Hedge trimmer blade protector with steel ball scratch-proof structure

Abstract

The invention discloses a hedge trimmer blade protector with a steel ball scratch-proof structure, the blade protector comprises a metal frame, an upper stationary knife, a lower stationary knife and a mounting plate which are integrally welded, and the hedge trimmer blade protector is characterized in that a steel ball is welded at the foremost end of the blade protector and is used for guiding branches to slide into a cutting gap, and branch fibers are prevented from being scratched by tip ends. The gap between the upper fixed cutter and the lower fixed cutter is precisely controlled through machining after welding, and cutting precision is guaranteed. The whole blade protector is quenched, so that the hardness and the wear resistance are improved. The device has the advantages of being simple in structure, convenient to install, high in cutting precision, small in fiber damage, long in service life and the like.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery technology, specifically to a blade protector for a hedge trimmer with a steel ball anti-scratch structure. Background Technology

[0002] Hedge trimmers are commonly used equipment in garden maintenance. Their core component, the guard blade, uses a fixed blade to cut branches, achieving shaping and trimming of hedges. Existing guard blades are typically made of castings or welded parts, with a semi-open structure. Only the lower fixed blade is present; the moving blade, constrained by the pressure plate, cuts the branch inserted between the two tips of the guard blade. However, this design has the following drawbacks: (1) Severe fiber damage: The tip of the blade guard has a sharp edge, which can easily scrape the surface of the branches directly during the movement of the pruning machine, damaging the phloem fibers, resulting in slow healing of branches and trunks and easy infection with diseases (such as rot). (2) Insufficient cutting precision: The gap between the lower fixed blade and the pressure blade has not been precisely machined, which can easily lead to problems such as too large a gap (resulting in incomplete cutting of branches and residual stubble) or too small a gap (resulting in branches being squeezed and torn). (3) Limited durability: The blade guard is prone to wear due to long-term friction with branches, and if the overall strength of the blade guard is insufficient, it is easy to break or deform due to impact from branches, which affects the cutting effect. Therefore, a blade guard structure that can protect the branch fibers and improve cutting accuracy and durability is needed. Summary of the Invention

[0003] The purpose of this invention is to provide a hedge trimmer blade protector with a steel ball anti-scratch structure to solve the problems of branch fiber damage, low cutting accuracy and poor durability in the prior art.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a hedge trimmer blade guard with a steel ball anti-scratch structure, comprising a mounting plate, an upper fixed blade, and a lower fixed blade. Its innovation lies in: the blade guard is an integrally welded metal frame, and a steel ball is welded to the front end of the upper fixed blade; the cutting gap between the upper fixed blade and the lower fixed blade is formed by machining after the metal frame is welded.

[0005] Furthermore, the diameter of the steel ball is 10mm to 20mm.

[0006] Furthermore, the diameter of the steel ball is 15mm, with a tolerance of ±0.1mm.

[0007] Furthermore, the steel ball is made of 45# steel.

[0008] Furthermore, the steel ball is welded to the front end of the upper fixed blade by gas shielded welding, and the weld leg thickness at the weld is not less than 2mm.

[0009] Furthermore, the width of the cutting gap is 4.5 mm, with a tolerance of ±0.1 mm.

[0010] Furthermore, the metal frame as a whole undergoes quenching and tempering heat treatment, and its surface hardness is HRC 45 to HRC 55.

[0011] Furthermore, the surface hardness is HRC 50 to HRC 55.

[0012] Furthermore, the mounting plate is made of Q235 steel plate with a thickness of 5mm; the upper and lower fixed blades are made of 65Mn steel strip with a thickness of 5mm.

[0013] Furthermore, the blade guard is a double-blade or triple-blade structure, suitable for cutting branches with a diameter of no more than 30mm.

[0014] With the above structure, the beneficial effects of the present invention are as follows: Superior protection against tree branches and fibers: By incorporating a steel ball at the very tip of the blade guard, the contact between the guard and the branch is fundamentally transformed from the existing "sharp scratching" to "circular rolling guidance." The rounded surface of the steel ball smoothly guides the branch into the cutting area, effectively preventing the sharp tip of the guard from directly scratching the phloem fibers of the branch. This design reduces the rate of fiber scratches on the branch surface by more than 90%, greatly reducing the pathways for pathogen infection and promoting rapid healing and healthy growth of the pruned branches.

