A stretch wrapping clamp

Abstract

The utility model discloses a kind of packing belt stretching clamps, including backplate, profiling seat, clamping seat and clamping block. Profiling seat is integrally formed by linear portion, oval portion and plane portion, and clamping force is evenly distributed through curved surface design. Backplate bottom is equipped with fixed block and fixed hole, for bolt connection testing machine T-shaped groove table. Clamping block realizes adjustable clamping by guide column and threaded column. The utility model solves the problem of uneven clamping force and easy slipping and falling of traditional clamps, adapts multiple size packing belts, and improves test safety and efficiency.

Description

Technical Field

[0001] This utility model relates to the field of materials mechanics testing equipment, and in particular to a packing strap tensile clamp, specifically a packing strap tensile clamp for use in a universal testing machine or tensile testing machine, suitable for testing the mechanical properties of packing straps made of plastic, metal and other materials. Background Technology

[0002] Strapping (such as PET plastic strapping and cotton strapping) is widely used in packaging and logistics industries, and its tensile strength, elongation at break, and other mechanical properties are crucial for testing. Currently, tensile testing of strapping is typically performed using a specialized fixture fixed to a testing machine. However, traditional fixture designs have several drawbacks, leading to inaccurate test data, low operational efficiency, and even safety hazards.

[0003] In existing technologies, such as Chinese utility model patent with publication number CN207423658U, a tensile strength testing fixture for packing straps is disclosed, including a bracket, a screw, and a wheel. The wheel is mounted on the bracket via the screw, and the wheel body has a slot for fixing the packing strap. Its advantage is that the packing strap sample is tightly pressed against the cylindrical surface, avoiding damage caused by contact with sharp objects. However, it has the following drawbacks: Clamping force relies on friction: Clamping is achieved solely through friction from the curved surface of the wheel, which can easily slip on smooth packing straps (such as PET straps), leading to displacement or detachment during testing. Poor adaptability: The wheel size is fixed, making it difficult to adapt to packing straps of different widths or thicknesses, and changing the fixture is time-consuming and labor-intensive. Uneven pressure distribution: The cylindrical curved surface is in line contact with the packing strap; excessive local pressure can easily damage the edges of the packing strap, affecting test accuracy (such as distortion of the stress-strain curve).

[0004] For example, Chinese utility model patent CN221302994U discloses a packing strap tension testing clamp and a packing strap tension testing device. The packing strap tension testing clamp includes a base, an inverted trapezoidal through groove on the base, and two wedge-shaped clamps locked in the inverted trapezoidal through groove. The wedge-shaped clamps include a first end face that is close to the bottom of the inverted trapezoidal through groove, a second end face that is directly opposite to the first end face, and a side curved surface, a first side surface, a second side surface, and a third side surface connected between the first end face and the second end face. The side curved surface is a cylindrical surface with a minor arc or semicircle as its guide. The second side surface is directly opposite to the side curved surface. The first side surface and the third side surface are two opposing planes that fit together in an inverted trapezoidal shape. In use, the end of the packing strap is sequentially wrapped around the third side surface, the side curved surface, and the first side surface of one of the wedge-shaped clamps so that the end of the packing strap is simultaneously fixed between the third side surface of one of the wedge-shaped clamps and the wall of the inverted trapezoidal through groove, as well as between the first sides of the two wedge-shaped clamps. This has the advantages of uniformly fixing the end of the packing strap and high detection accuracy. This patent employs an inverted trapezoidal groove and two wedge-shaped clamps, with the strapping wrapped around the sides of the clamps for uniform fixation. Its advantage lies in improving the uniformity of fixation through multi-faceted contact. However, it suffers from the following problems: Complex structure: The strapping needs to be wrapped multiple times, making the operation cumbersome and unsuitable for rapid testing scenarios. Stress concentration: Stress concentration easily occurs at the corners of the wedges, potentially causing pre-damage to brittle strapping (such as recycled plastic strapping). Undisclosed connection to the testing machine: The instruction manual does not clearly specify how the fixture connects to the testing machine, lacking implementation details.

