A self-locking structure for the plastic casing of a trimming machine

Abstract

The present invention relates to the technical field of trimming machine devices and relates to a self-locking structure for a plastic casing of a trimming machine. The present invention is arranged on the casing, and a screw head shaft is provided on the casing, and a circular hole is provided at the side end of the screw head shaft, and a positioning block is provided at the upper end of the casing. A connected pin guide hole and a circular cavity are provided inside the positioning block, and the inner diameter of the circular cavity is larger than the inner diameter of the pin guide hole. An insert is provided inside the pin guide hole, and a button is provided inside the circular cavity. A spring groove is provided inside the button, and a spring is provided in the spring groove. A self-locking shaft is provided inside the inner hole of the insert, and one end of the self-locking shaft is provided in the button, and the self-locking shaft is coaxially arranged with the circular hole. The self-locking shaft includes a clamping part, an intermediate part and a pre-tightening part, and an insert is added inside the positioning block. The inner hole of the insert serves as a guide hole for the self-locking shaft, so that the self-locking shaft does not directly contact the pin guide hole of the positioning block, so that the pin guide hole will not be deformed into a waist-shaped hole after long-term use.

Description

Technical Field

[0001] The invention relates to the technical field of trimmer devices, in particular to a self-locking structure for a plastic casing of a trimmer. Background Art

[0002] The existing trimming machine with a self-locking structure consists of a spring, a self-locking shaft and a button. The specific assembly steps are to install the self-locking shaft into the pin guide hole on the casing, install the spring into the cylinder inside the button, and then install the button with the spring into the circular cavity on the casing. Finally, use the tooling to press the conical head on the self-locking shaft onto the button. The specific way to lock the shaft is to press one end of the self-locking shaft into the circular hole on the shaft after holding the button with your hand, so that the shaft cannot rotate to achieve the purpose of locking the shaft. Then, you can use a wrench to tighten and loosen the nut on the shaft. In the process of tightening and loosening the nut head, the wrench will give the self-locking device a reverse torque. The current locking torque is generally required to be 11Nm, and the destructive torque that the self-locking device can withstand should be ≥27.5Nm. Currently, this structure is only suitable for metal casings. When tightening the wrench, the self-locking pin will be subjected to a reverse force, causing the pin guide hole to deform into a waist-shaped hole due to long-term use. In addition, due to the insufficient strength of the plastic casing, after long-term use, when the wrench reaches a locking force of 20Nm, the plastic casing above the self-locking pin will crack, causing the self-locking device to fail.

[0003] In summary, in order to solve the problems in the prior art, it is necessary to design a self-locking structure suitable for the plastic casing of the trimming machine. Summary of the Invention

[0004] In order to solve the problems of the prior art, the present invention provides a self-locking structure for a trimmer.

[0005] The purpose of the present invention can be achieved through the following technical solutions: a self-locking structure for a trimming machine, which is arranged on a casing, a screw head shaft is provided on the casing, a nut is provided at the upper end of the screw head shaft, a circular hole is provided at the side end of the screw head shaft, a positioning block is provided at the upper end of the casing, a pin guide hole and a circular cavity are provided in communication inside the positioning block, the inner diameter of the circular cavity is larger than the inner diameter of the pin guide hole and the circular cavity is provided outside the pin guide hole, an insert is provided inside the pin guide hole, a button is provided inside the circular cavity, a spring groove is provided inside the button, and a spring is provided in the spring groove. A self-locking shaft is provided inside the inner hole of the insert, one end of the self-locking shaft is provided in the button, and the self-locking shaft is coaxially arranged with the circular hole. The self-locking shaft includes a clamping part, an intermediate part and a pre-tightening part. The outer diameter of the pre-tightening part is larger than the outer diameter of the intermediate part, and the outer diameter of the pre-tightening part is larger than the inner hole diameter of the insert. The diameter D1 of the pre-tightening part is 5.8 mm, the length L1 of the pre-tightening part is 4.0 mm, the length L2 of the intermediate part is 11.9 mm, the distance L3 between the left end face of the button and the left end face of the circular cavity is 4.6 mm, and the gap width L4 between the pre-tightening part and the circular hole is 0.25 mm.

[0006] As a further improvement, the self-locking shaft is connected to the button in an inverted manner.

[0007] As a further improvement, the insert is injection-molded and embedded in the pin guide hole.

[0008] As a further improvement, a tool-retraction groove is provided at the connection between the middle portion and the pre-tightening portion.