[0015] High cutting precision and neat trimmed surface: Utilizing a "welding followed by precision machining" process, the guard frame is first welded together, and then the cutting gap between the upper and lower fixed blades is machined in one step using precision equipment such as a milling machine. This method fundamentally eliminates the problem of uneven gaps caused by split structures or welding deformation, ensuring the cutting gap (4.5mm ± 0.1mm) is precise and consistent throughout its entire length. This allows branches to be cut cleanly and evenly under uniform force, virtually eliminating the squeezing, tearing, and residue of branch stubs (residual length can be controlled to ≤2mm), thus significantly improving the smoothness and aesthetics of the trimmed hedge surface.

[0016] The overall structure has good rigidity and a long service life. Structural aspects: The one-piece welded metal frame avoids the problem of loose connections in split structures, significantly enhancing overall rigidity and impact resistance, effectively resisting the impact of tree branches, and preventing the guard from deforming or breaking during operation.

[0017] In terms of materials: the entire blade guard undergoes quenching and tempering heat treatment, achieving a surface hardness of HRC 50-55 for the fixed blade and key components, significantly improving its wear resistance and fatigue strength. Practical experience has shown that this design increases the wear resistance of the blade guard by more than 30%, greatly extending its service life and reducing the frequency of replacement and maintenance.

[0018] High efficiency and versatility: This invention can adopt a double or triple fixed blade structure design, enabling simultaneous cutting of multiple branches and significantly improving the efficiency of a single pruning operation. The blade guard is designed as a universal component; it can be easily installed as long as its installation dimensions match the blade beam of the pruning machine. It is suitable for pruning various hedge plants with a diameter of less than 30mm, and has a wide range of applications. Attached Figure Description

[0019] Figure 1 This is a 3D structural diagram of the blade guard of the present invention; Figure 2 A schematic diagram showing the contact between the steel ball at the tip of the blade guard and a tree branch; Figure 3 This is a cross-sectional view of the blade guard.

[0020] Explanation of reference numerals in the attached figures: 1-Mounting plate, 2-Upper fixed blade, 3-Gap between upper and lower fixed blades, 4-Lower fixed blade, 5-Steel ball, 6-Tree branch, 7-Arc guide surface. Detailed Implementation

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0023] I. Structure and Material Preparation refer to Figures 1 to 3 The blade guard in this embodiment mainly includes the following components: Mounting plate 1: Made of 5mm thick Q235 steel plate, formed by laser cutting, with mounting holes for fixing the entire guard to the trimmer blade beam.

[0024] Upper fixed blade 2 and lower fixed blade 4: Made of 5mm thick 65Mn spring steel strip. First, the blade shape and mounting holes are laser-cut, and then a special mold is used for molding to ensure the straightness and shape accuracy of the blade edge.

[0025] Steel ball 5: Use a standard 45# steel ball with a diameter of 15mm±0.1mm. Its surface finish must reach Ra 3.2 or higher to ensure good sliding guidance effect.

[0026] II. Welding Forming Process Assembly and Positioning: Place the prefabricated mounting plate 1, upper fixed blade 2, and lower fixed blade 4 into a dedicated welding fixture in sequence. This fixture can accurately ensure that the initial parallel distance between the upper and lower fixed blades is 3.5mm, and ensure that the mounting hole of the upper fixed blade 2 is concentric with the mounting hole of the mounting plate 1.

[0027] Frame welding: The above components are welded into a rigid, integrated metal frame using gas carbon dioxide shielded welding (GC-MAG). Welding should be continuous and uniform, with the weld strength required to be no less than 80% of the base material strength. Heat input must be controlled during the welding process to minimize welding deformation.

[0028] III. Precision Machining Fixed-blade clearance machining: Securely fix the welded one-piece frame onto the worktable of the vertical milling machine. Using a finishing end mill with a diameter smaller than the width of the fixed blades, mill the cutting gap 3 between the upper fixed blade 2 and the lower fixed blade 4 in one pass. Through CNC programming or precision scale control, precisely machine the gap 3 from the initial 3.5mm to a final size of 4.5mm ± 0.1mm. This step is crucial to ensuring cutting accuracy and preventing branches from being squeezed or torn.

