Medical gypsum saw and design method thereof

Abstract

The invention provides a medical gypsum saw and a design method thereof, and the medical gypsum saw comprises a swing head assembly, a positioning seat and a main body which are sequentially connected along the Y direction; the saw blade is arranged on the saw blade shaft and located outside the swing head assembly, the saw blade shaft is rotationally installed in the swing head assembly, and the section, facing the main body, of the saw blade shaft, the saw blade shaft seat and the driven ball are sequentially connected. A preset distance in the X direction is formed between the driven ball and the axis of the saw blade shaft. The driven ball makes contact with the two side walls of an annular groove formed in the disc, and a rotating gap is formed between the driven ball and the inner wall of the swing head assembly. The disc is sleeved on the fixed pin, and the fixed pin is fixed on the swinging head assembly and extends along the X direction; the driving ball is eccentrically arranged at the tail end of the motor shaft and makes contact with the two side walls of the annular groove formed in the disc. The motor shaft is rotationally arranged on the positioning seat and extends into the main body along the Y direction; the axis of the motor shaft and the axis of the saw blade shaft are coaxially arranged. The main body is coaxial with the axis of the saw blade shaft, so that the operation sight of a doctor is not blocked.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical devices, and particularly relates to a medical plaster saw and its design method. Background Art

[0002] Plaster saws are used to remove the plaster fixed on the limbs of patients after the recovery from diseases such as fractures. In existing plaster saws, since the arrangement of the holding handle and the saw blade shaft presents a large parallel distance, the saw body is large, resulting in the doctor's line of sight being easily blocked when holding it, and it is impossible to cut a specific area (such as the inside of a bent arm). To solve the above problems, a special eccentric ball swing type plaster saw is invented, in which the holding handle and the saw blade installation axis are coaxial, without blocking the doctor's operation line of sight. Summary of the Invention

[0003] The purpose of the present invention is to provide a medical plaster saw and its design method, in which the holding handle of the swing saw and the axis of the saw blade installation shaft are coaxial, without blocking the doctor's operation line of sight. The technical solution adopted is as follows: A medical plaster saw, comprising: A swing head assembly 13, a positioning seat and a main body 1, which are sequentially connected along the Y direction; A saw blade 12, which is arranged on a saw blade shaft 11 and located outside the swing head assembly 13. The saw blade shaft 11 is rotatably installed in the swing head assembly 13. A section of the saw blade shaft 11 facing the main body 1, a saw blade shaft seat 10 and a driven ball 9 are sequentially connected. A preset distance along the X direction is formed between the axis of the driven ball 9 and the saw blade shaft 11. The driven ball 9 contacts the two side walls of the annular groove formed on the disc 6, and a rotation gap is formed between the driven ball 9 and the inner wall of the swing head assembly 13; The disc 6 is used to drive the driven ball 9 to rotate around the axis of the saw blade shaft 11. It is sleeved on a fixed pin 8, and the fixed pin 8 is arranged on the swing head assembly 13 and extends along the X direction; And a driving ball 5, which is eccentrically arranged at the end of the motor shaft 4 and contacts the two side walls of the annular groove formed on the disc 6. The motor shaft 4 is rotatably arranged on the positioning seat and extends along the Y direction into the main body 1. The motor corresponding to the motor shaft 4 is arranged in the main body 1; The axis of the motor shaft 4 and the axis of the saw blade shaft 11 are coaxially arranged.

[0004] Preferably, the swing head assembly 13 includes: A first installation channel and a second installation channel that extend along the Y direction and are connected. The first installation channel is used to install the saw blade shaft 11 and is open at one end facing the saw blade 12. The second installation channel is used to install the saw blade shaft seat 10, the driven ball 9 and the disc 6; And a pin hole that extends along the X direction and is used to install the fixed pin 8. The fixed pin 8 is in interference fit with the pin hole. The pin hole communicates with the second installation channel.