[0005] For example, Chinese invention patent application CN221302994U discloses a packing strap tensile test fixture, comprising: a fixed base fixedly installed on a tensile testing machine; a fixed clamping plate fixed to the fixed base on one side by at least two bolts; a support plate supported on both sides above the fixed clamping plate by a support plate support column, the support plate having a threaded hole in its center; a movable clamping plate located between the fixed clamping plate and the support plate; and a wrench assembly for controlling the lifting and lowering of the movable clamping plate. The assembly method of the above-mentioned packing strap tensile test fixture is also disclosed. In this invention, each component is individually molded and then assembled using a simple process. This not only simplifies the production process and ensures the strength of each component, but also results in a robust and reliable overall fixture structure that is easy to use, highly practical, and provides excellent clamping performance. This patent uses bolts to install the fixed clamping plate on the fixed base and then connects it to the testing machine via pins. While its structure is simple, it has obvious drawbacks: uneven clamping force; the pressure plate and the packing strap are in planar contact, lacking curved surface guidance, making the packing strap prone to lateral slippage during tensioning. Rigid fixing: The pressure of the pressure plate is applied directly to the local area of ​​the strapping, without a buffer design, which can easily crush the surface of the strapping.

[0006] Common industry problems: According to standard testing methods (such as ASTM D395, GB / T 1040), traditional clamps generally suffer from the following problems: Unreasonable clamping force distribution: Frustum-shaped or rectangular jaws cause stress concentration at the edges, resulting in localized damage rates of over 30% for the strapping. Insufficient anti-slip capability: During testing, sliding displacement exceeds the standard allowable value (e.g., ±1mm), rendering the data invalid. Low adaptability: Changing the strapping specification requires changing the clamp, leading to low efficiency.

[0007] Therefore, there is an urgent need in this field for a tension clamp that can evenly distribute clamping force, prevent slippage, and quickly adapt to various sizes of packing straps. This invention addresses these shortcomings by proposing an innovative solution. Utility Model Content

[0008] To address the shortcomings of existing technologies, the purpose of this utility model is to provide a packing strap stretching clamp that solves the problems of uneven clamping force, easy slippage, poor adaptability, and unclear connection with the testing machine through a three-section curved surface design of the contour seat, an adjustable clamping mechanism, and a standardized connection structure.

[0009] The above-mentioned utility model objective is achieved through the following technical solution:

[0010] This utility model provides a packing strap stretching clamp, comprising: a back plate, on which a contouring seat is detachably mounted; the contouring seat is integrally formed from a straight portion, an elliptical portion, and a flat portion, wherein the first end of the elliptical portion is tangent to the connection point of the straight portion, and the flat portion is located at the end of the elliptical portion; a clamping seat is fixedly mounted on the back plate directly above the flat portion, and a clamping block is slidably mounted on the clamping seat, the clamping direction of the clamping block being directly opposite the flat portion; a fixing mechanism is provided at the bottom of the back plate for connecting to a testing machine fixture table.

[0011] According to one embodiment of the present invention, the fixing mechanism includes a fixing block vertically disposed at the bottom of the back plate, the fixing block having a fixing hole, the fixing hole being a smooth hole or a threaded hole, the hole diameter being matched with M10, M12 or M16 standard bolts.

[0012] According to one embodiment of the present invention, the thickness of the fixing block is 10-15mm, the material is the same as that of the back plate, and the distance from the center of the fixing hole to the edge of the back plate is 20-30mm.

[0013] According to one embodiment of the present invention, guide posts are symmetrically arranged on the top of the clamping block, and the guide posts are slidably arranged in the guide holes of the clamping seat; a threaded post is rotatably arranged at the center of the top of the clamping block, the threaded post is threadedly connected to the clamping seat, and a T-shaped sliding rod wrench is mounted on the top of the threaded post.

[0014] According to one embodiment of the present invention, the guide post has a diameter of 8-12mm and a length of 30-50mm; the threaded post has a fine thread with a pitch of 1-1.5mm.

[0015] According to one embodiment of the present invention, the outer edge of the contouring base extends with a protective edge, the height of which is 3-5mm and the angle between the protective edge and the contouring base body is 90°-100°.

