pipe as a whole;

[0030] Figure 3 This is a cross-sectional view of the screw drill bushing as a whole;

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

[0032] Figure 5 This is a magnified cross-sectional view of the microtexture area;

[0033] Figure 6 Enlarged sectional view of the standard installation of flow drill screws;

[0034] Figure 7 This is a schematic diagram of the strength-based two-connection method for the flow drill screw of the present invention;

[0035] Figure 8 This is a partially enlarged cross-sectional view of the connection point of the flow drill screw strength two of the present invention.

[0036] In the diagram: 1. Drill rod; 2. Screw drill sleeve; 3. Brazing filler cylinder; 4. Top of drill rod; 5. Annular groove; 6. Annular protrusion; 7. Triangular transverse rib; 8. Drill rod thread; 9. Cone; 10. Drill sleeve end; 11. Drill sleeve end groove; 12. Circular hole; 13. Drill sleeve thread; 14. Microtexture; 15. Positioning annular groove; 16. Annular groove one; 17. Annular groove two; 18. Annular groove three; 19. Opening groove; 20. Connected workpiece one; 21. Connected workpiece two. Detailed Implementation

[0037] 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 only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Please see Figures 1 to 6 As shown, this invention is a novel flow drill screw, which consists of a drill rod 1, a screw drill sleeve 2 fitted onto the drill rod 1, and a brazing filler cylinder 3. The drill rod 1 consists 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 conical body 9 is located at the bottom of the drill rod 1, used to reduce the resistance of penetrating the workpiece; the drill rod thread 8 is located at the upper part of the conical body 9, used to increase the friction heat with the workpiece material, reduce the wear of the screw drill sleeve 2, the number of the triangular cross rib 7 is 2, symmetrically distributed, 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 cross rib 7, mainly used for the control of the flow drilling screw connection strength, and in the working process, can form cooperation with the annular groove one 16, the annular groove two 17 and the annular groove three 18 respectively, and the appropriate annular groove can be selected according to the different materials or different connection strength requirements. The depth of the annular groove 5 is designed according to the connection strength requirement, in the connection process, the drill rod 1 is pulled off from the annular groove, the top of the drill rod 1 falls off, and the connection is completed.

[0041] The drill rod thread 8 is consistent with the screw drill sleeve thread 13 in size; the annular groove 5 is used to pull off the drill rod 1 after the connection is completed, and remove the top of the drill rod 4; the conical body 9 is used to produce a large amount of heat by friction with the workpiece to soften the workpiece material.

[0042] The screw drill sleeve 2 includes the drill sleeve thread 13, the annular groove one 16, the annular groove two 17, the annular groove three 18, the positioning annular groove 15, the micro texture 14, the round hole 12, the drill sleeve end 10 and the drill sleeve end groove 11. The screw drill sleeve 2 is provided with a through hole in the middle, and the drill sleeve end groove 11 is opened on the bottom wall of the drill sleeve end 10 in the circumferential direction; the vertical part of the drill sleeve end 10 is covered by the drill sleeve thread 13, and the thread direction of the drill sleeve thread 13 can be consistent with or opposite to that of the drill rod thread; the drill sleeve thread 13 is used to be screwed into the connected workpiece one 20 and the connected workpiece two 21, and the length of the threaded section is greater than the total thickness of the connected workpieces. The middle part of the through hole is provided with the micro texture 14, which can make the brazing material have better adhesion after melting; the round hole 12 is arranged at the micro texture 14, the round hole 12 is a through hole and is symmetrically distributed, and the round hole 12 is used to place the brazing cylinder 3; the lower half of the through hole has four semicircular grooves, the upper three semicircular grooves are connection strength grade grooves, and from top to bottom, they are the annular groove three 18, the annular groove two 17 and the annular groove one 16, and the connection strength is weakened in turn. The fourth semicircular groove is the positioning annular groove 15, which is used for positioning when the drill rod 1 and the screw drill sleeve 2 are installed in standard; the lowermost part of the screw drill sleeve 2 has an opening groove 19 passing through the axis in the vertical direction, which is used to cooperate with the triangular cross rib 7 on the drill rod 1, transmit torque and make the drill rod 1 and the screw drill sleeve 2 rotate synchronously; the width of the opening 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 is matched with the positioning annular groove 15 of the screw drill sleeve 2 to form a mortise and tenon structure.

[0044] During the connecting process, the annular protrusion 6 of the drill rod 1 can be separated from the standard installation position and enter the annular groove one 16 position to form a first gear connecting strength, and enter the annular groove two 17 and the annular groove three 18 positions to form corresponding second gear connecting strength and third gear connecting strength. According to the connecting strength requirement, the flow drill screw can be prepared into different specifications of connecting strength to match different sizes of annular grooves 5. For example, the flow drill screw of the second gear connecting strength specification can make the annular protrusion 6 enter the annular groove two 17 during the pulling process, and when continuing to pull upward, the annular groove 5 will be broken.

[0045] Reference Figure 7 and Figure 8 As shown in the figure, a new rotary friction connecting method of the flow drill screw includes the following steps:

[0046] Step one, select the flow drill screw of the second gear connecting strength, and match the drill rod 1 and the screw drill sleeve 2 to the standard installation state. Use the installation tool to place the flow drill screw on the surface of the connected workpiece one 20.

[0047] Step two, start the installation tool, the installation tool drives the flow drill screw to rotate and simultaneously feeds downward along the axis, the conical body 9 of the drill rod 1 generates friction on the surface of the connected workpiece one 20, the friction generates heat to soften the connected workpiece one 20, and the conical body 9 continuously drills into the connected workpiece.