[0005] Preferably, a first bearing cover, a first bearing, a transition cylinder, a second bearing, and a second bearing cover are sequentially arranged in the first installation channel; The first bearing cover is in interference fit with the swing head assembly 13. The second bearing cover is placed on a step formed between the first installation channel and the second installation channel. One end of the saw blade shaft 11 is located outside the first bearing cover, and the other end sequentially passes through the first bearing, the transition cylinder, the second bearing, and the second bearing cover and extends toward the second installation channel.

[0006] Preferably, a third installation channel corresponding to the second installation channel and for installing the motor shaft 4 is provided in the positioning seat; A sealing ring is clamped on the inner wall of the third installation channel. A third bearing is clamped in the sealing ring, and the third bearing is placed on a shaft shoulder on the motor shaft 4.

[0007] Preferably, an axial fixing piece 7 is clamped between the second installation channel and the disc 6. The fixing pin 8 passes through the axial fixing piece 7. Both pairs of the axial positioning pieces 7 are in contact with the disc 6. One side of the axial fixing piece 7 facing the disc 6 is a plane to be adapted to the disc 6.

[0008] Preferably, the saw blade shaft 11 is clamped in the saw blade shaft seat 10. One side of the saw blade shaft seat 10 facing the disc 6 is an inclined surface, and a driven ball 9 is installed on the inclined surface, forming an included angle with the axis of the saw blade shaft 11.

[0009] Preferably, both the driving ball 5 and the driven ball 9 are tangent to both side walls of the annular groove.

[0010] Preferably, the motor shaft 4 is fixed to the inner wall of the main body 1.

[0011] A design method of a medical gypsum saw, based on the medical oscillating saw, includes the step of designing the swing angle of the saw blade 12, specifically including: Step 1A: Mark two points on the adult skin and measure the distance L1 between the two points in the normal state; Then stretch the skin until pain is felt, and measure the distance L2 between the two points again; The preliminarily determined skin ductility C1 = L2 - L1; Step 1B: Considering the skin ductility of all populations, multiply the skin ductility obtained in Step 1A by a safety factor to obtain the final skin ductility C2 = a * C1; 0 < a < 1; Step 1C: According to the diameter and arc length calculation formula of the saw blade 12, calculate the central angle corresponding to the arc length of C2; the central angle is the rotation angle of the saw blade 12; Step 1D: The swing angle of the saw blade 12 is the rotation angle / 2.

[0012] Compared with the prior art, the advantages of the present invention are as follows: 1. The layout of the swing head assembly coaxially with the axis of the main body (motor) enables the coaxial deflection ball to drive the saw blade shaft to drive the saw blade to make high-frequency small-angle reciprocating movements around the axis of the saw blade. This does not block the field of view of the sawing operation and is more conducive to the operator observing the sawing situation.

[0013] 2. Since the deflection angle range of the saw blade 12 is [-3.5°, 3.5°], within this range, the skin always maintains ductility. Therefore, the skin will not be damaged during the process of cutting the plaster.

[0014] 3. The structure of this plaster saw has a coaxial layout and can be designed to be slender and short in shape, further reducing the overall weight. It is convenient for the palm to grip. The deflection ball and the disc belong to traditional regular shapes, making manufacturing easy, assembly simple, with low cost and easy to promote.

[0015] 4. The mechanical vibration of the structure transmission is small (the axis of the motor is coaxially arranged with the axis of the saw blade, and the active ball, the passive ball and the groove surface of the disc are tangent, always maintaining point contact), further enabling the sawing noise to be controllable ≤ 75 decibels at the highest rotational speed.

[0016] 5. Further reduce the external dimensions of the plaster saw (the axis of the motor is coaxially arranged with the axis of the saw blade, which can be compared with the parallel and spaced arrangement of the motor and the saw shaft of the pendulum saw on the existing market, with larger external dimensions).

