Rivet overturn preventive automatic feeding device for rivet joint device

Abstract

To provide a rivet overturn preventive automatic feeding device for a rivet joint device.SOLUTION: A rivet overturn preventive automatic feeding device includes a feeding body, a punch rod, and a rivet guide mechanism. The rivet guide mechanism includes a guide joint, a guide cylinder, and a rivet feeding nozzle installed in the guide cylinder. A few annular passages for mounting a flexible member are provided in an exterior wall circumferential direction of the rivet feeding nozzle, and the rivet feeding nozzle forms a guide passage for connecting several circular arc-shaped pieces and pushing out a rivet. The rivet is punched downward by action of the punch rod, and is pushed into the terminal of the guide passage and is fixed and joined to the plate of a rivet joint target. The rivet feeding nozzle formed by connecting the several circular arc-shaped pieces is installed, which imparts equal fastening stress in a circumferential direction to the rivet, can adapt to compression deformation generated when the rivet is inclined or overturned, and effectively lowers a rivet overturn ratio.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rivet fastening device, and more particularly to an automatic rivet feeder that prevents rivet tipping over for a fastening device that uses a self-piercing rivet (SPR). [Background technology]

[0002] Riveting using SPR (Self-piercing Rivet) is an important joining technology that reduces the weight of automobiles, saves energy and reduces emissions, and increases the driving range of new energy vehicles.

[0003] Riveting using self-piercing rivets is a riveting process in which an SPR rivet penetrates a plate under the action of external force and then flows and expands within the underlying plate, creating interlocking plastic deformation. The resulting riveted joint has high tensile and shear strength. Self-piercing rivet joining technology solves the problem of aluminum spot welding technology being unable to meet joining performance requirements, overcoming issues such as insufficient fatigue strength and incompatibility between the rivet coating and the aluminum material. The rivet roll rate is an important control index for ensuring the quality of riveted joints.

[0004] Conventional self-piercing rivet fastening devices have a rotatable steel ball array fitted at 120° intervals on a rivet feed rail, which supports and guides the rivet, and an air blowing device installed at the end of the rivet feed rail to generate a counter force on the rivet, so that the rivet is held stably and does not tip over due to the action of the supporting force of the steel balls, the air pressure, and the impact force of the guide rod.

[0005] However, the rivet feed guide rails of such devices lack elasticity and cannot accommodate errors in material dimensions or process changes, making it difficult to accurately control the size and direction of the airflow from the air blowing device. This is particularly incompatible with rivets with a small length-to-diameter ratio, resulting in a high probability of rivet tipping or tilting (1 / 200). This seriously affects production efficiency and leads to unstable quality of rivet joints.

[0006] Therefore, it is necessary to design a rivet feeder that prevents tipping and tilting specifically for the SPR riveting machine to solve the above problems. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned problems in the prior art by providing an automatic rivet feeder for a riveting machine that prevents rivet rollover. [Means for solving the problem]

[0008] To achieve the above objectives, the present invention provides the following technical solutions:

[0009] An automatic rivet feeder preventing lateral tipping for a self-piercing rivet fastening device includes a feeder body, a punch rod, and a rivet guide mechanism, the feeder body has punch through holes formed from top to bottom, the punch rod extends through the punch through holes, the upper end of the feeder body is connected to a power head of the riveting device via the top end of the punch rod, a lateral passage for transporting rivets is formed in the lower end of the feeder body, a belt for transporting rivets extends through the lateral passage, and the end of the punch through hole extending vertically through the lateral passage is connected to the rivet guide mechanism.

[0010] The rivet guide mechanism includes a guide joint, a guide tube, and a rivet feed nozzle installed in the guide tube. A number of annular passages are provided around the outer wall of the rivet feed nozzle for attaching a flexible member. The rivet feed nozzle connects a number of arc-shaped pieces to form a guide passage for pushing out the rivet. The top end of the rivet feed nozzle protrudes from the top end of the guide tube and abuts against the end of the punch through-hole via the guide joint.

