Watertight watchcase
By satin-treated on the surface of the sealing area of the ceramic watertight case, concentric scratches are formed, which solves the problem of watertight sealing difficulty in high-hardness ceramic materials, and achieves the effect of maintaining watertightness at high depths.
Patent Information
- Application Number
- CN202411624351.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-11-15
- Filing Date
- 2024-11-14
- Publication Date
- 2025-05-16
AI Technical Summary
It is difficult to achieve effective watertight sealing under high-hardness ceramic materials. It is mainly due to the processing scratches at the sealing joints between the centerpiece and the bottom cover that cause air to enter, affecting watertightness.
By satining the surface of the sealing area between the centerpiece and the bottom cover, groups of concentric scratches are formed, which are contained within the perimeter of the surface, preventing air from entering and forming an air barrier when the joints deform, ensuring a watertight seal.
It is achieved to maintain watertightness under high hardness ceramic materials, especially at a depth of 600 meters, and the problem of watertight loss caused by processing scratches is avoided.
Smart Images
Figure CN120010217A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a watertight watch case made of ceramic material. Background Art
[0002] The watch case is usually made of ceramic material, which has the following advantages: it has high hardness, which ensures its ability to not be scratched. For example, the prior art discloses a watertight watch case made of ceramic material, and in particular, made of sintered zirconium oxide, which usually has a HV10 hardness of about 1200.
[0003] For watch cases that must remain watertight at depths of hundreds of meters, or even up to 600 meters, watertightness problems have been observed for ceramics such as silicon nitride with a hardness greater than 1600 HV10. Upon analysis, this loss of watertightness was attributed to the difficulty in achieving a clean machining result for this hardness on the bearing surfaces of the joints that seal the centerpiece and bottom cover of the case. Diamond wheels are usually used on CNC machines to machine these surfaces. These wheels machine the surface by rotating around themselves at high speed. This rotational motion leaves machining scratches on the entire machined surface. As Figure 1 As diagrammatically shown in FIG. 5 , these scratches 5 lead to the outside of the surfaces 2 a , 3 a and, during use, may form air inlet points which compromise the water-tightness of the shell. Summary of the invention
[0004] The object of the present invention is to overcome this drawback by modifying the shape of the scratches so that they no longer lead to the outside of the surface. The invention consists in producing, after machining, a satin finish effect on the surface forming the sealing zone between the centerpiece and the bottom cover, so as to obtain groups of concentric scratches. These grooves are contained within the perimeter of the surface, which prevents the entry of air. When the joint is deformed, it matches the shape of the grooves. The fact that the grooves are on the same axis as the joint creates an air barrier, thus guaranteeing a watertight seal. On the other hand, when the grooves extend transversely to the joint, the joint cannot be deformed sufficiently to fill all the grooves. This results in microchannels of air and makes the joint leak at great depths.
[0005] More specifically, the invention relates to a watertight case comprising a centerpiece, a bottom cover and a sealing joint arranged between the centerpiece and the bottom cover, the centerpiece and the bottom cover being made of a ceramic material having a hardness greater than or equal to 1600 HV10, the centerpiece comprising a lower face and the bottom cover comprising an upper face, the lower face and the upper face facing each other and acting as bearing surfaces for the sealing joint, the watertight case being characterized in that the lower face and the upper face are formed by sets of concentric scratches. According to the invention, the lower face and the upper face comprise only concentric scratches or consist of concentric scratches.
[0006] The best results are obtained if the lower and upper faces have a given roughness. Thus, the arithmetic mean of the roughness of the lower and upper faces, called roughness Ra, is between 0.1 and 0.8 μm in a direction perpendicular to the tangent at the point of the concentric scratch, the roughness Ra being measured in said direction over the entire width of the lower and upper faces according to standards ISO 4287, ASME B46.1-2019.
[0007] Furthermore, the maximum roughness, referred to as roughness Rt, measured according to standards ISO 4287, ASME B46.1-2019, is between 1 and 5 μm over the entire width of the lower face and the upper face in the same direction.
[0008] The invention also relates to a method for finishing (finition in French) said watertight case, comprising the step of satin-finishing the lower face and the upper face so as to obtain said set of concentric scratches. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 The sealing zone of a watch case according to the prior art is diagrammatically shown, which, after machining, has scratches leading to the outside of this zone.
[0010] Figure 2 The same sealing area is shown after satin finishing according to the invention.
[0011] Figure 3a and Figure 3b Under an optical microscope, Figure 1 and Figure 2 Observations of the diagram shown in the figure.
[0012] Figure 4a and Figure 4b Shows the direction in which the roughness measurement is made.
[0013] Figure 5 is a partial cross-sectional view of a watch case according to the present invention. DETAILED DESCRIPTION
[0014] The invention relates to a watertight watch case made of a ceramic material having a hardness greater than or equal to 1600 HV10, or even greater than or equal to 1800 HV10. HV10 hardness is understood to mean the Vickers hardness measured according to standard ISO 6507-1:2018. Preferably, the ceramic material is silicon nitride (Si3N4). According to the invention, the watch case is capable of remaining watertight at a depth of 600 metres, irrespective of the system used to assemble the bottom cover to the centrepiece, whether by screw connection or otherwise.