[0017] 6. It has 1 - 6 gears for adjustable motor speed, which can be adjusted by the doctor (operator), beneficial to adjusting the noise of the plaster saw operation and the efficiency of sawing the plaster. Description of the Drawings

[0018] Figure 1 It is a cross-sectional view of a medical plaster saw; Figure 2 It is an external view of a medical plaster saw; Figure 3 It is a schematic installation view of the active ball on the motor shaft; Figure 4 It is a structural diagram of the motor shaft; Figure 5 It is a structural diagram of the saw blade shaft seat; Figure 6 It is a partial exploded view of a medical plaster saw; Figure 7 It is a structural diagram of the annular groove; Figure 8 It is a state diagram of the system after the saw blade swings 3.5°; Figure 9 It is a state diagram of the system after the saw blade swings -3.5°; Figure 10 It is a state diagram of the system when the saw blade is in the initial position; Figure 11 For obtaining the schematic diagram of the swing angle of the saw blade; Figure 12 For Figure 1 the partial view of; Figure 13 For the product drawing of the medical gypsum saw; Figure 14 For the test drawing of obtaining the swing angle of the saw blade.

[0019] Among them, 1 - main body, 2 - speed control knob, 3 - power switch; 4 - motor shaft, 5 - driving ball, 6 - disc, 7 - axial fixing piece, 8 - fixing pin, 9 - driven ball, 10 - saw blade shaft seat, 11 - saw blade shaft, 12 - saw blade, 13 - swing head assembly. Specific implementation manner

[0020] The medical gypsum saw of the present invention and its design method will be described in more detail below with reference to the schematic diagrams, in which the preferred embodiments of the present invention are shown. It should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as a broad guidance for those skilled in the art and not as a limitation to the present invention.

[0021] A medical gypsum saw is driven by an eccentric ball installed on the motor shaft to drive a disc with an annular groove, and the power is transmitted to another eccentric ball installed on one side of the disc through a certain angle setting, so as to drive the saw blade mounting shaft to perform the function of reciprocating radially around the saw blade axis to cut the gypsum. It is used to solve the problems of the large size of the existing gypsum saw structure (including the gypsum saw using eccentric fork transmission), especially the large eccentricity between the saw blade mounting shaft and the holding handle, resulting in the inconvenience of operation caused by the need to change the holding direction when cutting the gypsum and the harm caused by mis-cutting.

[0022] As Figures 1 to 14 , the medical gypsum saw includes: The swing head assembly 13, the positioning seat and the main body 1 are sequentially connected along the Y direction by fasteners; the main body 1 is the holding handle.

[0023] The saw blade 12 is arranged on the saw blade shaft 11 and is located outside the swing head assembly 13. The saw blade shaft 11 is rotatably installed in the swing head assembly 13. A section of the saw blade shaft 11 facing the main body 1, the saw blade shaft seat 10 and the driven ball 9 are sequentially connected; a preset distance along the X direction is formed between the driven ball 9 and the axis of the saw blade shaft 11 (that is, the driven ball 9 is eccentrically arranged); the driven ball 9 contacts the two side walls of the annular groove opened on the disc 6 and forms a rotation gap with the inner wall of the swing head assembly 13; The driven ball 9 is eccentrically arranged, forming a lever arm with the axis of the saw blade shaft 11, and the disc 6 transmits the driving torque to the saw blade shaft seat 10.

[0024] A disc 6 is used to drive a driven ball 9 to rotate around the axis of a saw blade shaft 11. It is sleeved on a fixed pin 8, and the fixed pin 8 is arranged on a swing head assembly 13 and extends along the X direction. There is a clearance fit between the disc 6 and the fixed pin 8. The driven ball 9 does not rotate around its own axis.

[0025] And a driving ball 5 is eccentrically arranged at the end of a motor shaft 4 and contacts both side walls of an annular groove formed on the disc 6. The motor shaft 4 is rotatably arranged in a positioning seat and extends along the Y direction into a main body 1. The motor corresponding to the motor shaft 4 is fixed in the main body 1. The driving ball 5 does not rotate around its own axis.