[0011] The end of the punch rod punches downward toward the rivet on the belt under the action of power applied by the power head, applying a downward punch force E, which pushes the rivet into the end of the guide passage and securely joins it with the plate to be riveted. At the same time, the rivet feed nozzle, formed by connecting several arc-shaped pieces, applies a circumferential clamping stress δ to the rivet driven by the punch rod, which grips the rivet. This circumferential clamping stress δ corresponds to the tightening degree of the flexible member. When the length of the rivet feed nozzle is L1, the number of arc-shaped pieces of the rivet feed nozzle is N, the moving tact of each rivet on the belt is t, and the rivet head diameter is D and length is L2, the rivet roll rate y is determined according to the following formula:

[0012]

number

[0013] (In the formula, y is the rivet roll rate (‰), N is the number of arc-shaped pieces of the rivet feed nozzle (unitless), E is the punch force of the punch rod (kN), D is the rivet head diameter (mm), L1 is the rivet feed nozzle length (mm), L2 is the rivet length (mm), δ is the circumferential clamping stress (MPa), t is the movement tact (s) of each rivet on the belt, and k and α are both constants.) As a preferred technical solution of the present invention, at least two annular passages for attaching flexible members are provided in the circumferential direction of the outer wall of the rivet feeding nozzle.

[0014] As a preferred technical solution of the present invention, two or three annular passages for attaching flexible members are provided around the outer wall of the rivet feed nozzle, the flexible members are O-rings made of nitrile rubber, and at least two flexible members are provided.

[0015] As a preferred technical solution of the present invention, the rivet feeding nozzle is made up of three arc-shaped pieces connected together to form a guide passage for pushing out the rivet.

[0016] As a preferred technical solution of the present invention, the guide joint has an inner wall having a first bell mouth that is larger at the top and smaller at the bottom, and the inner wall of the upper end of the rivet feed nozzle at the point where it abuts against the first bell mouth forms a second bell mouth, and the inner diameter of the bottom end of the first bell mouth is smaller than the inner diameter of the top end of the second bell mouth.

[0017] In the preferred technical solution of the present invention, the circumferential clamping force F is composed of lateral pressures exerted by several arc-shaped pieces of the rivet feed nozzle, the magnitude of the lateral pressures is the same, the direction is all horizontally directed towards the center of the rivet tip, and the number of the lateral pressures is the same as the number of the arc-shaped pieces. [Effects of the Invention]

[0018] The advantageous effects of the present invention are as follows:

[0019] (1) The rivet feed nozzle in the rivet guide mechanism is formed by connecting several equally divided arc-shaped pieces, and the arc-shaped pieces apply an even circumferential clamping stress to the rivet propelled by the punch rod. As a result, the rivet generates an even frictional force between the rivet and the contact surface of the rivet feed nozzle due to the action of the circumferential clamping stress, keeping the rivet's posture balanced and preventing the rivet from tipping, tilting or deforming due to uneven force, thereby reducing breakdowns or quality issues caused by the force applied.

[0020] (2) In the rivet feed nozzle, the gap between the arc-shaped pieces can accommodate the compressive deformation that occurs when the rivet is tilted or overturned, providing the rivet feed nozzle with a certain elastic deformation force. When the rivet is tilted or overturned, the arc-shaped pieces are compressed by the rivet and expand outward relative to the center of the rivet, widening the gap between the arc-shaped pieces. The deformation of the gap between the arc-shaped pieces further absorbs the energy generated when the rivet is tilted or overturned, reducing the amount of tilt or overturn of the rivet and thereby stabilizing the position and posture of the rivet. At this time, the arc-shaped pieces act against the rivet, correcting it from an inclined state to a horizontal state, effectively reducing rivet overturn and improving the accuracy and success rate of riveting. Compared to the rigid rivet feed nozzle of conventional riveting equipment, the automatic rivet overturn prevention feeder for self-piercing riveting equipment of the present invention reduces the rivet overturn rate by 1 / 200 to 1 / 1000.

[0021] (3) The gaps between the arc-shaped pieces provide the arc-shaped pieces with a certain cushioning force, so that the arc-shaped pieces do not suddenly collide when compressed, but adapt to the force by gradually deforming. This effectively reduces the impact and wear to the inside of the device caused by rivets that are too large or inclined, reduces the risk of device failure, and extends the service life of the device.