[0009] As a further improvement, the insert is made of copper.

[0010] Compared with the prior art, the present invention incorporates an insert within the positioning block in the self-locking structure of a trimming machine. The inner hole of the insert serves as a guide hole for the self-locking shaft, preventing the self-locking shaft from directly contacting the pin guide hole of the positioning block. This prevents the pin guide hole from deforming into a waist-shaped hole after long-term use. Changes in the internal dimensions of the self-locking shaft and the positioning block do not affect the overall structure and assembly of the self-locking shaft. This allows the self-locking device, which previously could only withstand a 20 Nm breaking torque on a plastic housing, to withstand a breaking torque of over 30 Nm, meeting the strength requirements for use. This higher breaking torque makes it suitable for trimming machines with plastic housings, preventing the plastic housing from cracking due to the increased self-locking force. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic structural diagram of the present invention

[0012] Figure 2 Schematic diagram of the internal structure of the screw machine head shaft when it is not fixed

[0013] Figure 3 Schematic diagram of the internal structure of the screw machine head with the shaft fixed

[0014] Figure 4 Schematic diagram of the structure of the self-locking shaft in the present invention

[0015] In the figure, 1- housing, 11- screw head shaft, 12- nut, 13- round hole, 2- positioning block, 21- pin guide hole, 22- circular cavity, 3- insert, 31- inner hole, 4- button, 41- spring groove, 5- spring, 6- self-locking shaft, 61- clamping part, 62- middle part, 63- pre-tightening part, 64- tool withdrawal groove. DETAILED DESCRIPTION

[0016] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0017] In the description of the present invention, it should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0018] Below with reference to the embodiment and the attached Figures 1 to 4 , further elaborating on the technical solution of the present invention.

[0019] Example 1

[0020] A self-locking structure for a plastic casing of a trimming machine is provided on a casing 1, wherein a screw head shaft 11 is provided on the casing 1, a nut 12 is provided at the upper end of the screw head shaft 11, and a circular hole 13 is provided at the side end of the screw head shaft 11, characterized in that a positioning block 2 is provided at the upper end of the casing 1, a pin guide hole 21 and a circular cavity 22 are provided in communication inside the positioning block 2, the inner diameter of the circular cavity 22 is larger than the inner diameter of the pin guide hole 21 and the circular cavity 22 is provided on the outside of the pin guide hole 21, an insert 3 is provided inside the pin guide hole 21, a button 4 is provided inside the circular cavity 22, a spring slot 41 is provided inside the button 4, a spring 5 is provided in the spring slot 41, and the A self-locking shaft 6 is provided inside the inner hole 31 of the insert 3, one end of the self-locking shaft 6 is provided in the button 4, and the self-locking shaft 6 is coaxially arranged with the circular hole 13. The self-locking shaft 6 includes a clamping portion 61, an intermediate portion 62 and a pre-tightening portion 63. The outer diameter of the pre-tightening portion 63 is greater than the outer diameter of the intermediate portion 62, and the outer diameter of the pre-tightening portion 63 is greater than the inner hole diameter of the insert 3. The diameter D1 of the pre-tightening portion 63 is 5.8 mm, the length L1 of the pre-tightening portion 63 is 4.0 mm, the length L2 of the intermediate portion 62 is 11.9 mm, the distance L3 between the left end face of the button 4 and the left end face of the circular cavity 22 is 4.6 mm, and the gap width L4 between the pre-tightening portion 63 and the circular hole 13 is 0.25 mm.

[0021] Usage process: The self-locking shaft 6 is installed into the pin guide hole 21 of the positioning block 2, the spring 5 is installed into the spring groove 41 inside the button 4, and then the button 4 equipped with the spring is installed into the circular cavity 22 of the positioning block 2. Finally, the tool is used to press the home step 61 on the self-locking shaft into the button 4. Continue to push the button 4 inward into the circular cavity 22 with one hand until the pre-tightening part 63 of the self-locking shaft 6 is pushed into the circular hole 13 of the screw head shaft 11, so that the screw head shaft 11 cannot rotate to achieve the purpose of locking the shaft. Then, the nut 12 on the screw head shaft 11 can be tightened and loosened with a wrench. After tightening and loosening, the self-locking shaft 6 can move outward under the rebound action of the spring to release the lock on the screw head shaft 11.

[0022] An insert 3 is added inside the positioning block 2, and the inner hole 31 of the insert 3 serves as a guide hole for the self-locking shaft 6, so that the self-locking shaft 6 does not directly contact the pin guide hole 21 of the positioning block 2, so that the pin guide hole 21 will not be deformed into a waist-shaped hole under long-term use.