[0026] The axis of the main body 1, the axis of the motor shaft 4, the axis of a saw blade shaft seat 10, and the axis of the saw blade shaft 11 are coaxially arranged (coincide).

[0027] Furthermore, the end face of the motor shaft 4 where the driving ball 5 is installed is an inclined end face. The inclined end face and the driving ball installation hole are vertically arranged, which is conducive to the accurate positioning of the tool for machining the driving ball installation hole and is conducive to the axial limit of the driving ball after interference installation. The inclined surface and the driving ball limiting surface are parallel and coincident.

[0028] The inclined end face and the driving ball installation hole are vertically arranged, that is, the normal line of the inclined end face is parallel to the axis of the driving ball installation hole.

[0029] Preferably, the spherical surfaces of the driving ball 5 and the driven ball 9 are tangent to both side walls of the annular groove. The diameters of the driving ball 5 and the driven ball 9 are equal.

[0030] A section of the saw blade shaft 11 facing the main body 1, the saw blade shaft seat 10, and the driven ball 9 are connected in sequence. The specific connection method involved is as follows: The saw blade shaft 11 is clamped in the saw blade shaft seat 10. One side of the saw blade shaft seat 10 facing the disc 6 is an inclined surface, and the driven ball 9 is fixedly installed on the inclined surface, forming an angle with the axis of the saw blade shaft 11.

[0031] Regarding the swing head assembly 13: The swing head assembly 13 includes: A first installation channel and a second installation channel that extend along the Y direction and are connected. The first installation channel is used to install the saw blade shaft 11 and is open at one end facing the saw blade 12. The second installation channel is used to install the saw blade shaft seat 10, the driven ball 9, and the disc 6; And a pin hole that extends along the X direction and is used to install the fixed pin 8. The pin hole communicates with the second installation channel. Specifically, there is an interference fit between the fixed pin 8 and the pin hole.

[0032] Regarding the first installation channel: A first bearing cover, a first bearing, a transition cylinder, a second bearing, and a second bearing cover are sequentially arranged in the first installation channel; The first bearing cover is in interference fit with the swing head assembly 13, and the second bearing cover is placed on the step formed between the first installation channel and the second installation channel; one end of the saw blade shaft 11 is located outside the first bearing cover, and the other end sequentially passes through the first bearing, the transition cylinder, the second bearing, and the second bearing cover and extends towards the second installation channel.

[0033] As Figure 1 shown, the outer ring of the first bearing is clamped in the first installation channel and remains stationary.

[0034] The outer ring of the second bearing is clamped in the first installation channel and remains stationary.

[0035] The transition cylinder is clamped in the first installation channel.

[0036] Regarding the second installation channel: An axial fixing piece 7 is clamped between the second installation channel and the disc 6, and a fixing pin 8 passes through the axial fixing piece 7. Both of the pair of axial positioning pieces 7 are in contact with the disc 6; the side of the axial fixing piece 7 facing the disc 6 is a plane to be adapted to the disc 6.

[0037] Among them, "adapted" means that both the axial fixing piece 7 and the fixing pin 8 remain stationary. During the process of the disc 6 swinging around the fixing pin 8, the plane A on the disc 6 contacts the plane B on the axial fixing piece 7 and swings on the surface of the plane B.

[0038] Regarding the positioning seat: A third installation channel corresponding to the second installation channel and for installing the motor shaft 4 is provided in the positioning seat; A sealing ring is clamped on the inner wall of the third installation channel, and a third bearing is clamped in the sealing ring. The third bearing is placed on the shoulder of the motor shaft 4. The outer ring of the third bearing remains stationary.

[0039] In addition, a power switch 3 and a speed regulation knob 2 are provided on the main body 1.

[0040] The power switch 3, the power supply, and the motor form a closed loop.

[0041] Adjust the speed regulation knob 2 so that the motor has different speeds from 1 to 6 gears. Specifically, the speed regulation knob is a thin circle, and the circular ring surface is engraved with the numbers 1 to 6. The end faces of the circular rings corresponding to the numbers are provided with resistors and reed pieces of different lengths, which are connected to a specific speed controller.