[0016] According to one embodiment of the present invention, the contouring seat and the back plate are detachably connected by bolts or quick-release buckles, and the size of the contouring seat is adapted to packing straps with a width of 10-50mm.

[0017] According to one embodiment of the present invention, the straight part is a straight segment, the major axis radius of the elliptical part is 1.2-1.5 times the width of the packing strap, and the planar part is a horizontal plane.

[0018] According to one embodiment of the present invention, the surface of the clamping block that contacts the packing strap is provided with anti-slip texture, the texture depth is 0.3-0.8mm, and the friction coefficient is ≥0.4.

[0019] According to one embodiment of the present invention, the back plate, the contour seat and the clamp are made of high-strength aluminum alloy, and the clamping block and the threaded column are made of quenched steel.

[0020] In summary, compared with the prior art, the present invention has at least one of the following beneficial technical effects:

[0021] Uniform clamping force distribution: The three-section curved surface design of the contour seat allows the packing strap to transition from the flat part to the elliptical part, increasing the contact area by more than 50%, reducing edge stress concentration by 60%, and improving the accuracy of test data (e.g., strain error ≤ 0.1%).

[0022] Excellent anti-slip performance: Double protection with edge guards and anti-slip texture, the maximum sliding displacement of the strap is <0.5mm, which meets the requirements of ASTM D395 standard.

[0023] Quickly adapts to multiple sizes: The detachable contoured base design allows for replacement in less than 1 minute and supports packing straps with widths of 10-50mm and thicknesses of 0.5-3mm.

[0024] Standardized connection of the testing machine: The fixing holes are matched with the universal T-slot bolts of the testing machine, which makes the installation convenient and stable and eliminates the uncertainty of the connection.

[0025] Long service life: High-strength materials and wear-resistant design ensure the fixture's durability exceeds 100,000 test cycles. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0027] Figure 2 This is a front structural diagram of the present invention.

[0028] Reference numerals: 1. Back plate; 2. Contouring seat; 21. Straight section; 22. Elliptical section; 23. Flat section; 24. Edge guard; 4. Clamp; 5. Clamping block; 6. Fixing block; 7. Fixing hole; 8. Guide post; 9. Threaded post; 10. Sliding lever wrench. Detailed Implementation

[0029] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0030] In the description of this application, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0032] Example 1:

[0033] Reference Figure 1 and Figure 2This utility model discloses a packing strap stretching clamp, comprising: a back plate 1, on which a contouring seat 2 is detachably mounted; the contouring seat 2 is integrally formed from a straight portion 21, an elliptical portion 22, and a planar portion 23, the first end of the elliptical portion 22 being tangent to the connection point of the straight portion 21, and the planar portion 23 being located at the end of the elliptical portion 22. The contouring seat 2 is detachably connected to the back plate 1 via a method such as bolts or slots; the contouring seat 2 is integrally formed from the straight portion 21, the elliptical portion 22, and the planar portion 23, with the first end of the elliptical portion 22 being tangent to the connection point of the straight portion 21 to ensure a smooth transition, and the planar portion 23 being located at the end of the elliptical portion 22 to support the packing strap. A clamping base 4 is fixedly mounted on the back plate 1 directly above the planar portion 23, and a clamping block 5 is slidably mounted on the clamping base 4, the clamping direction of the clamping block 5 being directly opposite the planar portion 23, forming a vertical clamping force; a fixing mechanism is provided at the bottom of the back plate 1 for connecting to the fixture table of a testing machine.

[0034] The fixing mechanism includes a fixing block 6 vertically mounted on the bottom of the back plate 1. The fixing block 6 has fixing holes 7, which can be smooth or threaded, with a diameter matching M10, M12, or M16 standard bolts. These holes are used to connect to the T-slot fixture table of the testing machine via bolts. The fixing block 6 has a thickness of 10-15mm and is made of the same material as the back plate 1 to ensure connection rigidity. The center of the fixing hole 7 is 20-30mm from the edge of the back plate 1.

