Quick-response plug-in PT100 temperature sensor and manufacturing process thereof

Abstract

The embodiment of the invention discloses a quick-response plug-in PT100 temperature sensor and a manufacturing process thereof.The temperature sensor comprises a resistor assembly and a shell assembly, the resistor assembly comprises a coil and a micro ceramic tube, the outer diameter of the micro ceramic tube is 0.9 mm, the coil is formed by winding a pure platinum wire with the diameter of 0.02 mm, the resistance value of the coil at the normal temperature is 109.73 ohm, and the resistance value of the shell assembly is 109.73 ohm. The coil is embedded or inserted into an inner cavity of the micro ceramic tube, the resistance is adjusted by pressing pins and an ice-water mixture, and glaze sealing is performed after the resistance value at zero degree is stabilized at 100 ohms; the shell assembly comprises a needle tube type stainless steel shell, the outer diameter of the stainless steel shell is 1.3 mm, the resistor assembly is installed in the stainless steel shell, before installation, the outer wall of the micro ceramic tube is coated with heat-conducting glue, and after installation, a gap between the inner wall of the stainless steel shell and the outer wall of the micro ceramic tube is filled with the heat-conducting glue. The system has the advantages of miniaturization, high response speed, accurate capture of temperature change, stable performance, good durability, localization, low application cost and the like.

Description

Technical Field

[0001] This invention relates to the field of temperature sensor technology, specifically to a fast-response insertion-type PT100 temperature sensor and its manufacturing process. Background Technology

[0002] In the field of industrial measurement and control, Pt100 temperature sensors are widely used in various temperature measurement scenarios due to their high accuracy, good stability, and wide applicability. With the increasing demands for automation and precision control, higher requirements are being placed on the miniaturization and rapid response capabilities of temperature sensors. Especially in space-constrained applications or where rapid temperature change capture is required, such as medical equipment, semiconductor manufacturing, and microreactors, traditional fast-response insertion-type Pt100 sensors are typically limited by processing technology and structural design (usually made by winding platinum wire onto a ceramic, glass, or mica skeleton and then undergoing complex processing). Their probe outer diameter can only reach a minimum of about Φ2mm, making further miniaturization difficult. Currently, most mainstream high-performance fast-response Pt100 sensors on the market rely on imported products. Although they possess excellent response speeds (up to 0.74 seconds), their sizes are still concentrated at Φ2mm and above, and their costs are high with long delivery cycles. Domestic products of the same type have long faced technical bottlenecks in response speed and miniaturization (temperature sensing elements are usually encapsulated in a protective shell. However, this encapsulation method may increase thermal inertia, resulting in a longer response time, thereby affecting the sensor's fast response performance), making it difficult to meet the needs of high-end application scenarios. Summary of the Invention

[0003] Therefore, embodiments of the present invention provide a fast-response insertion-type PT100 temperature sensor and its manufacturing process to solve one or more of the above-mentioned technical problems.

[0004] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0005] The first aspect of this invention provides a fast-response insertion-type PT100 temperature sensor, comprising:

[0006] A resistor assembly comprising a coil and a micro-ceramic tube, the outer diameter of the micro-ceramic tube being 0.9 mm, the coil being made of pure platinum wire with a diameter of 0.02 mm, the coil having a resistance of 109.73 Ω at room temperature, the coil being embedded or inserted into the inner cavity of the micro-ceramic tube, the resistance being adjusted by pressing the pins and using an ice-water mixture, and the resistance being stabilized at 100 Ω at zero degrees before glazing.

[0007] The housing assembly includes a needle-shaped stainless steel housing with an outer diameter of 1.3 mm. The resistor assembly is installed inside the stainless steel housing. Before installation, thermally conductive adhesive is applied to the outer wall of the micro-ceramic tube. After installation, the gap between the inner wall of the stainless steel housing and the outer wall of the micro-ceramic tube is filled with the thermally conductive adhesive.

[0008] Furthermore, the length of the micro-ceramic tube is 10 mm, and the length of the stainless steel shell is 26 mm.