[0022] (4) By utilizing the good elasticity of the flexible member, a certain gripping force is applied to the rivet feed nozzle, which consists of several arc-shaped pieces, making the arc-shaped pieces tightly adhere to each other, thereby improving the gripping stability of the rivet feed nozzle on the rivet.

[0023] (5) A quantitative relationship is established between the rivet roll rate and parameters such as the punch force of the punch rod, the length and number of pieces of the rivet feed nozzle, the movement tact of each rivet on the belt, the rivet dimensions, and the circumferential clamping stress applied by the rivet feed nozzle, and a control formula for the rivet roll rate is derived through numerical curve fitting. Based on the control formula, a clear and effective guide can be provided for the rivet roll rate in actual production, and by monitoring and adjusting related parameters, the rivet roll rate can be further adjusted to meet production requirements. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is an exploded view of an automatic rivet feeder with anti-overturn mechanism for a self-piercing rivet fastening device according to the present invention. FIG. [Figure 2] 1 is a cross-sectional view of an automatic rivet overturn prevention device for a self-piercing riveting apparatus according to the present invention. FIG. [Figure 3] FIG. 2 is a cross-sectional view of a rivet guide mechanism according to the present invention. [Figure 4] 1 is a schematic diagram of a rivet feed nozzle according to the present invention; [Figure 5] FIG. 5 is an enlarged view of a portion A in FIG. [Figure 6] FIG. 10 is a diagram showing the functional relationship between the movement tact and the rivet rollover rate in a specific embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for the purpose of explanation and illustration only and are not intended to limit the present invention.

[0026] It should be noted that, in order to facilitate a thorough understanding of the present invention, many specific details are described in the following description, but the present invention may have other embodiments and modifications thereof, and therefore the scope of protection of the present invention is not limited to the specific examples disclosed below.

[0027] As shown in FIGS. 1 and 2, the automatic rivet feeder for preventing rivet overturning provided by the present invention for a self-piercing rivet fastening device includes a feeder body 1, a punch rod 3, and a rivet guide mechanism 2.

[0028] Punch holes 10 are provided from top to bottom in feeder body 1, and punch rods 3 are inserted through punch holes 10. The upper end of feeder body 1 is connected to the power head (not shown) of the riveting device via the top ends of punch rods 3, a horizontal passage 11 for transporting rivets is provided in the lower end of feeder body 1, and a belt 4 for transporting rivets is inserted through horizontal passage 11. The end of punch hole 10, which passes vertically through horizontal passage 11, is connected to rivet guide mechanism 2.

[0029] As shown in Figure 3, the rivet guide mechanism 2 includes a guide joint 21, a guide tube 24, and a rivet feed nozzle 22 installed in the guide tube. A number of annular passages 222 are provided around the outer wall of the rivet feed nozzle 22 for attaching a flexible member 23. The rivet feed nozzle 22 connects a number of arc-shaped pieces 220 to form a guide passage 223 for pushing out a rivet, and the top end of the rivet feed nozzle 22 protrudes from the top end of the guide tube 24 and abuts against the end of the punch through hole 10 via the guide joint 21.

[0030] 1 and 2, the end of punch rod 3 is acted upon by the power provided by the power head to punch downward at the rivet on belt 4, applying a downward punch force E, which pushes the rivet into the end of guide passage 223 and securely joins it to the plate (not shown) to be riveted. At the same time, rivet feed nozzle 22, formed by connecting several arc-shaped pieces 220, applies a circumferential clamping stress δ to the rivet propelled by punch rod 3 to hold the rivet in place, and the circumferential clamping stress δ corresponds to the degree of tightening of flexible member 23.

[0031] When the length of the rivet feed nozzle 22 is L1, the number of arc-shaped pieces of the rivet feed nozzle is N, the moving tact of each rivet on the belt is t, the head diameter of the rivet is D, and the length is L2, the following formula is satisfied in determining the rivet rollover rate y.