[0042] Due to the lack of the function of adjusting the sawing speed of the existing gypsum saw, it cannot adapt to the replacement of saw blades with different diameters, resulting in inconsistent linear speeds of the rotating saw blades. Further, it affects the sawing efficiency of gypsum caused by inconsistent linear speeds at the same rotational speed. The cutting linear speed - for example, a saw blade with a smaller diameter requires a higher rotational speed to achieve a cutting effect with a higher linear speed, etc.

[0043] In this embodiment, the axis of the driving ball 5 and the axis of the motor shaft 4 form an included angle of 3.5° therebetween to achieve eccentric setting, and the driving ball 5 is in interference fit with the motor shaft 4.

[0044] The central hole of the disc 6 is penetrated by a cylindrical pin 8 and is fixedly wrapped in the central hole of the swing head assembly 13 by two disc angular fixing pieces 7.

[0045] The driven ball 9 has the same ball diameter as the driving ball 5 and is fixed on the 45-degree inclined plane of the saw blade shaft seat 10.

[0046] The saw blade shaft seat 10 has a square through groove axially and is in square coaxial interference fit with the saw blade shaft 11.

[0047] The end face at the uppermost end of the saw blade shaft 11 has a cross step for installing a circular or sector-shaped saw blade 12, and the saw blade 12 is fastened to the saw blade shaft 11 by an inner hexagon bolt and a pressure plate.

[0048] Press the power switch 3 to energize the motor placed in the main body 1. At this time, the motor shaft 1 drives the driving ball 5 to rotate, and the disc 6 is driven to swing reciprocally by ±3° around the fixed pin 8 (which can be imagined as the swing of a rattle). Among them, the rotation direction of the motor 1 remains unchanged. During one rotation of the motor, the disc 6 swings reciprocally, and the saw blade 12 swings reciprocally around the saw blade shaft 11.

[0049] From Figures 8 to 9 : The direction when the disc 6 swings into the paper surface is the positive direction. When the disc 6 swings by 3.5°, the saw blade 12 rotates counterclockwise.

[0050] Due to the reciprocal swing of the disc 6, it is transmitted to the driven ball 9 tangent to the annular groove in the annular groove of the disc 6. The driven ball 9 makes a small-angle reciprocal swing around the saw blade shaft 11, and synchronously transmits the reciprocal swing through the saw blade shaft seat 10 and the saw blade shaft 11 to the saw blade 12 to make a high-frequency reciprocal movement around the saw blade axis, realizing integral power transmission, and finally realizing the function of sawing gypsum.

[0051] Among them, the principle of converting the swing of the disc 6 into the rotational movement of the driven ball 9: The driven ball 9 is connected to the saw blade shaft seat 10 as a whole, and the saw blade shaft seat 10 has only the rotational freedom around the Y direction (the axis direction of the saw blade shaft). Therefore, when the disc 6 acts on the driven ball 9, the saw blade shaft seat 10 can only rotate around the Y direction.

[0052] The speed regulation knob 2 placed on the side of the main body 1 has 1 - 6 gears and can realize speed regulation from 8000 to 15000 revolutions per minute. It is more conducive to adjusting the rotation speed (sawing efficiency) for the actual operation of doctors.

[0053] Figure 12 For Figure 1Partial enlarged view, so in the two figures, there will be slight differences in the shapes of some components, such as the driving ball 5 and the driven ball 9.

[0054] Such as Figure 11 As shown, the included angle between the axis of the driven ball 9 and the axis of the saw blade shaft 11 in the saw blade fixing seat 10 is a fixed 45-degree angle, and the deflection angle of the driving ball 5 fixed to the end face of the motor shaft 4 is 3.5 degrees.

[0055] Such as Figure 14 As shown, the specific experimental steps are as follows: Step 1: Design the swing angle of the saw blade 12, that is, the deflection angle.