[0009] Furthermore, the outer casing assembly also includes a rear casing, the front end of which is provided with an insertion hole for the stainless steel casing to be inserted into. The rear end of the stainless steel casing is inserted into the inner cavity of the rear casing through the insertion hole and fixed with glue. After the glue dries and the product performance is measured to meet the requirements, glue is filled into the rear casing.

[0010] Furthermore, the rear housing includes an insertion part at the front end, a limiting part in the middle section, and a potting part at the rear end. The insertion hole is located at the axis of the insertion part, and the potting part is provided with a strip-shaped potting groove. The lead wire connected to the pin of the resistor assembly extends out from the potting groove.

[0011] Furthermore, the outer diameter of the limiting part is 10mm and the length is 6mm; the outer diameter of the glue-filling part is 8mm and the length is 12mm; the length of the glue-filling groove is 12mm and the width is 3.5mm.

[0012] Furthermore, the housing assembly also includes a flange, which has a plurality of bolt holes evenly distributed on a virtual circle with a diameter of 29.7 mm centered on the axis of the flange; the rear side of the flange has a forward-extending but not through insertion hole, into which the insertion part is inserted and fixed with adhesive; the front side of the flange has a through hole communicating with the insertion hole.

[0013] Furthermore, the flange has an outer diameter of 34mm and a thickness of 5mm; there are 4 through bolt holes with an inner diameter of 5mm; the insertion part has an outer diameter of 2.3mm and a length of 3mm; the insertion hole has an inner diameter of 2.3mm and a depth of 3mm; and the through hole has an inner diameter of 1.3mm.

[0014] Furthermore, a circular boss is provided on the front side of the flange, the circular boss is coaxial with the flange, and the through hole passes through the front side of the circular boss.

[0015] Furthermore, the front side of the circular boss is a sealing surface, and the outer diameter of the circular boss is 16.3-16.5mm, and the thickness is 1.8-2mm.

[0016] The second aspect of this invention provides a manufacturing process for a fast-response insertion-type PT100 temperature sensor, used to manufacture the fast-response insertion-type PT100 temperature sensor provided in the first aspect of this invention, comprising the following steps:

[0017] A pure platinum wire with a diameter of 0.02 mm was wound into a coil with a resistance of 109.73 Ω at room temperature. The coil was then placed inside a micro ceramic tube. The resistance was measured with a high-precision multi-function digital multimeter and adjusted by pressing the pins and using an ice-water mixture (0°C) to make the resistance value 100 Ω. After the resistance value was stabilized through multiple tests, the tube was fixed, glazed, and made into a resistor assembly.

[0018] Solder and fix the pins and leads at the tail end of the resistor assembly, and ensure insulation; apply thermally conductive adhesive to the outer periphery of the micro ceramic tube, and insert the resistor assembly into the inner cavity of the stainless steel housing;

[0019] Insert the rear end of the stainless steel housing into the insertion hole at the front end of the rear housing, with the lead wire extending out of the glue-filling groove. Fix the stainless steel housing and the rear housing with glue. After the glue dries, measure the product's technical performance. If it meets the requirements, fill the glue-filling groove at the rear of the rear housing with glue to ensure the product's sealing performance.

[0020] After the adhesive dries, the front end of the rear housing is inserted into the rear side of the flange and bonded in place. The stainless steel housing extends out from the front end of the flange. Once the adhesive dries, the product manufacturing is complete.

[0021] The embodiments of the present invention have the following advantages:

[0022] I. Extreme miniaturization, breaking through space application limitations

[0023] The probe uses a 0.9mm micro-ceramic tube to encapsulate a platinum wire coil and is paired with a 1.3mm needle-shaped stainless steel housing. The probe's outer diameter is reduced by more than 35% compared to traditional products (2mm and above), making it suitable for space-constrained scenarios such as medical equipment and micro-reaction devices.

[0024] The overall structure is compact, and the rear housing and flange are ingeniously designed (the flange outer diameter is only 34mm), which takes up little space during installation and is compatible with the integration requirements of high-end precision equipment.