[0032]

number

[0033] (In the formula, y is the rivet roll rate (‰), N is the number of arc-shaped pieces 220 of the rivet feed nozzle 22 (unitless), E is the punch force of the punch rod 3 (kN), D is the rivet head diameter (mm), L1 is the length of the rivet feed nozzle 22 (mm), L2 is the rivet length (mm), δ is the circumferential clamping stress (MPa), t is the movement tact (s) of each rivet on the belt, and k and α are both constants.) Considering the current level of processing and experience in aluminum alloy sheet metal for automobile bodies, it is common to rivet two or more layers of sheet metal using standard 3mm and 5mm rivets. The punch force of the punch rod 3 is set according to the strength and thickness of the sheet metal to be riveted, typically 60kN or 80kN, the length of the rivet feed nozzle 22 is 25-155mm, and the movement tact time of each rivet on the belt 4 is 1-3 seconds.

[0034] Based on current riveting process requirements, for example, two layers of 2.6 mm thick aluminum alloy body sheets are riveted using a 3 mm rivet. To rivet a 5.5 mm diameter, 7.2 mm long rivet, the rivet feed nozzle 22 is configured with three arc-shaped pieces 220, the length of the rivet feed nozzle 22 is set to 68.4 mm, two flexible members 23 are used to clamp the three arc-shaped pieces 220, and the circumferential clamping stress applied to the rivet by the rivet feed nozzle 22 is set to 10 MPa. Taking into account the above design requirements, the punch force of the punch rod 3 is set to 80 kN, and the belt 4 movement tact is adjusted to obtain several sets of data for the rivet rollover rate, as shown in the following table.

[0035] [Table 1]

[0036] As shown in Figure 6, curve fitting is performed using the values in the table above, and a functional relationship curve fitting model for the movement tact of each rivet on the belt 4 and the rivet rollover rate is obtained. When the values of the constants k and α are set to 0.099 and -2.97, respectively, the rivet rollover rate satisfies the following formula:

[0037]

number

[0038] As can be seen from this, when using 3mm rivets to rivet two-layer 2.6mm thick aluminum alloy body plate material, the rivet rollover rate falls below 1 / 1000 when the movement takt time of each rivet on belt 4 is 2.3 seconds. This is far superior to the rivet rollover rate of 1 / 200 for the rivet feed nozzle 22 in conventional riveting equipment, significantly reducing interruptions to the production process and rework due to rivet rollover issues and ensuring accurate riveting with all rivets.

[0039] When riveting plate materials with different strengths and thicknesses, by setting the punch force of the punch rod 3, selecting appropriate rivets and flexible members 23, and properly determining the movement tact of each rivet on the belt 4 according to the design requirements for the rivet rollover rate, the rivet rollover prevention effect of the automatic rivet rollover prevention feeder for the self-piercing riveting device of the present invention can be further optimized, ensuring that the overall performance of the riveting device is maximized and the rivet rollover rate is kept low.

[0040] The above-mentioned rivet feeding nozzle 22 is designed to be formed by connecting several arc-shaped pieces 220, which are tightly attached by the flexible member 23, thereby improving the gripping stability of the rivet feeding nozzle 22 on the rivet, making it fit better to the rivet, and reducing slippage and vibration during the rivet feeding process.

[0041] The rivet feed nozzle 22 has been improved from the conventional rigid rivet feed nozzle to one with a certain elastic deformation force, which effectively absorbs the energy generated when the rivet tilts or rolls over due to deformation of the gap between the arc-shaped pieces 220, reducing the amount of tilt or roll of the rivet and stabilizing the position and posture of the rivet. It can accommodate rivets with minor deformation or dimensional deviation, effectively reducing rollover and improving the accuracy and success rate of riveting.

[0042] 1 and 4, at least two annular passages 222 for attaching the flexible members 23 are provided around the circumferential direction of the outer wall of the rivet feed nozzle 22. The number of annular passages 222 may be two or three. The flexible members 23 are O-rings made of nitrile rubber, and at least two flexible members 23 are provided. For example, if three annular passages 222 are provided around the circumferential direction of the outer wall of the rivet feed nozzle 22, two or three flexible members 23 may be provided.