[0048] Step three, as the flow drill screw continues to rotate and feed, the screw drill sleeve 2 passes through the connected workpiece one 20 and the connected workpiece two 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 one 20, and extrudes the overflow material to the drill sleeve end groove 11. In this process, since the outer wall surface of the screw drill sleeve is a tapered thread, it can continuously extrude the workpiece material to ensure that the thread section continuously contacts the perforated hole wall, the filler metal cylinder 3 melts in this process, part of it flows into the thread 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 after cooling and solidification, the drill rod 1 and the screw drill sleeve 2 are tightly combined.

[0049] Step four, start the installation tool in the upward lifting device, pull up the drill pipe 1, make the drill pipe 1 and the screw drill sleeve 2 relative displacement, the annular protrusion 6 of the drill pipe is out of the positioning annular groove 15, enters the annular groove one 16, continue to pull the drill pipe 1, the annular protrusion 6 is out of the annular groove one 16, enters the annular groove two 17, at this time the open slot 19 is subjected to the continued extrusion of the part of the drill pipe thread 8 and the angle of opening increases, continue to pull the drill pipe 1 and break at the ring groove 5, finally form the two gear connection strength, as shown in Figure 8

[0050] The above has carried out the detailed description to one embodiment of the application, but the content described is only the preferred embodiment of the application, cannot be considered for limiting the implementation scope of the application. All equivalent changes and improvements made according to the scope of the application are still attributed to the patent coverage range of the application.​

Claims

1. A novel flow-drill screw comprising a drill rod (1), a screw drill sleeve (2) sleeved on the drill rod (1), and a filler cylinder (3), characterized in that, The screw drill sleeve (2) is a hollow structure, and is in clearance fit with the drill rod (1). A plurality of round holes (12) are formed in the screw drill sleeve (2) and used for mounting the filler material cylinder (3). The annular protrusion (6) on the drill rod (1) is in fit with the annular groove one (16), the annular groove two (17) and the annular groove three (18) on the screw drill sleeve (2), so as to form a mortise and tenon structure. The drill rod (1) comprises a drill rod top (4), an annular groove (5), an annular protrusion (6), a triangular horizontal 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), and the triangular horizontal ribs (7) are symmetrically distributed and used for being in fit with the screw drill sleeve (2) so as to transmit torque and make the drill rod (1) and the screw drill sleeve (2) rotate synchronously. The screw drill sleeve (2) comprises a drill sleeve end (10), the drill sleeve end (10) is provided with a drill sleeve end groove (11) used for storing the extruded workpiece material, and the outer part of the drill sleeve end (10) is provided with a drill sleeve thread (13) having the same size as the drill rod thread (8) and having a length greater than the thickness of the connected workpiece.

2. A novel flow-drill screw as claimed in claim 1, wherein, The annular groove (5) is formed in the drill rod top (4), the drill rod (1) is pulled off from the annular groove (5) during the connecting process, the top of the drill rod (1) is separated, and the connection is completed.

3. A novel flow-drill screw as claimed in claim 1, wherein, The inner surface of the screw drill sleeve (2) is provided with micro-texture (14), and the micro-texture (14) is sequentially provided with the annular groove three (18), the annular groove two (17), the annular groove one (16) and the positioning annular groove (15).

4. A novel flow-drill screw as claimed in claim 1, wherein, The lower part of the screw drill sleeve (2) is provided with an open slot (19) which is symmetrically distributed and is in small clearance fit with the triangular horizontal rib (7) on the drill rod (1).

5. A novel flow-drill screw as claimed in claim 1, wherein: The filler material cylinder (3) is mounted at the round hole (12) of the screw drill sleeve (2), the filler material cylinder is melted due to the frictional heat generated during the connecting process of the flow drill screw, part of the filler material cylinder flows into the gap between the drill rod (1) and the screw drill sleeve (2), and part of the filler material cylinder flows into the gap between the drill sleeve thread (13) and the connecting material, so that the connection is strengthened.

6. A novel flow-drill screw as claimed in claim 1, wherein, The drill rod (1) and the screw drill sleeve (2) are respectively made of different materials, the drill rod (1) is made of high wear-resistant material, and the screw drill sleeve (2) is made of carbon steel material.

7. A method of rotary friction connection of a new flow-drill screw, characterized in that, The new flow drill screw of claim 1 comprises the following steps: Step one, the filler material cylinder (3), the drill rod (1) and the screw drill sleeve (2) are assembled, the annular protrusion (6) of the drill rod is installed and fitted to the lowermost annular groove of the screw drill sleeve (2), and then the flow drill screw is placed on the surface of the workpiece to be processed by using an installation tool; Step two, the installation tool is started, the installation tool drives the flow drill screw to rotate at high speed and feeds along the axial direction, the cone (9) of the drill rod (1) generates a large amount of heat by friction with the workpiece material, the workpiece material is softened by the heat, and the cone (9) continuously drills into the connected workpiece. Step three, with the continuous drilling of the cone (9), the screw drill sleeve (2) also follows the drilling into the connected workpiece, with the increase of the drilling distance, the flow drilling 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 overflow plastic material is extruded into the drill sleeve end groove (11); Step four, pull the drill rod (1) upward through the installation tool, make the drill rod (1) and the screw drill sleeve (2) produce relative displacement, the annular protrusion (6) of the drill rod (1) is out of the positioning annular groove (15) and enters the annular groove (16) position, at this time, the screw drill sleeve tail is plastically deformed due to the extrusion of the lower part of the drill rod thread (8), forming an open structure; The open structure together with the drill sleeve end (10) locks the connected workpiece; Step five, continue to apply axial force to the upper part of the drill rod (1), so that it breaks at the annular groove (5), and finally completes the connection.

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