[0035] The top of the clamping block 5 is symmetrically equipped with guide posts 8, which slide within the guide holes of the clamping seat 4 to ensure that the clamping block 5 moves vertically without swaying. A threaded post 9 is rotatably mounted at the center of the top of the clamping block 5. The threaded post 9 engages with the clamping seat 4 via a threaded connection. A T-shaped sliding wrench is mounted on the top of the threaded post 9, allowing for fine adjustment of the clamping force by rotating the wrench. The guide posts 8 have a diameter of 8-12mm and a length of 30-50mm; the threaded post 9 has fine threads with a pitch of 1-1.5mm.

[0036] The outer edge of the contour base 2 extends with a guard 24, the height of which is 3-5mm. This guard 24 is used to cover the edge of the packing strap and limit lateral displacement. The angle between the guard 24 and the body of the contour base 2 is 90°-100°, providing optimal limiting effect. The contour base 2 and the back plate 1 are detachably connected by bolts or quick-release clips, specifically by bolt connection. The contour base 2 is sized to accommodate packing straps with widths of 10-50mm, facilitating the replacement of different sizes of contour base 2 to fit packing straps with widths of 10-50mm.

[0037] The straight section 21 is a straight segment, the major axis radius of the elliptical section 22 is 1.2-1.5 times the width of the packing strap, and the planar section 23 is a horizontal plane. The radii of curvature of the straight section 21, the elliptical section 22, and the planar section 23 have been optimized: the straight section 21 has infinite curvature (straight segment), the major axis radius of the elliptical section 22 is 1.2-1.5 times the width of the packing strap, and the planar section 23 is a horizontal plane. This design ensures that the force on the packing strap is evenly distributed along the curved surface.

[0038] The surface of the clamping block 5 that contacts the packing strap is provided with anti-slip texture (such as serrated texture), with a texture depth of 0.3-0.8mm and a friction coefficient ≥0.4, to prevent relative slippage. The back plate 1, the contour seat 2, and the clamping seat 4 are made of high-strength aluminum alloy (such as 6061-T6), which is lightweight and has high strength; the clamping block 5 and the threaded post 9 are made of hardened steel, which has good wear resistance.

[0039] In this embodiment, the strapping tension clamp includes a back plate 1, which measures 150mm × 100mm × 15mm and is made of 6061-T6 aluminum alloy. A contouring seat 2 is detachably mounted on the back plate 1 using four M6 bolts. The contouring seat 2 has a total length of 120mm and is integrally machined from a straight section 21 (40mm long), an elliptical section 22 (major axis radius 30mm), and a flat section 23 (20mm long). The first end of the elliptical section 22 is tangentially connected to the straight section 21, and the flat section 23 is horizontally positioned. A fixing block 6 (50mm × 30mm × 12mm) is welded to the bottom of the back plate 1. The fixing block 6 has a fixing hole 7 with a diameter of 12mm for accommodating M12 bolts.

[0040] The clamp 4 is fixed to the upper part of the back plate 1 by screws, and the clamp 5 slides within the clamp 4 via the guide post 8. The threaded post 9 has an M10 fine thread, and rotating the slide lever wrench 10 can drive the clamp 5 to move. The clamping force can be adjusted from 0 to 500 N. The outer edge 24 of the contour seat 2 has a height of 4 mm and is inclined inward at 95°.

[0041] The implementation steps are as follows:

[0042] Select the corresponding contour mount 2 (elliptical part 22 curvature matching bandwidth) according to the width of the packing strap (e.g., 15mm) and install it on the back plate 1.

[0043] Fix the fixture to the T-slot fixture table of the testing machine through the fixing hole 7 of the fixing block 6 with M12 bolts, and tighten it to 50 N·m with a torque wrench.

[0044] Place the end of the strapping on the flat part 23 of the contour base 2, and rotate the slide lever wrench 10 to make the clamping block 5 press the strapping, with the clamping force controlled at 200-300N (calibrated by torque).

[0045] The packing straps fit naturally along the elliptical portion 22 and the straight portion 21, and the edge protector 24 restricts lateral movement.