[0056] Step 1A: Mark two points on the adult skin and measure the distance L1 between the two points in the normal state.

[0057] After that, stretch the skin until pain is felt, and then measure the distance L2 between the two points again.

[0058] The initially determined skin ductility C1 = (L2 - L1).

[0059] Step 1B: Considering the skin ductility of all people, multiply the skin ductility obtained in Step 1A by a safety factor to obtain the final skin ductility C2 = a * C1; 0 < a < 1 Step 1C: According to the diameter and arc length calculation formula of the saw blade 12, calculate the central angle corresponding to the arc length of C2. The central angle is the rotation angle range of the saw blade 12.

[0060] The saw teeth within the central angle range are the saw teeth participating in the cutting movement.

[0061] Such as Figure 10 For the middle saw blade, the number of saw teeth participating in the sawing is 2.5 teeth, and on both sides of the central perpendicular line of the saw blade are plus and minus 3.5°. That is, the rotation angle range of the saw blade 12 is 7°.

[0062] Such as Figure 14 As shown, the skin ductility of an adult is 15 mm, and the calculated final skin ductility C2 is 4 mm.

[0063] Step 1D: The swing angle of the saw blade 12 is plus and minus 3.5° Step 2: According to the swing angle of the saw blade 12, find out the included angle between the axis of the driving ball 5 and the axis of the motor shaft 4, and the included angle between the axis of the driven ball 9 and the axis of the saw blade shaft 11.

[0064] When the eccentric angle of the driving ball 5 is plus or minus 3.5°, by designing the output inclined plane on the driving ball, the compound movement of the driving ball drives the swing angle of the swing plate to be plus or minus 3.5°. When the swing plate swings, it drives the driven ball to move. Due to the axial positioning reason of the driven ball, the circumferential speed of the driven ball (i.e., the circumferential rotation of the swing saw) needs to be faster than the vertical speed (axial speed), so that the circumferential direction can drive the part 11 to rotate in time. Otherwise, it will be jammed and unable to rotate. That is, the vertical speed is less than the tangential speed, which means the inclination angle is less than 45 degrees. If the angle is 0 degrees, that is, coaxial with the axis and the speed is 0, it cannot rotate. Therefore, after optimization, 45 degrees is the angle of the driven ball, so that the rotation speed of the driven ball is consistent with the swing direction and speed of the swing plate. Therefore, the included angle between the driven ball 9 and the saw blade axis is 45 degrees.

[0065] In addition, in the embodiment, through a large number of experiments, it is obtained that only when the included angle between the driving ball 5 and the axis of the motor shaft 4 is plus or minus 3.5° and the included angle between the driven ball 9 and the axis of the saw blade shaft is 45 degrees, can the swing angle of the saw blade 12 be guaranteed to be plus or minus 3.5°. The above is only the preferred embodiment of the present invention and does not impose any limitation on the present invention. Any person skilled in the art, without departing from the technical solution of the present invention, makes any form of equivalent substitution or modification and other changes to the technical solution and technical content disclosed in the present invention, which are all within the content of the technical solution of the present invention and still fall within the protection scope of the present invention.

Claims

1. A medical plaster saw, characterized in that: include: The swing head assembly (13), the positioning seat and the main body (1) are connected in sequence along the Y direction; A saw blade (12) is arranged on a saw blade shaft (11) and is located outside a swing head assembly (13); the saw blade shaft (11) is rotatably mounted inside the swing head assembly (13); a section of the saw blade shaft (11) facing the main body (1), a saw blade shaft seat (10) and a driven ball (9) are sequentially connected; a preset distance is formed along the X direction between the driven ball (9) and the axis of the saw blade shaft (11); the driven ball (9) contacts the two side walls of an annular groove formed on the disc (6), and forms a rotation gap with the inner wall of the swing head assembly (13); The circular disc (6) is used to drive the driven ball (9) to rotate around the axis of the saw blade shaft (11), and is sleeved on a fixing pin (8). The fixing pin (8) is arranged on the swing head assembly (13) and extends along the X direction; and an active ball (5), which is eccentrically arranged at the end of the motor shaft (4) and contacts the two side walls of the annular groove formed on the disc (6); the motor shaft (4) is rotatably arranged on the positioning seat and extends into the main body (1) along the Y direction; and a motor corresponding to the motor shaft (4) is arranged in the main body (1); The axis of the motor shaft (4) is coaxially arranged with the axis of the saw blade shaft (11).