[0025] II. Improve response speed and accurately capture temperature changes

[0026] The resistor assembly adopts a thin-walled micro ceramic tube and thermally conductive adhesive filling design. The thermally conductive adhesive fills the gap between the ceramic tube and the stainless steel shell to reduce heat transfer resistance. Combined with the structure of direct temperature sensing by the platinum wire coil, thermal inertia is significantly reduced.

[0027] With a non-redundant packaging structure and a short temperature conduction path between the platinum wire coil and the external environment, the response speed can be further optimized compared to traditional sensors with protective shells, meeting the needs of rapid temperature measurement scenarios such as semiconductor manufacturing.

[0028] III. Stable performance and good durability

[0029] The coil is glazed, and the outer casing is sealed with multiple adhesives and potting compounds, providing both insulation and resistance to environmental interference. The flange sealing surface design further enhances the sealing performance, making it suitable for use in complex working conditions.

[0030] The pure platinum wire, combined with a ceramic tube and stainless steel shell, is resistant to high temperatures and corrosion, extending the product's service life and ensuring long-term measurement stability.

[0031] IV. Achieve localization and reduce application costs

[0032] Breaking the technological monopoly of imported high-end PT100 sensors, we have achieved miniaturization and rapid response performance through independently developed manufacturing processes, with core parameters comparable to or even superior to imported products.

[0033] Compared to imported products, it significantly shortens the supply cycle and reduces production costs. At the same time, the structural design can be flexibly adjusted according to demand, enhancing the autonomy and cost-effectiveness of domestic high-end equipment components.

[0034] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of this application will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0035] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0036] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0037] Figure 1 A schematic diagram of the structure of a fast-response insertion-type PT100 temperature sensor provided in an embodiment of the present invention;

[0038] Figure 2 for Figure 1 A magnified view of A in the middle.

[0039] In the diagram: 1. Coil; 2. Micro ceramic tube; 3. Stainless steel housing; 4. Rear housing; 41. Insertion part; 42. Limiting part; 43. Glue filling part; 44. Glue filling tank; 5. Flange; 51. Through bolt hole; 52. Circular boss. Detailed Implementation

[0040] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] like Figure 1 and 2 As shown, this embodiment provides a fast-response insertion-type PT100 temperature sensor, including a resistor assembly and a housing assembly. The resistor assembly includes a coil 1 and a micro-ceramic tube 2. The outer diameter of the micro-ceramic tube 2 is 0.9 mm. The coil 1 is made of pure platinum wire with a diameter of 0.02 mm. The resistance of the coil 1 at room temperature is 109.73 Ω. The coil 1 is embedded or inserted into the inner cavity of the micro-ceramic tube 2. The resistance is adjusted by pressing the pins and using an ice-water mixture. After the resistance is stabilized at 100 Ω at zero degrees Celsius, it is glazed. The housing assembly includes a needle-shaped stainless steel housing 3 with an outer diameter of 1.3 mm. The resistor assembly is installed inside the stainless steel housing 3. Before installation, thermally conductive adhesive is applied to the outer wall of the micro-ceramic tube 2. After installation, the gap between the inner wall of the stainless steel housing 3 and the outer wall of the micro-ceramic tube 2 is filled with thermally conductive adhesive. Pins and leads are omitted in the figure.

[0042] The probe employs a 0.9mm micro-ceramic tube 2 paired with a 0.02mm pure platinum wire coil 1, significantly reducing the core size compared to traditional products, overcoming miniaturization bottlenecks and adapting to space-constrained scenarios. Thermally conductive adhesive fills the gap between the ceramic tube and the 1.3mm stainless steel housing 3, reducing heat transfer resistance, lowering thermal inertia, and significantly improving response speed. The "pressed pin + 0℃ ice water resistance adjustment" process ensures a precise and stable resistance of 100Ω at 0℃, while glaze sealing enhances insulation and structural stability, guaranteeing temperature measurement accuracy.

[0043] In an optional or preferred embodiment, the length of the micro-ceramic tube 2 is 10 mm, and the length of the stainless steel shell 3 is 26 mm.