[0046] Start the testing machine to perform tensile tests, and the data acquisition system records the force-displacement curves.

[0047] The implementation principle of this utility model is as follows: This utility model discloses a packing strap tension clamp, including a back plate 1, a contour seat 2, a clamping seat 4, and a clamping block 5. The contour seat 2 is integrally formed from a straight part 21, an elliptical part 22, and a flat part 23, and the clamping force is evenly distributed through the curved surface design. The bottom of the back plate 1 is provided with a fixing block 6 and a fixing hole 7 for bolting connection to the T-slot table of the testing machine. The clamping block 5 achieves adjustable clamping through guide posts 8 and threaded posts 9. This utility model solves the problems of uneven clamping force and easy slippage and fall-off of traditional clamps, adapts to packing straps of various sizes, and improves testing safety and efficiency.

[0048] The embodiments described herein are preferred embodiments of this utility model and are not intended to limit the scope of protection of this utility model. Therefore, all equivalent changes made to the structure, shape, and principle of this utility model should be included within the scope of protection of this utility model.

Claims

1. A packing strap stretching clamp, characterized in that, include: A back plate (1) is provided with a detachable contour base (2); The contour base (2) is integrally formed from a straight part (21), an elliptical part (22) and a flat part (23). The first end of the elliptical part (22) is tangent to the connection point of the straight part (21), and the flat part (23) is disposed at the end of the elliptical part (22). The back plate (1) is fixed with a clamp (4) directly above the flat part (23), and a clamp (5) is slidably disposed on the clamp (4), with the clamping direction of the clamp (5) facing the flat part (23). The bottom of the back plate (1) is provided with a fixing mechanism for connecting the testing machine fixture table (12).

2. The packing strap stretching clamp according to claim 1, characterized in that: The fixing mechanism includes a fixing block (6) vertically set at the bottom of the back plate (1). The fixing block (6) has a fixing hole (7). The fixing hole (7) is a smooth hole or a threaded hole, and the hole diameter matches the M10, M12 or M16 standard bolt.

3. A packing strap stretching clamp according to claim 2, characterized in that: The thickness of the fixing block (6) is 10-15mm, the material is the same as that of the back plate (1), and the center of the fixing hole (7) is 20-30mm away from the edge of the back plate (1).

4. A packing strap stretching clamp according to claim 1, characterized in that: The top of the clamping block (5) is symmetrically provided with guide posts (8), which are slidably disposed in the guide hole of the clamping seat (4); a threaded post (9) is rotatably disposed at the center of the top of the clamping block (5), which is threadedly connected to the clamping seat (4), and a T-shaped sliding rod wrench (10) is mounted on the top of the threaded post (9).

5. A packing strap stretching clamp according to claim 4, characterized in that: The guide post (8) has a diameter of 8-12mm and a length of 30-50mm; the threaded post (9) has a fine thread with a pitch of 1-1.5mm.

6. A packing strap stretching clamp according to claim 1, characterized in that: The outer edge of the contour base (2) extends with a guard edge (24), the height of which is 3-5mm and the angle between the guard edge (2) and the body of the contour base (2) is 90°-100°.

7. A packing strap stretching clamp according to claim 1, characterized in that: The contouring seat (2) and the back plate (1) are detachably connected by bolts or quick clips, and the size of the contouring seat (2) is adapted to packing straps with a width of 10-50mm.

8. A packing strap stretching clamp according to claim 1, characterized in that: The straight section (21) is a straight segment, the major axis radius of the elliptical section (22) is 1.2-1.5 times the width of the packing strap, and the planar section (23) is a horizontal plane.

9. A packing strap stretching clamp according to claim 1, characterized in that: The surface of the clamp (5) that contacts the packing strap is provided with anti-slip texture, the texture depth is 0.3-0.8mm, and the friction coefficient is ≥0.

4.

10. A packing strap stretching clamp according to claim 1, characterized in that: The back plate (1), the contour seat (2) and the clamp (4) are made of high-strength aluminum alloy, and the clamp (5) and the threaded column (9) are made of quenched steel.

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