[0043] When the length L1 of the rivet feed nozzle 22 is 100 mm or less, one flexible member 23 is installed at each end of its outer wall. When the length L1 of the rivet feed nozzle 22 is greater than 100 mm, one flexible member 23 is installed in the middle of the outer wall of the rivet feed nozzle 22 for every 50 mm increase in length to improve the overall performance of the middle section of the rivet feed nozzle 22. The elasticity of the flexible members 23 allows the rivet feed nozzle 22 to have a certain gripping force on the rivet, ensuring the stability of the rivet during the feeding process and reducing misalignment due to vibration or slippage, thereby improving the accuracy and consistency of the riveting operation.

[0044] As shown in FIG. 5, the rivet feeding nozzle 22 connects three arc-shaped pieces 220 to form a guide passage 223 for pushing out the rivet.

[0045] When designing the number of arc-shaped pieces 220 of the rivet feed nozzle 22, taking into account actual production errors, it is difficult for the inner surfaces of the arc-shaped pieces 220 of the rivet feed nozzle 22 to come into uniform contact with the outer surface of the rivet head, and during the actual riveting process there are only a few contact points between each arc-shaped piece 220 and the rivet, which results in uneven circumferential clamping stress on the rivet.

[0046] When the number of arc-shaped pieces 220 of the rivet feed nozzle 22 is two, the rivet is subjected to two coaxial lateral pressures in different directions generated by the arc-shaped pieces 220, and in this case the rivet is prone to shifting or vibrating in a plane perpendicular to the rivet feed nozzle 22, and the effect of preventing the rivet from tipping over is not significant.

[0047] When the rivet feed nozzle 22 has three arc-shaped pieces 220, the rivet receives the same amount of lateral pressure in the three central directions generated by the arc-shaped pieces 220, and the principle of triangular stability allows the rivet to maintain better stability and balance within the guide passage 223. Therefore, in theory, the more arc-shaped pieces 220 there are in the rivet feed nozzle 22, the more evenly the distribution of circumferential tightening stress received by the outer periphery of the rivet head will be. However, considering production cost management, it is not good to divide the arc-shaped pieces 220 into too many pieces, and in actual production, a selection should be made that comprehensively balances the two contradictory control indicators mentioned above.

[0048] A rivet feed nozzle consisting of three arc-shaped pieces has a significantly lower rivet rollover rate than a rivet feed nozzle consisting of two arc-shaped pieces, and is relatively inexpensive compared to a rivet feed nozzle consisting of four or more arc-shaped pieces. Therefore, when considering functionality and economy, a rivet feed nozzle consisting of three arc-shaped pieces is preferred.

[0049] As shown in Figure 3, the guide joint 21 has a first bell mouth 210 on its inner wall which is larger at the top and smaller at the bottom, and the inner wall of the upper end of the rivet feed nozzle 22 where it abuts against the first bell mouth 210 forms a second bell mouth 221, and the inner diameter of the bottom end of the first bell mouth 210 is smaller than the inner diameter of the top end of the second bell mouth 221.

[0050] As shown in Figure 3, the circumferential clamping force F is composed of lateral pressures applied by several arc-shaped pieces 220 of the rivet feed nozzle 22, the lateral pressures are of the same magnitude, all directed horizontally toward the center of the rivet tip, and the number of lateral pressures is the same as the number of arc-shaped pieces 220.

[0051] The above-mentioned rivet generates an equal frictional force between itself and the contact surface of the rivet feed nozzle 22 due to the action of the circumferential clamping force F, and this frictional force keeps the rivet's balance and prevents it from shifting, and it is transported stably along the rivet feed nozzle 22 guide passage 223 to the plate to be riveted.