2. The medical plaster saw according to claim 1, characterized in that: The swing head assembly (13) comprises: A first installation channel and a second installation channel extending in the Y direction and connected to each other; the first installation channel is used to install the saw blade shaft (11) and is open at one end toward the saw blade (12); the second installation channel is used to install the saw blade shaft seat (10), the driven ball (9) and the disc (6); and a pin hole extending along the X direction and used for installing a fixing pin (8), the fixing pin (8) being interference fit with the pin hole; the pin hole is connected to the second installation channel.

3. The medical plaster saw according to claim 2, characterized in that: The No. 1 installation channel is provided with a No. 1 bearing cap, a No. 1 bearing, a transition tube, a No. 2 bearing, and a No. 2 bearing cap in sequence; The No. 1 bearing cap is interference-fitted with the swing head assembly (13), and the No. 2 bearing cap is placed on a step, which is formed between the No. 1 installation channel and the No. 2 installation channel; one end of the saw blade shaft (11) is located outside the No. 1 bearing cap, and the other end passes through the No. 1 bearing, the transition cylinder, the No. 2 bearing, the No. 2 bearing cap in sequence, and extends toward the No. 2 installation channel.

4. The medical plaster saw according to claim 2, characterized in that: A third installation channel corresponding to the second installation channel and used for installing the motor shaft (4) is provided in the positioning seat; A sealing ring is mounted on the inner wall of the No. 3 installation channel, a No. 3 bearing is mounted in the sealing ring, and the No. 3 bearing is placed on a shaft shoulder on the motor shaft (4).

5. The medical plaster saw according to claim 2, characterized in that: An axial fixing sheet (7) is disposed between the second installation channel and the disc (6), the fixing pin (8) passes through the axial fixing sheet (7), a pair of axial positioning sheets (7) are both in contact with the disc (6), and a side of the axial fixing sheet (7) facing the disc (6) is flat so as to fit the disc (6).

6. The medical plaster saw according to claim 1, characterized in that: The saw blade shaft (11) is clamped in the saw blade shaft seat (10); the side of the saw blade shaft seat (10) facing the disc (6) is an inclined surface; a driven ball (9) is mounted on the inclined surface, and an angle is formed between the driven ball (9) and the axis of the saw blade shaft (11).

7. The medical plaster saw according to claim 1, characterized in that: The active ball (5) and the driven ball (9) are both tangent to the two side walls of the annular groove.

8. The medical plaster saw according to claim 1, characterized in that: The motor shaft (4) is fixed to the inner wall of the main body (1).

9. A method for designing a medical plaster saw, based on the medical plaster saw according to any one of claims 1 to 8, characterized in that: The method comprises the steps of designing the swing angle of the saw blade (12), specifically comprising: Step 1A, mark two points on the adult skin and measure the distance L1 between the two points under normal conditions; Then pull the skin until pain is felt, and measure the distance L2 between the two points again; The skin extensibility was initially determined to be C1 = L2- L1; Step 1B, considering the skin ductility of all people, multiply the skin ductility obtained in step 1A by a safety factor to obtain the final skin ductility C2=a*C1; 0<a<1; Step 1C, according to the diameter of the saw blade (12) and the arc length calculation formula, calculate the center angle corresponding to the arc length C2; the center angle is the rotation angle of the saw blade (12); Step 1D: The swing angle of the saw blade (12) is the rotation angle / 2.

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