[0044] The 10mm long micro-ceramic tube 2 and the 26mm long stainless steel shell 3 are matched in size, which ensures the installation space and temperature sensing range of the coil 1, while further optimizing the overall miniaturization and taking into account both temperature sensing efficiency and structural compactness.

[0045] In an optional or preferred embodiment, the housing assembly further includes a rear housing 4. The front end of the rear housing 4 is provided with an insertion hole for inserting a stainless steel housing 3. The rear end of the stainless steel housing 3 is inserted into the inner cavity of the rear housing 4 through the insertion hole and fixed with glue. After the glue dries and the product performance is measured to meet the requirements, glue is filled into the rear housing 4.

[0046] The rear housing 4 is glued and fixed to the stainless steel housing 3, and then sealed with glue afterward. This not only ensures stable assembly of the components but also improves the product's waterproof and anti-interference capabilities, preventing external environmental factors from affecting the internal circuit performance and extending its service life. Testing performance before applying glue after it dries allows for early detection of defective products, reducing subsequent rework costs and ensuring product consistency.

[0047] In an optional or preferred embodiment, the rear housing 4 includes an insertion part 41 at the front end, a limiting part 42 in the middle section, and a potting part 43 at the rear end. The insertion hole is located at the axis of the insertion part 41, and the potting part 43 is provided with a strip-shaped potting groove 44. The lead wire connected to the pin of the resistor assembly extends out from the potting groove 44.

[0048] The rear housing has a 4-segment design (insertion part 41, limiting part 42, and potting part 43), which clearly defines the function of each part. The insertion part 41 ensures precise docking with the stainless steel housing 3, the limiting part 42 facilitates assembly and positioning, and the potting groove 44 facilitates the extension of the lead wire and provides a channel for potting, thus improving the ease of assembly.

[0049] In an optional or preferred embodiment, the outer diameter of the limiting part 42 is 10 mm and the length is 6 mm; the outer diameter of the glue-filling part 43 is 8 mm and the length is 12 mm; and the length of the glue-filling groove 44 is 12 mm and the width is 3.5 mm.

[0050] The specific dimensions of the limiting part 42, the glue-filling part 43 and the glue-filling tank 44 are designed to balance structural strength and operating space, ensuring the stability of the rear shell 4 while facilitating glue-filling construction and lead wire layout, thereby improving production efficiency.

[0051] In an optional or preferred embodiment, the housing assembly further includes a flange 5, which has a plurality of bolt holes 51 evenly distributed on a virtual circle with a diameter of 29.7 mm centered on the axis of the flange 5; the rear side of the flange 5 has a forward-extending but not through insertion hole, into which the insertion part 41 is inserted and fixed with adhesive; the front side of the flange 5 has a through hole communicating with the insertion hole.

[0052] The flange 5 is quickly fixed and installed through four evenly distributed through bolt holes 51, which meets the standardized assembly requirements of industrial equipment; the insertion part 41 is precisely inserted and fixed with the insertion hole to ensure the overall coaxiality of the sensor and avoid assembly deviations from affecting the accuracy of temperature measurement.

[0053] In an optional or preferred embodiment, the flange 5 has an outer diameter of 34 mm and a thickness of 5 mm; it has four through bolt holes with an inner diameter of 5 mm; the insertion part 41 has an outer diameter of 2.3 mm and a length of 3 mm; the insertion hole has an inner diameter of 2.3 mm and a depth of 3 mm; and the through hole has an inner diameter of 1.3 mm.

[0054] The precise dimensional design of flange 5 and other parts ensures both installation stability and compatibility, while controlling the overall volume. It also ensures a tight fit between the stainless steel housing 3 and the through holes, reducing heat transfer loss and guaranteeing response speed.

[0055] In an optional or preferred embodiment, a circular boss 52 is provided on the front side of the flange 5. The circular boss 52 is coaxial with the flange 5, and a through hole is provided on the front side of the circular boss 52.

[0056] The design of the circular boss 52 concentrates the through holes in the boss area, which facilitates the precise docking of the sensor and the device under test. At the same time, the boss structure enhances the structural strength of the front end of the flange 5 and avoids damage to the sealing surface during assembly.

