Dental handpiece and root canal preparation machine

Abstract

The dental handpiece comprises a handle, a handpiece shell and a machine core assembly, the machine core assembly comprises a shaft core and a needle clamping elastic piece used for clamping a work tip, the needle clamping elastic piece comprises a closed section and an open-loop section which are coaxially connected, and a plurality of cutting grooves penetrating in the radial direction are formed in the open-loop section; the inclined or arc-shaped cutting grooves are adopted to separate the elastic limiting pieces on the clamping needle elastic piece, so that the effects of clamping a work tip and ensuring concentricity are achieved, stress of the gradual change areas of the elastic limiting pieces is dispersed, the service life of the elastic limiting pieces is prolonged, the service life of the clamping needle elastic piece and even a dental handpiece is prolonged, the structural change is small, and the structure is simple and convenient to implement. And the process and the cost are slightly changed, and popularization and application are facilitated. The invention also discloses a root canal preparation machine comprising the dental handpiece.

Description

Technical Field

[0001] The invention relates to the technical field of oral medical instruments, and in particular to a dental mobile phone and a root canal preparation machine. Background Art

[0002] Dental handpieces are mainly used in tooth treatment, restoration and oral surgery, and can be used as components of root canal preparation machines. This type of equipment realizes its function through the use of working tips such as clamped burs or root canal files, and the working tips need to be disassembled and replaced according to different needs.

[0003] A dental handpiece generally includes a handpiece and a handle. The handpiece is arranged at one end of the handle. A movement assembly is arranged inside the handpiece. The working tip is detachably mounted on the movement assembly. In order to facilitate the disassembly and replacement of various working tips and realize the coaxial installation of the working tip, a common method is to use the needle clamping spring in the movement assembly to clamp and fix the working tip. For example, Chinese patent CN216221718U-Dental handpiece and its handpiece discloses that the shaft core is sleeved outside the needle clamping spring, the root canal file is inserted into the needle clamping spring, and the needle clamping spring is used to clamp the turning needle. The three are arranged coaxially. The needle clamping spring includes a closed section and an open loop section. The open loop section has four slots (i.e., straight slots) extending along the preset axis direction, which divide the open loop section into two elastic limiting sheets with limiting protrusions and toggling parts and two positioning sheets. The needle clamping spring plays two roles. The first role is to clamp and lock the root canal file, which is achieved by the elastic limiting sheet. The second role is to ensure that the shaft core, the needle clamping spring, and the root canal file are coaxially arranged. The concentricity of the three is mainly achieved by the closed section, while the positioning piece can play a positioning role and then play an auxiliary concentricity role. The elastic limiting piece and the positioning piece are separated on the open ring section by opening a straight groove. It is very convenient in processing, and it also has great advantages in yield rate and consumables. It can clamp and lock the root canal file and ensure concentricity. Therefore, for the prior art, the technical personnel in this field have an inertial thinking at the current stage: the elastic limiting piece and the positioning piece are separated by a straight groove, which has become the needle clamping spring design form commonly used by technical personnel in this field.

[0004] However, each time the root canal file is replaced, the two elastic limiting pieces of the needle clamping shrapnel will undergo a relatively large elastic deformation. As the equipment is used for a longer time, the number of elastic deformations of the elastic limiting pieces will continue to accumulate and increase. Since the conventional design adopts the method of opening straight grooves, the width of the elastic limiting piece remains unchanged, so that when the elastic limiting piece is deformed, the stress is concentrated at the root of the elastic limiting piece. There is also a scheme of step-by-step thickening at the root of the elastic limiting piece (such as Chinese patent CN215349603U), but the stress will also be concentrated in the place where the thickness changes. The stress concentration will make the elastic limiting piece prone to fatigue fracture, thereby reducing the service life of the needle clamping shrapnel. In addition, when using a dental mobile phone, the head needs to be inserted into the oral cavity with the working tip, so the head needs to be made relatively small and precise, and the parts inside the head cannot be replaced. When the needle clamping shrapnel is damaged, the entire dental mobile phone will not be able to continue to be used. Therefore, the service life of the needle clamping shrapnel becomes the main factor limiting the service life of the dental mobile phone. Summary of the invention

[0005] In order to overcome at least one of the above-mentioned defects of the prior art, the present invention provides a dental handpiece, which can increase its service life and has little change in process and cost compared with the prior art.