[0052] It should be understood that the above-described embodiments are one or more embodiments of the present invention, and there are many other embodiments and variations thereof based on the present invention. Any variations and modifications made by those skilled in the art according to the present invention without pioneering innovation fall within the scope of protection of the present invention. [Industrial Applicability]

[0053] The present invention can be advantageously used as an automatic rivet feeder that prevents rivets from tipping over for a self-piercing riveting device. [Explanation of symbols]

[0054] 1 Feeding body 10 Punched through holes 11 Horizontal passage 2 Rivet guide mechanism 21 Guide joint 210 First Bellmouth 22 Rivet feed nozzle 220 Arc-shaped piece 221 Second Bellmouth 222 Ring Road 223 Guide Passage 23 Flexible member 24 Guide tube 3 Punch Rod 4 Belt

Claims

1. An automatic rivet feeder for a riveting device, the automatic rivet feeder including a feeder body, a punch rod, and a rivet guide mechanism, a punch through hole is provided in the feed body from top to bottom, and the punch rod is inserted through the punch through hole; an upper end of the feed body is connected to a power head of a riveting device via a top end of the punch rod; a horizontal passage for transporting rivets is provided in a lower end of the feed body; a belt for transporting rivets is installed in the horizontal passage; and an end of the punch through-hole that passes vertically through the horizontal passage is connected to the rivet guide mechanism; The rivet guide mechanism includes a guide joint, a guide tube, and a rivet feed nozzle installed in the guide tube, The rivet feeding nozzle has a number of circular passages around its outer wall for attaching a flexible member, and the rivet feeding nozzle has a number of arc-shaped pieces connected together to form a guide passage for pushing out a rivet. The top end of the rivet feeding nozzle protrudes from the top end of the guide tube and abuts against the end of the punch through-hole via the guide joint; The end of the punch rod punches downward toward the rivet on the belt under the action of the power applied by the power head, applying a downward punch force E, and pushing the rivet into the end of the guide passage to fix and join the rivet to the plate to be riveted. The rivet feed nozzle formed by connecting several arc-shaped pieces applies a circumferential clamping stress δ to the rivet propelled by the punch rod to grip the rivet, and the circumferential clamping stress δ corresponds to the tightening degree of the flexible member; The length of the rivet feed nozzle is L １ The number of arc-shaped pieces of the rivet feed nozzle is N, the moving tact of each rivet on the belt is t, the head diameter of the rivet is D, and the length is L. ２ When the above formula is used to determine the rivet rollover rate y, [Equation 1] (Wherein, y is the rivet roll rate (‰), N is the number of arc-shaped pieces of the rivet feed nozzle (unitless), E is the punch force of the punch rod (kN), D is the head diameter of the rivet (mm), and L １ is the length of the rivet feed nozzle (mm), L ２ is the length of the rivet (mm), δ is the circumferential clamping stress (MPa), t is the movement tact (s) of each rivet on the belt, and k and α are both constants.

1. An automatic rivet feeder for preventing rivet overturning, for a riveting device, characterized in that

2. 2. The automatic rivet feeder for a riveting machine according to claim 1, wherein at least two annular passages for attaching flexible members are provided in the circumferential direction of the outer wall of the rivet feed nozzle.

3. 3. The automatic rivet overturn prevention feed device for a riveting machine according to claim 2, wherein two or three annular passages for attaching flexible members are provided around the outer wall of the rivet feed nozzle, the flexible members being O-rings made of nitrile rubber, and at least two flexible members are provided.

4. The automatic rivet feeder for a riveting device according to any one of claims 1 to 3, wherein the rivet feed nozzle has three arc-shaped pieces connected together to form a guide passage for pushing out the rivet.

5. 2. The automatic rivet overturn prevention feed device for a riveting machine according to claim 1, wherein the guide joint has an inner wall having a first bell mouth that is larger at the top and smaller at the bottom, the inner wall of the upper end of the rivet feed nozzle at the point where it abuts against the first bell mouth forms a second bell mouth, and the inner diameter of the bottom end of the first bell mouth is smaller than the inner diameter of the top end of the second bell mouth.

6. 2. The automatic rivet feed device for riveting equipment as set forth in claim 1, wherein the circumferential clamping force F is composed of lateral pressures applied by several arc-shaped pieces of the rivet feed nozzle, the lateral pressures having the same magnitude and all directed horizontally toward the center of the rivet tip, and the number of the lateral pressures is the same as the number of the arc-shaped pieces.

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