[0057] In an optional or preferred embodiment, the front side of the circular boss 52 is a sealing surface, and the outer diameter of the circular boss 52 is 16.3-16.5 mm and the thickness is 1.8-2 mm.

[0058] The design of the circular boss 52 and the sealing surface improves the sealing performance of the sensor and the equipment mounting surface, preventing the intrusion of impurities such as dust and moisture, adapting to complex industrial conditions, and ensuring long-term stable operation.

[0059] This embodiment also provides a manufacturing process for a fast-response insertion-type PT100 temperature sensor, which is used in the fast-response insertion-type PT100 temperature sensor provided in the above embodiment, and includes the following steps:

[0060] Step S1: Fabrication of the resistor assembly. A pure platinum wire with a diameter of 0.02mm is wound into a coil 1 with a resistance of 109.73Ω at room temperature. This coil 1 is then placed inside a micro-ceramic tube 2. A high-precision digital multimeter is used to measure the resistance, and the resistance is adjusted by pressing the pins and applying an ice-water mixture (0℃) to achieve a value of 100Ω. After multiple tests to ensure the resistance remains stable, the tube is fixed and glazed to complete the resistor assembly. In this step, products that do not meet the requirements (e.g., the resistance at the freezing point after adjustment is not 100Ω, or the resistance value is unstable after multiple tests) are discarded.

[0061] Step S2: Assemble the component made in step S1 with the stainless steel housing 3. Solder and fix the pins and leads at the tail end of the resistor component and ensure insulation; apply thermally conductive adhesive to the outer periphery of the micro ceramic tube 2 and insert the resistor component into the inner cavity of the stainless steel housing 3.

[0062] Step S3: Assemble the components made in step S2 with the rear housing 4. During assembly, insert the rear end of the stainless steel housing 3 into the insertion hole at the front end of the rear housing 4, with the lead wire extending from the glue-filling groove 44. Secure the stainless steel housing 3 and the rear housing 4 with adhesive. After the adhesive dries, measure the product's technical performance. If it meets the requirements, fill the glue-filling groove 44 at the rear of the rear housing 4 with adhesive to ensure the product's sealing performance.

[0063] Step S4: Assemble the components made in step S3 with the flange 5. After the glue dries, insert the front end of the rear housing 4 into the rear side of the flange 5 and fix it in place. The stainless steel housing 3 extends out from the front end of the flange 5. After the glue dries, the product manufacturing is complete.

[0064] It should be noted that parts such as coil 1, micro ceramic tube 2, stainless steel shell 3, rear shell 4, and flange 5 were all pre-processed.

[0065] The process steps are clear and orderly, from the precise fabrication of resistor components (wire winding, resistance adjustment, and glazing) to the overall assembly (welding, potting, and fixing). Each step takes into account both precision and stability, ensuring product consistency and reliability. The inclusion of key steps (multiple tests after resistance adjustment and performance testing before potting) effectively avoids production defects and improves yield. At the same time, the standardized process facilitates large-scale production, helps achieve domestic substitution, and reduces costs and delivery cycles.

[0066] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A fast responding plug-in PT100 temperature sensor characterized in that, It comprises: a resistance assembly, which comprises a coil and a micro ceramic tube, the outer diameter of the micro ceramic tube is 0.9 mm, the coil is made of pure platinum wire with a diameter of 0.02 mm, the resistance value of the coil at normal temperature is 109.73 Ω, the coil is embedded or inserted into the inner cavity of the micro ceramic tube, and the resistance value at zero degree is stabilized at 100 Ω by pressing the pin, ice water mixture resistance adjustment and glaze sealing; a shell assembly, which comprises a needle tube type stainless steel shell, the outer diameter of the stainless steel shell is 1.3 mm, the resistance assembly is installed in the stainless steel shell, before installation, heat-conducting glue is applied to the outer wall of the micro ceramic tube, and after installation, the gap between the inner wall of the stainless steel shell and the outer wall of the micro ceramic tube is filled with the heat-conducting glue.