[0006] The technical solution adopted by the present invention to solve the problem is:

[0007] A dental handpiece includes a handle, a head shell, and a core assembly. The head shell is arranged at one end of the handle, a pressing piece is arranged on the head shell, and the core assembly is rotatably arranged in the head shell. The core assembly includes an axis core and a needle clamping spring piece for clamping a working tip. The axis core is sleeved outside the needle clamping spring piece. The needle clamping spring piece is tubular and includes a closed section and an open ring section that are coaxially connected.

[0008] The open loop section is provided with a plurality of radially penetrating grooves, and the plurality of grooves separate the open loop section into at least one elastic limiting piece. The elastic limiting piece is provided with a limiting protrusion for cooperating with the groove of the working tip and a toggle portion for cooperating with the pressing piece. The elastic limiting piece has a gradient zone, a first end of the gradient zone is close to the closed section, and a second end of the gradient zone extends in a direction away from the closed section. At least a portion of an edge on one side of the groove extends in an inclined or arc shape on the circumferential surface of the open loop section, so that the circumferential width of the gradient zone gradually increases from the second end to the first end.

[0009] Optionally, a plurality of cut grooves separate the open loop segment into at least one positioning piece.

[0010] Optionally, the radial thickness dimension of the gradient zone gradually increases from the second end to the first end.

[0011] Optionally, the inner side surface of the gradual change zone is parallel to the axis of the needle clamping spring piece, and the outer side surface of the gradual change zone is inclined or has an arc-shaped transition.

[0012] Optionally, both side edges of the groove extend in an inclined shape or an arc shape.

[0013] Optionally, the circumferential width dimension of the first end of the gradient zone is a, the circumferential width dimension of the second end of the gradient zone is b, and the coefficient k=a / b, where 1 <k≤1.7。

[0014] Optionally, k=1.5.

[0015] Optionally, the length dimension of the gradual change zone along the axial direction is h, wherein h≥a.

[0016] Optionally, h≥1.5a.

[0017] Optionally, a rounded transition is further provided at the connection between the first end of the gradient zone and the closed section.

[0018] Optionally, the elastic limiting plate also has a constant width zone, which is connected to the second end of the gradient zone, the circumferential width of the constant width zone is consistent with the circumferential width of the second end of the gradient zone, and the limiting protrusion and the toggle portion are arranged on the constant width zone.

[0019] Based on the same inventive concept, the present invention also discloses a root canal preparation machine, including the above-mentioned dental handpiece.

[0020] The dental handpiece provided by the present invention has the following technical effects:

[0021] The elastic limiting piece is separated from the needle clamping spring piece by an inclined or arc-shaped groove to meet the function of clamping the working tip and ensuring concentricity, and to disperse the stress of the gradual change area of ​​the elastic limiting piece, thereby increasing the service life of the elastic limiting piece, thereby increasing the service life of the needle clamping spring piece and even the dental handpiece, and its structural change is small, so that the change in process and cost is very small, which is conducive to popularization and use. Other beneficial effects will be shown in the specific implementation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the partial cross-sectional structure of a dental mobile phone according to an embodiment of the present invention.

[0023] Figure 2 This is a structural schematic diagram of a needle clamping spring in an embodiment of the present invention, in which the gradient zone is set to a first length.

[0024] Figure 3 for Figure 2 The cross-sectional structural diagram of the needle clamping spring is shown.

[0025] Figure 4This is a schematic structural diagram of a needle clamping spring in an embodiment of the present invention, in which the gradient zone is set to a second length.

[0026] Figure 5 This is a schematic structural diagram of a needle clamping spring in an embodiment of the present invention, in which the gradient zone is set to a third length.

[0027] Figure 6 This is a structural schematic diagram of a needle clamping spring in an embodiment of the present invention, in which the gradient zone is set to a fourth length.