[0023] While the diameter of the circular hole 13 of the screwdriver shaft 11 remains unchanged at 6.3 mm, the dimensions of the self-locking shaft 6 are modified: the diameter D1 of the pre-tightening portion 63 of the self-locking shaft is changed from 5.0 mm to 5.8 mm, the length L1 of the pre-tightening portion 63 of the self-locking shaft is changed from 3.0 mm to 4.0 mm, the length L2 of the middle portion 62 of the self-locking shaft is changed from 9.9 mm to 11.9 mm, and the distance L3 between the left end face of the button 4 in the self-locking shaft and the left end face of the circular cavity 22 is changed from 2.6 mm to 4.6 mm. This increases the insertion stroke of the self-locking shaft 6, and the width L4 of the gap between the pre-tightening portion 63 of the self-locking shaft 6 and the circular hole 13 is changed from 0.65 mm to 0.25 mm. This increases the load-bearing area of ​​the self-locking shaft. These dimensional changes significantly enhance the force that the self-locking device can withstand when a wrench is tightened on the nut 12 of the screwdriver shaft 11.

[0024] The following is the test data of the ultimate breaking torque after the size was modified: a total of 5 groups.

[0025] The first group: 33.42Nm; the second group: 32.68Nm; the third group: 31.94Nm; the fourth group:

[0026] 31.57Nm; Group 5: 36.25Nm

[0027] According to the above data, it can be concluded that the force that can be borne has increased from 20Nm to 30Nm (greater than the required 27.5Nm), thus meeting the use requirements.

[0028] These dimensional changes do not affect the overall self-locking shaft's structure and assembly. While the original self-locking mechanism could only withstand a breaking torque of 20 Nm on a plastic housing, it now withstands a breaking torque of over 30 Nm, meeting the required strength for use. This increased breaking torque makes it suitable for trimming machines used on plastic housings, preventing the housing from cracking due to the increased self-locking force.

[0029] As a further embodiment, the self-locking shaft 6 is invertedly connected to the button 4. The inverted connection is convenient for installation.

[0030] As a further embodiment, the insert 3 is injection-molded and embedded in the pin guide hole 21, so that the connection is more stable.

[0031] As a further embodiment, a back-off groove 64 is provided at the connection between the middle portion 62 and the pre-tightening portion 63. Figure 2 As shown, it is ensured that the right end face of the pre-tightening portion 63 of the self-locking shaft 6 is processed in place and is tightly fitted with the left end face of the insert 3. The self-locking shaft 6 slides smoothly when locked and released back and forth without any jamming.

[0032] As a further embodiment, the material of the insert 3 is copper, which increases the hardness of the insert 3 and prolongs its service life.

[0033] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A self-locking structure for a plastic casing of a trimming machine, which is arranged on the casing, wherein a screw head shaft is provided on the casing, a nut is provided at the upper end of the screw head shaft, and a circular hole is provided at the side end of the screw head shaft, characterized in that: The upper end of the casing is provided with a positioning block, and a connected pin guide hole and a circular cavity are provided inside the positioning block. The inner diameter of the circular cavity is larger than the inner diameter of the pin guide hole and the circular cavity is arranged on the outside of the pin guide hole. An insert is provided inside the pin guide hole, and a button is provided inside the circular cavity. A spring groove is provided inside the button, and a spring is provided in the spring groove. A self-locking shaft is provided inside the inner hole of the insert, and one end of the self-locking shaft is provided in the button. The self-locking shaft is coaxial with the circular hole. The self-locking shaft includes a clamping portion, an intermediate portion and a pre-tightening part, the outer diameter of the pre-tightening part is larger than the outer diameter of the middle part, the outer diameter of the pre-tightening part is larger than the inner hole diameter of the insert, the diameter D1 of the pre-tightening part is 5.8mm, the length L1 of the pre-tightening part is 4.0mm, the length L2 of the middle part is 11.9mm, the distance L3 between the left end face of the button and the left end face of the circular cavity is 4.6mm, the gap width L4 between the pre-tightening part and the circular hole is 0.25mm, the insert is injection-molded and embedded in the pin guide hole, the self-locking shaft is invertedly connected to the button, and the material of the insert is copper.

2. The self-locking structure for the plastic casing of a trimming machine according to claim 1, characterized in that: A cutter recess is provided at the connection between the middle portion and the pre-tightening portion.

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