[0029] IV. Steel Ball Welding Positioning: On the arc-shaped guide surface at the foremost end of the upper fixed blade 2, the welding center position of the steel ball 5 is precisely marked using scribing or laser marking.

[0030] Welding: Place steel ball 5 at the marked position and weld using gas shielded welding. Use a low current and short arc welding method to prevent the steel ball from annealing or deforming due to overheating. Ensure the weld penetration is at least 2mm to prevent the steel ball 5 from falling off when subjected to impacts from tree branches during operation. After welding, inspect the arc surface of steel ball 5 to ensure there is no weld slag adhering to it and no obvious deformation.

[0031] V. Heat Treatment Strengthening The entire blade guard, after all welding and machining are completed, is sent to a heat treatment furnace for strengthening treatment: Quenching: Heating in a high-frequency quenching furnace at 850℃ for 30 seconds to fully austenitize the surface and core of the workpiece, followed by rapid oil quenching.

[0032] Tempering: Immediately place the quenched workpiece into a tempering furnace at 200℃ and hold for 2 hours, then air cool to room temperature. This heat treatment process enables the entire blade guard, especially the fixed blade made of 65Mn material, to achieve a surface hardness of HRC 50-55, significantly improving its wear resistance and impact toughness.

[0033] VI. Work Process like Figure 2 As shown, when the hedge trimmer equipped with this guard moves forward, the steel ball 5 at the very tip of the guard first contacts the branch 6. The arc-shaped guide surface 7 of the steel ball 5 transforms the sliding contact into rolling guidance, allowing the branch 6 to smoothly slide along the surface of the steel ball into the cutting gap 3 between the upper fixed blade 2 and the lower fixed blade 4. Subsequently, the moving blade of the trimmer (not shown in the figure, with a gap of 1.5mm between it and the lower fixed blade) forms a shearing motion with the lower fixed blade 4 under power drive, cleanly and neatly cutting the branch. Throughout the process, the steel ball 5 effectively prevents the sharp tip of the guard from directly scratching the surface fibers of the branch, achieving protective cutting. After cutting, the steel ball 5 continues to guide the guard to move to the next branch to be trimmed, and the cycle repeats.

[0034] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A hedge trimmer blade guard with a steel ball anti-scratch structure, comprising a mounting plate, an upper fixed blade, and a lower fixed blade, characterized in that: The blade guard is a one-piece welded metal frame, with a steel ball welded to the front end of the upper fixed blade; the cutting gap between the upper and lower fixed blades is formed by machining after the metal frame is welded.

2. The hedge trimmer blade guard with steel ball anti-scratch structure according to claim 1, characterized in that: The diameter of the steel ball is 10mm to 20mm.

3. The hedge trimmer blade guard with steel ball anti-scratch structure according to claim 2, characterized in that: The steel ball has a diameter of 15mm and a tolerance of ±0.1mm.

4. The hedge trimmer blade guard with steel ball anti-scratch structure according to claim 1, characterized in that: The steel ball is made of 45# steel.

5. The hedge trimmer blade guard with steel ball anti-scratch structure according to claim 1, characterized in that: The steel ball is welded to the front end of the upper fixed blade by gas shielded welding, and the thickness of the weld leg at the weld is not less than 2mm.

6. The hedge trimmer blade guard with steel ball anti-scratch structure according to claim 1, characterized in that: The width of the cutting gap is 4.5 mm, with a tolerance of ±0.1 mm.

7. The hedge trimmer blade guard with steel ball anti-scratch structure according to claim 1, characterized in that: The metal frame is subjected to quenching and tempering heat treatment, and its surface hardness is HRC 45 to HRC 55.

8. The hedge trimmer blade protector with steel ball anti-scratch structure according to claim 7, characterized in that: The surface hardness is HRC 50 to HRC 55.

9. The hedge trimmer blade guard with steel ball anti-scratch structure according to claim 1, characterized in that: The mounting plate is made of Q235 steel plate with a thickness of 5mm; the upper and lower fixed blades are made of 65Mn steel strip with a thickness of 5mm.

10. The hedge trimmer blade guard with steel ball anti-scratch structure according to claim 7, characterized in that: The blade guard is a double-blade or triple-blade structure, suitable for cutting branches with a diameter of no more than 30mm.

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