[0028] Figure 7 It is a schematic diagram of stress analysis when the coefficient k=1 in the prior art.

[0029] Figure 8 It is a schematic diagram of stress analysis when the coefficient k=1.5 of an embodiment of the present invention.

[0030] Fig. 9 It is a schematic diagram of stress analysis when the coefficient k=2 according to an embodiment of the present invention.

[0031] Fig.10 The experimental data record chart of the pressing life of the clamping needle spring under different k values.

[0032] The meanings of the reference numerals are as follows:

[0033] 1. Handle; 2. Machine head housing; 21. Pressing piece; 3. Axis core; 4. Needle clamping spring; 41. Closed section; 42. Open loop section; 43. Cutting groove; 44. Elastic limiting piece; 441. Limiting protrusion; 442. Toggle part; 443. Gradient zone; 444. Constant width zone; 45. Positioning piece; 5. Working tip; 51. Groove. DETAILED DESCRIPTION

[0034] For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0035] In the description of the present invention, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0036] In addition, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it 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, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0038] Throughout the development process of dental mobile phones, the installation methods of the working tips on the mobile phone heads have gradually developed into rotary installation, push-type installation, and button-type installation. In the button-type installation scheme, the needle clamping spring in the movement assembly is generally used to clamp and fix the working tip. Specifically, the needle clamping spring is installed in the shaft core, and the working tip is inserted into the needle clamping spring. When the shaft core rotates, the needle clamping spring rotates with the working tip. It is divided into low-speed mobile phones and high-speed mobile phones. The speed of low-speed mobile phones is usually below 30,000 revolutions per minute, and the speed of high-speed mobile phones is usually as high as 350,000 to 400,000 revolutions per minute (RPM), or even higher. The requirements for concentricity and clamping force are relatively high. Therefore, in addition to mainly using the closed section in the needle clamping spring to achieve concentricity, a clamping locking mechanism is also provided in the needle clamping spring. An elastic limiting piece is used as the tip, and a positioning piece is set to assist in concentricity. The positioning piece is used to counter-position with the structure on the inner side of the shaft core, so as to facilitate the installation and coordination of other structures, and also to assist in improving the concentricity. It can also provide a certain clamping pre-tightening force for the working tip. Combined with the clamping and locking effect of the elastic limiting piece, it meets the requirements of high speed, large clamping force, high stability and other requirements of the dental mobile phone. Since the volume of the needle clamping spring piece is relatively small, in the existing production process of the needle clamping spring piece, a straight groove is opened along the axial direction at one end of the needle clamping spring piece to separate the elastic limiting piece and the positioning piece, so that the elastic limiting piece and the positioning piece are processed as a whole on the needle clamping spring piece. The requirements for the grooving equipment are relatively low, and it is very convenient in processing. At the same time, it also has great advantages in yield rate and consumables. Therefore, opening a straight groove has become the inertial thinking of technical personnel in this field.

[0039] With the development of the market, the frequency of using dental handpieces in hospitals or dental clinics has skyrocketed, and the number of times the working tips need to be replaced has increased significantly. As time goes by, the service life of the needle clamp shrapnel has an increasingly greater impact on the overall impact of the dental handpiece, and has gradually become the main factor restricting the service life of the dental handpiece.

[0040] Based on the above reasons, the present invention provides a dental handpiece, which overcomes the technical prejudice of those skilled in the art that a straight groove is used to separate the elastic limiting piece 44 on the needle clamping spring piece 4, and instead uses an inclined or arc-shaped groove 43 to separate the elastic limiting piece 44, and on the basis of meeting the basic functional requirements of the needle clamping spring piece 4, overcomes the defect of excessive stress concentration of the elastic limiting piece 44 during elastic deformation, which is also the main technical feature and innovation of the present invention. The present invention also provides a root canal preparation machine, which includes the dental handpiece of the present invention.