[0015] exist Figure 5The case 1 shown in a partial cross-sectional view in FIG. 1 comprises in a known manner a centerpiece 2 and a bottom cover 3, wherein a sealing joint 4 is provided between the centerpiece and the bottom cover and is intended to be compressed between a bearing surface 2a (also called lower face) of the centerpiece 2 and a bearing surface 3a (also called upper face) of the bottom cover 3. In the example shown, the case is circular and the joint is an O-ring. According to the invention, the case can be of any shape (square, rectangular, etc.) and the joint can be of any shape or material.
[0016] The centerpiece 2 comprises a lower face 2a and the bottom cover 3 comprises an upper face 3a, the two faces 2a, 3a facing each other and acting as bearing surfaces for the joint 4, as described above. Preferably, these bearing surfaces are flat. According to the invention, the lower face 2a and the upper face 3a have scratches 5 which do not lead to the outer perimeter of the faces. This prevents air or liquids from penetrating into the shell. More specifically, in Figure 2 The scratches 5 visible in the figure form groups of concentric scratches around the central axis of the case. These scratches are shaped similarly to the faces and the joint. Thus, if the latter is circular, the scratches are circular and concentric. If the faces are substantially rectangular, the scratches will be substantially rectangular and concentric, and so on.
[0017] According to the invention, the surface treatment is determined by the shape of the scratches and by the roughness of the surface including the scratches. To achieve the best results, the arithmetic mean roughness Ra measured according to the standard ISO 4287, ASME B46.1-2019 is as follows: Figure 4a The roughness Rt in the direction perpendicular to the tangent line at the point of the concentric scratch shown in is between 0.1 and 0.8 μm over the entire width L of the lower and upper faces. In the same direction, the maximum roughness Rt measured according to the same standard is between 1 and 5 μm.
[0018] Advantageously, in another direction perpendicular to the above direction, along half of the width L of the surface, such as Figure 4b As shown in , the arithmetic mean roughness Ra is between 0.1 and 0.7 μm and the maximum roughness Rt is between 1 and 4 μm when measured from and towards the outer periphery of the face.
[0019] According to the invention, the scratches are produced by satin finishing. Preferably, the satin finishing is performed using a diamond strip or a grinding wheel. Another technique consists in using a laser to produce the satin finishing effect. The satin finishing is performed after machining the lower and upper faces of the centerpiece and bottom cover, respectively. The scratches may have a variable width and are typically less than one micrometer in width.
[0020] Figure 3a shows the surface of one of the two faces after machining without the satin finishing step according to the invention; Figure 3bThe same surface after the satin finishing step is shown. These results are shown in Figure 1 and Figure 2 middle.
[0021] Regardless of the system used to assemble centerpiece and bottom-cap, optimal watertightness at a depth of 600 metres is ensured thanks to concentric grooves in the sealing area between centerpiece and bottom-cap.
Claims
1. A watertight watch case (1), comprising a center piece (2), a bottom cover (3) and a sealing joint (4) arranged between the center piece (2) and the bottom cover (3), the center piece (2) and the bottom cover (3) being made of a ceramic material having a hardness greater than or equal to 1600 HV10, the center piece (2) comprising a lower face (2a) and the bottom cover (3) comprising an upper face (3a), the lower face (2a) and the upper face (3a) facing each other and acting as bearing surfaces for the sealing joint (4), the watertight watch case (1) being characterized in that the lower face (2a) and the upper face (3a) are formed by a group of concentric scratches (5).
2. The watertight watch case (1) according to claim 1, characterized in that: The arithmetic mean of the roughness, called roughness Ra, of the lower face (2a) and the upper face (3a) is between 0.1 and 0.8 μm in a direction perpendicular to the tangent at the point of the concentric scratch (5), and the roughness Ra is measured over the entire width (L) of the lower face (2a) and the upper face (3a) in said direction according to standards ISO 4287, ASME B46.1-2019.
3. The watertight watch case (1) according to claim 2, characterized in that: Over the entire width (L) of the lower face (2a) and the upper face (3a) in said direction, the maximum roughness, referred to as roughness Rt, measured according to standards ISO 4287, ASME B46.1-2019, is between 1 and 5 μm.
4. The watertight watch case (1) according to claim 2 or 3, characterized in that: Completely across said lower face (2a) and said upper face (3a), along half of their width (L), in a direction perpendicular to said direction, the roughness Ra is between 0.1 and 0.7 μm, and the roughness Rt is between 1 and 4 μm.
5. Watertight watch case (1) according to any one of the preceding claims, characterized in that The hardness is greater than or equal to 1800 HV10.
6. Watertight watch case (1) according to any one of the preceding claims, characterized in that The ceramic material is silicon nitride.
7. Watertight watch case (1) according to any one of the preceding claims, characterized in that The lower face (2a) and the upper face (3a) are flat.
8. Watertight watch case (1) according to any one of the preceding claims, characterized in that It is capable of remaining watertight at depths of up to 600 meters.
9. A method for finishing a watertight watch case (1) according to any one of the preceding claims, characterized in that The method comprises the step of satin-finishing the lower face (2a) and the upper face (3a) to obtain the set of concentric scratches (5).
10. Method for finishing the watertight watch case (1) according to the preceding claim, characterized in that The satin finishing step is performed using a diamond stick or grinding wheel.