2. The fast response, plug-in PT100 temperature sensor of claim 1, wherein, The length of the micro ceramic tube is 10 mm, and the length of the stainless steel shell is 26 mm.

3. The fast response, plug-in PT100 temperature sensor of claim 1, wherein, The shell assembly further comprises a rear shell, the front end of the rear shell is provided with an insertion hole for inserting the stainless steel shell, the rear end of the stainless steel shell is inserted into the inner cavity of the rear shell through the insertion hole and is fixed with glue, after the glue is dry, the product performance is measured and meets the requirements, and then the rear shell is filled with glue.

4. The fast response, plug-in PT100 temperature sensor of claim 3, wherein, The rear shell comprises an insertion part at the front end, a limiting part at the middle section and a glue filling part at the rear section, the insertion hole is arranged at the axis of the insertion part, and the glue filling part is provided with a strip-shaped glue filling groove, and the lead wire connected with the pin of the resistance assembly is stretched out of the glue filling groove.

5. A fast responding, plug-in PT100 temperature sensor as claimed in claim 4, characterized in that, The outer diameter of the limiting part is 10 mm, and the length is 6 mm; the outer diameter of the glue filling part is 8 mm, and the length is 12 mm; the length of the glue filling groove is 12 mm, and the width is 3.5 mm.

6. The fast response, insertion PT100 temperature sensor of claim 4, wherein, The shell assembly further comprises a flange, the flange is provided with a plurality of bolt holes, the plurality of bolt holes are uniformly distributed on a virtual circle with a diameter of 29.7 mm and with the axis of the flange as the center; the rear side of the flange is provided with an insertion hole extending forward but not penetrating through, the insertion part is inserted into the insertion hole and fixed with glue; the front side of the flange is provided with a through hole communicating with the insertion hole.

7. A fast responding plug-in PT100 temperature sensor as claimed in claim 6, characterized in that, The outer diameter of the flange is 34 mm, and the thickness is 5 mm; the bolt hole is provided with four, and the inner diameter is 5 mm; the outer diameter of the insertion part is 2.3 mm, and the length is 3 mm; the inner diameter of the insertion hole is 2.3 mm, and the depth is 3 mm; the inner diameter of the through hole is 1.3 mm.

8. The fast response, insertion PT100 temperature sensor of claim 6, wherein, The front side of the flange is provided with a circular boss, the circular boss is coaxial with the flange, and the through hole penetrates through the front side of the circular boss.

9. The fast response, insertion PT100 temperature sensor of claim 8, wherein, The front side of the circular boss is a sealing surface, the outer diameter of the circular boss is 16.3-16.5 mm, and the thickness is 1.8-2 mm.

10. A process for the production of a fast responding plug-in PT100 temperature sensor according to any one of claims 1 to 9, characterized in that, It comprises the following steps: A pure platinum wire with a diameter of 0.02 mm is wound into a coil with a resistance value of 109.73 Ω at normal temperature, the coil is installed in a micro ceramic tube, a high-precision digital multimeter is used for measurement, the pin is pressed, ice water mixture resistance adjustment is performed, the resistance value is 100 Ω, multiple tests are performed to stabilize the resistance value, and then the resistance assembly is fixed, glazed and made. The pin at the tail end of the resistance assembly is welded with the lead wire and fixed with insulation; the outer periphery of the micro ceramic tube is coated with heat conductive glue, and the resistance assembly is inserted into the inner cavity of the stainless steel shell; The rear end of the stainless steel shell is inserted into the insertion hole at the front end of the rear shell, the lead wire is extended out of the glue pouring groove, and the stainless steel shell and the rear shell are fixed with glue; after the glue is dry, the technical performance of the product is measured, and after meeting the requirements, the glue is poured through the glue pouring groove at the rear of the rear shell to ensure the sealing performance of the product; After the glue is dry, the front end of the rear shell is inserted into the rear side of the flange plate and is fixed by adhesion, and the stainless steel shell is extended out of the front end of the flange plate, and the product is completed after the glue is dry.

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