[0041] like Figures 1 to 3 As shown, the dental mobile phone of the present invention includes a handle 1, a head shell 2, and a movement assembly. The head shell 2 is arranged at one end of the handle 1, and the movement assembly is rotatably arranged in the head shell 2. The movement assembly includes an axis core 3 and a needle clamping spring piece 4. The axis core 3 is driven by a power mechanism (not exhibited). The power mechanism can be a known electric or pneumatic mechanism (because it is not the innovative point of the present invention, it is not limited or elaborated). The axis core 3 is sleeved on the outside of the needle clamping spring piece 4. The needle clamping spring piece 4 is tubular and is used to clamp the working tip 5. When the axis core 3 rotates, the needle clamping spring piece 4 and the working tip 5 rotate together, and the axes of the axis core 3, the needle clamping spring piece 4 and the working tip 5 coincide.

[0042] The needle clamp spring piece 4 includes a closed section 41 and an open ring section 42 that are coaxially connected. The open ring section 42 is provided with four radially penetrating grooves 43. The grooves 43 extend in an arc shape on the circumferential surface of the open ring section 42. The four grooves 43 divide the open ring section 42 into two elastic limiting pieces 44 and two positioning pieces 45. The two elastic limiting pieces 44 are arranged opposite to each other, and the two positioning pieces 45 are arranged opposite to each other. One of the longer positioning pieces 45 is used to abut against the structure (such as a convex ring) on ​​the inner side of the shaft core 3 for positioning, and the other shorter positioning piece 45 does not need to abut against the shaft core 3, so as to improve the positioning accuracy and simplify the production process. A limiting protrusion 441 and a toggle portion 442 are provided on the elastic limiting piece 44. The limiting protrusion 441 is used to cooperate with the groove 51 of the working tip 5 to clamp and lock the working tip 5. The head housing 2 is provided with The pressing piece 21 and the toggle portion 442 are used to cooperate with the pressing piece 21 so that when the pressing piece 21 is operated, the toggle portion 442 can drive the elastic limiting piece 44 to expand so as to pull out or insert the working tip 5. The elastic limiting piece 44 has a gradient zone 443 and a constant width zone 444. The first end of the gradient zone 443 is close to the closed section 41. Preferably, the first end of the gradient zone 443 is connected to the closed section 41, and the second end of the gradient zone 443 extends in a direction away from the closed section 41. The constant width zone 444 is connected to the second end of the gradient zone 443. The circumferential width of the constant width zone 444 is consistent with the circumferential width of the second end of the gradient zone 443. The limiting protrusion 441 and the toggle portion 442 are arranged on the constant width zone 444. Based on the arc-shaped cutting groove 43, the circumferential width dimension of the gradient zone 443 gradually increases from its second end to the first end.

[0043] Specifically, Figure 2 With reference to the direction shown, the two grooves 43 located on the left and right sides of the elastic limiting piece 44 both extend outward in an arc shape, so that the gradient zone 443 of the elastic limiting piece 44 is symmetrically narrow at the top and wide at the bottom.

[0044] Optionally, a rounded transition is further provided at the connection between the first end of the gradual change zone 443 and the closed section 41 to further disperse the stress.

[0045] Optionally, the radial thickness of the gradient zone 443 is kept consistent to avoid stress concentration caused by uneven wall thickness of the gradient zone 443 .

[0046] It should be noted that the groove 43 may only have one side extending in an arc shape, specifically, the side shared by the groove 43 and the elastic limiting plate 44 extending in an arc shape; and the other side of the groove 43 (that is, the side shared by the groove 43 and the positioning plate 45) may be an arc-shaped extension, or an inclined extension or an axial extension, etc., and no limitation is made on the other side of the groove 43 herein. Of course, it is preferred that the other side of the groove 43 also extends in an arc shape to facilitate the processing of the groove 43.

[0047] In another optional embodiment, the groove 43 may extend in an inclined shape on the circumferential surface of the open ring section 42, and the circumferential width of the gradual change zone 443 may also gradually increase from the second end to the first end. Similarly, the groove 43 may extend in an inclined shape on only one side (the side shared by the groove 43 and the elastic limiting sheet 44), while the other side (i.e., the side shared by the groove 43 and the positioning sheet 45) may not be limited.

[0048] It should be noted that the number of slots 43, the number of elastic limiting pieces 44, and the number of positioning pieces 45 can be adjusted and changed according to design requirements, and their specific numbers are not limited. For example, there can be two slots 43, and one elastic limiting piece 44 and one positioning piece 45; or, there can be three slots 43, one elastic limiting piece 44, and two positioning pieces 45; or, there can be four slots 43, one elastic limiting piece 44, and three positioning pieces 45. When there is only one elastic limiting piece 44 and two or more positioning pieces 45, only the two slots 43 on the two opposite sides of the elastic limiting piece 44 can extend in an arc shape or extend in an arc shape.

[0049] Through the above scheme, in the dental mobile phone of the present invention, an inclined or arc-shaped groove 43 is used to separate an elastic limiting piece 44 on the needle clamping spring piece 4 to meet the functions of clamping the working tip 5 and ensuring concentricity, and the circumferential width dimension of the gradient zone 443 of the elastic limiting piece 44 is gradually increased from its second end to the first end, thereby reducing the stress concentration of the elastic limiting piece 44 during bending deformation, dispersing the bending stress of the elastic limiting piece 44, and improving the service life of the elastic limiting piece 44, thereby improving the service life of the needle clamping spring piece 4 and even the dental mobile phone, and its structural change is small, only the shape of the groove 43 and the corresponding cutting process are changed, so that the changes in process and cost are very small, which is conducive to promotion and use, and has great use value.

[0050] It should be noted that the gradient zone 443 and the constant width zone 444 are not limited to different areas that produce actual structural divisions, but are only virtual area divisions. The gradient zone 443 and the constant width zone 444 can be identified based on the starting position where the circumferential width of the elastic limiting piece 44 changes, thereby starting from the starting position (the starting position should be located on the side of the limiting protrusion 441 facing the closed section 41), the gradient zone 443 is close to the closed section 41, and the constant width zone 444 is far from the closed section 41.

[0051] In this embodiment, based on the relative relationship between the length of the gradient zone 443 along the axial direction and the length of the positioning piece 45 along the axial direction, the gradient zone 443 and the constant width zone 444 can be divided into the following types:

[0052] (I) Reference Figure 2 And Figure 2Directions shown are for reference only, length dimensions are shown as Figure 2 As shown in the height dimension, the two positioning pieces 45 are one taller and one shorter, and the cutting groove 43 extends in an entire arc shape, with the axis of the arc located on the horizontal extension line of the upper surface of the positioning piece 45 on the left. At this time, the length of the gradient zone 443 is equal to the length of the positioning piece 45 on the left, and the dividing line between the gradient zone 443 and the constant width zone 444 is flush with the upper surface of the positioning piece 45 on the left.

[0053] (II) Reference Figure 4 And Figure 4 Directions shown are for reference only, length dimensions are shown as Figure 4 As shown in the height dimension, the two positioning pieces 45 are one tall and one short, the shape of the groove 43 on the left is straight on the top and arc on the bottom, and the groove 43 on the right extends in an entire arc shape, and the axis of the arc is located on the horizontal extension line of the upper surface of the positioning piece 45 on the right. At this time, the length of the gradient zone 443 is equal to the length of the positioning piece 45 on the right, and the dividing line between the gradient zone 443 and the constant width zone 444 is flush with the upper surface of the positioning piece 45 on the right.

[0054] (III) Reference Figure 5 by Figure 5 Directions shown are for reference only, length dimensions are shown as Figure 4 As shown in the height dimension, the two positioning pieces 45 are one tall and one short, and the shapes of the grooves 43 on the left and right sides are both straight on the top and arc on the bottom, and the axis of the arc is located below the upper surface of the positioning piece 45 on the right. At this time, the length of the gradient zone 443 is smaller than the length of the positioning piece 45 on the right, and the dividing line between the gradient zone 443 and the constant width zone 444 is located below the upper surface of the positioning piece 45 on the right.

[0055] (IV) Reference Figure 6 by Figure 6 Directions shown are for reference only, length dimensions are shown as Figure 6 As shown in the height dimension, the two positioning pieces 45 are one tall and one short, and the cutting groove 43 extends in an entire arc shape, with the axis of the arc located above the upper surface of the positioning piece 45 on the left. At this time, the length of the gradient zone 443 is greater than the length of the positioning piece 45 on the left, and the dividing line between the gradient zone 443 and the constant width zone 444 is located above the upper surface of the positioning piece 45 on the left, and can even be flush with the lower edge of the limiting protrusion 441.

[0056] The significance of distinguishing the constant width zone 444 from the gradient zone 443 is that the constant width zone 444 can retain the width dimension of the elastic limiting plate 44 in the prior art. When the product is updated, there is no need to change other components of the dental mobile phone, and only the needle clamping spring 4 can be replaced, thereby achieving the purpose of saving R&D, production and other costs.

[0057] It should be noted that in other examples, the lengths of different positioning pieces 45 can also be equal.

[0058] Refer to Figure 2 or Figure 4 or Figure 5 or Figure 6 , define the circumferential width dimension of the first end of the tapered region 443 as a, define the circumferential width dimension of the second end of the tapered region 443 as b, and define the axial length dimension of the tapered region 443 as h. Among them, let the coefficient k = a / b. This coefficient reflects the degree of the bottom transition of the elastic limiting piece 44. Combining Figure 8 and Fig.10 , 1 < k ≤ 1.7. Preferably, the value of k is between 1.3 and 1.7 (i.e., 1.3 ≤ k ≤ 1.7). More preferably, the value of k is 1.5. Stress dispersion at the bottom of the elastic limiting piece 44 can be achieved, and the width at the stress concentration point in the elastic limiting piece 44 can be increased (the stress concentration is at Figure 8 the darkest position in the grayscale. It can be seen that the stress concentration has been improved. The maximum stress point is still at the bottom of the elastic limiting piece 44. However, due to stress dispersion, when performing stress simulation analysis, the maximum stress value has dropped to 2.686e+009 (N / m2)), and through experiments, its average pressing life (times) is relatively high, so as to improve the fatigue life of the elastic limiting piece 44, and further improve the service life of the needle clamping elastic piece 4 and even the dental handpiece.

[0059] The size of the width transition change at the bottom of the elastic limiting piece 44 will also affect its fatigue life. If the change of a relative to b is too small, for example, when the value of k is 1 or close to 1, refer to Figure 7 and Fig.10 , the transition effect is not obvious, and the stress dispersion effect cannot be achieved. It is still easy to have stress concentration and fracture at the bottom of the elastic limiting piece 44 (the stress concentration is at Figure 7 the darkest position in the grayscale. It can be clearly seen that the stress concentration is at the bottom of the elastic limiting piece 44. When performing stress simulation analysis, the maximum stress value reaches 3.401e+009 (N / m2)), and through experiments, its average pressing life (times) is relatively low. If the change of a relative to b is too large, for example, when the value of k is 2 or close to 2, refer to Fig. 9 , the bottom of the elastic limiting piece 44 is too wide, and it is difficult for its bottom to deform, resulting in the upward shift of the stress concentration area (the stress concentration is at Fig. 9 the darkest position in the grayscale. It can be clearly seen that the stress is dispersed in the entire tapered region 443, but the stress concentration points are significantly increased and shifted upward). This will shorten the bendable length and increase the bending angle of the bent part. Since the width of the second end of the tapered region 443 is small, it is more likely to have fatigue fracture.

[0060] From the above, it can be known that through stress simulation analysis and control experiments, the present invention improves and innovates the needle clamping spring 4. When k takes a value of 1.5, the fatigue life of the needle clamping spring 4 is the highest, which is 1.97 times that of the prior art (i.e., k=1), and the average life is increased by nearly one-fold, which greatly improves the service life of the needle clamping spring 4 and even the dental mobile phone.

[0061] In addition, the axial length h of the gradient zone 443 will also affect the stress dispersion effect. If h is too small, it is difficult to achieve the stress dispersion effect. In this embodiment, preferably h≥a, more preferably h≥1.5a.

[0062] It should be noted that the results of the above stress simulation analysis and control experiments are only used to illustrate and explain the technical solution of the present invention, and are not intended to limit the magnitude of the stress and the magnitude of the pressing life.

[0063] In summary, the dental mobile phone provided by the present invention uses an inclined or arc-shaped groove 43 to separate the elastic limiting piece 44 on the needle clamping spring piece 4, so that the two sides of the bottom of the elastic limiting piece 44 have an inclined or arc-shaped transition, which reduces the stress concentration of the elastic limiting piece 44 when it is bent and deformed, and disperses the bending stress of the elastic limiting piece 44, thereby increasing the service life of the elastic limiting piece 44, thereby increasing the service life of the needle clamping spring piece 4 and even the dental mobile phone, and its structure changes little, only changing the shape of the groove 43 and the corresponding cutting process, so that the changes in process and cost are small. The change is very small, which is conducive to promotion and use, and has great use value; and by controlling the size of the ratio coefficient k between the circumferential width dimension a of the first end of the gradient zone 443 and the circumferential width dimension b of the second end, the relative size of the axial length dimension h of the gradient zone 443 and the circumferential width dimension a of the first end of the gradient zone 443 is controlled to further improve the service life of the elastic limiting plate 44; and by adding a rounded transition to further disperse the stress, and controlling the radial thickness dimension of the gradient zone 443 to remain consistent, the stress concentration caused by the uneven wall thickness of the gradient zone 443 is avoided.

[0064] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above-mentioned technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. A dental handpiece, characterized in that: It includes a handle, a head shell, and a core assembly. The head shell is arranged at one end of the handle. A pressing piece is arranged on the head shell. The core assembly is rotatably arranged in the head shell. The core assembly includes an axis core and a needle clamping spring for clamping the working tip. The axis core is sleeved outside the needle clamping spring. The needle clamping spring is tubular. The needle clamping spring includes a closed section and an open ring section that are coaxially connected. The open-loop segment is provided with a plurality of radially penetrating grooves, and the plurality of grooves separate the open-loop segment into at least one elastic limiting piece, and the elastic limiting piece is provided with a limiting protrusion for cooperating with the groove of the working tip and a toggle portion for cooperating with the pressing member, and the elastic limiting piece has a gradient zone, a first end of the gradient zone is close to the closed segment, and a second end of the gradient zone extends in a direction away from the closed segment, and at least a portion of an edge of one side of the groove extends in an inclined shape or an arc shape on the circumferential surface of the open-loop segment, so that the circumferential width dimension of the gradient zone gradually increases from its second end to the first end.

2. The dental handpiece according to claim 1, characterized in that: The plurality of cutting grooves further separate the open loop section into at least one positioning piece.

3. The dental handpiece according to claim 1, characterized in that: The radial thickness of the gradient zone gradually increases from the second end to the first end.

4. The dental handpiece according to claim 3, characterized in that: The inner side surface of the gradual change zone is parallel to the axis of the needle clamping spring piece, and the outer side surface of the gradual change zone is inclined or arc-shaped.

5. The dental handpiece according to claim 1, characterized in that: Both side edges of the cutting groove extend in an inclined shape or an arc shape.

6. The dental handpiece according to claim 1, characterized in that: The circumferential width dimension of the first end of the gradient zone is a, the circumferential width dimension of the second end of the gradient zone is b, and the coefficient k=a / b, where 1 <k≤1.7。 7. The dental handpiece according to claim 6, characterized in that: k＝1.5。 8. The needle clamping spring of the dental handpiece according to claim 6, characterized in that: The length dimension of the gradual change zone along the axial direction is h, wherein h≥a.

9. The dental handpiece according to claim 8, characterized in that: h≥1.5a.

10. The dental handpiece according to any one of claims 1 to 9, characterized in that: A rounded transition is also provided at the connection between the first end of the gradient zone and the closed section.

11. The dental handpiece according to any one of claims 1 to 9, characterized in that: The elastic limiting plate also has a constant width zone, which is connected to the second end of the gradient zone. The circumferential width of the constant width zone is consistent with the circumferential width of the second end of the gradient zone. The limiting protrusion and the toggle portion are arranged on the constant width zone.

12. A root canal preparation machine, characterized in that: Comprising a dental handpiece as claimed in any one of claims 1 to 11.

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