Smooth surface machining method for plastic molds

Abstract

This invention provides two methods for machining a smooth surface in a plastic mold. The first method is performed sequentially: step a) providing a mold blank with a rough textured area to be machined; and step c) using either magnetic or vibration grinding methods to refine the rough textured surface of the area to be machined into a smooth surface with a smooth texture. The second method adds a step b) polishing the rough textured surface of the area to be machined, roughing it to a fine textured surface. Step b is added between steps a and c, so that step c) is changed to: refining the fine textured surface of the area to be machined into a smooth surface with a smooth texture, which also enables the plastic mold to be machined to a smooth surface that meets the requirements.

Description

Technical Field

[0001] This invention relates to the field of vacuum forming, and more particularly to a method for processing a smooth surface of a mold to help the finished plastic product smoothly detach from the mold. Prior Technology

[0002] Typically, a mold receives thermoplastic material, which adheres to the inner surface of the mold due to vacuum. After a period of time, a finished product with the design outline of the mold is formed. The more contact surface between the finished product and the mold, the greater the friction, which hinders the demolding of the finished product.

[0003] In terms of mold making, aluminum mold blanks are generally selected, and the required molds are produced using computer numerical control (CNC) cutting, sand casting, or other methods. According to the design concept, the inner side of the mold conforms to the dimensional specifications. However, the mold has a rough textured surface, which increases the contact area between the mold and the finished product, making demolding difficult.

[0004] Therefore, how to process the surface of the mold blank and solve the problem of difficult demolding of plastic products has become a problem that the inventors of this case urgently need to overcome. Summary of the Invention

[0005] In view of this, the inventor of this case provides two processing methods. The main purpose of the first processing method is to smooth the rough texture of the mold blank to achieve a mirror-like surface, reduce the area of ​​the finished plastic product in contact with the mold, and overcome the drawback of difficulty in demolding.

[0006] To achieve the above objectives, the first processing method of the present invention is performed in sequence as follows: step a): providing a mold blank with a rough textured area to be processed; and step c): using one of two grinding methods, magnetic force or vibration, to refine the rough textured surface of the area to be processed into a smooth surface with smooth texture.

[0007] The main purpose of the second processing method is to refine the rough texture of the mold blank through rough processing and then smooth it through fine processing to achieve a near-mirror finish, thereby reducing the area of ​​the plastic finished product in contact with the mold and overcoming the drawback of difficulty in demolding.

[0008] To achieve the above objectives, the second processing method of the present invention is performed in sequence as follows: Step a): providing a mold blank with a rough textured area to be processed; Step b): polishing the rough textured surface of the area to be processed to a fine textured surface; and Step c): using one of two grinding methods, magnetic force or vibration, to finish the fine textured surface of the area to be processed into a smooth surface with smooth texture.

[0009] From a data perspective, step a) involves processing the area to be processed with rough textures of 3 mm or more; step b) involves processing the rough textures to fine textures of 3 mm to 0.1 mm; and step c) involves processing the fine textures to smooth textures, resulting in an average surface roughness (Ra) between 0.2 µm and 0.025 µm.

[0010] In some embodiments of this invention, the average surface roughness of the smooth texture 34 is between 0.1µm and 0.025µm.

[0011] To make the objectives, features and advantages of the present invention readily apparent, one or more preferred embodiments are described in detail below with reference to the accompanying drawings. Simple Explanation of the Diagram

[0012] Figure 1 illustrates the process of the first processing method for making a smooth surface of a plastic mold according to the present invention. Figure 2 illustrates the process of the second processing method for producing a smooth surface of a plastic mold according to the present invention. Figures 3-7 are photographs or diagrams comparing the production processes of the first and second processing methods. Implementation

[0013] Next, embodiments of this case will be described with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same or similar structures or units. It is foreseeable that the described embodiments are only some examples of this case, and not all embodiments. Other embodiments derived from the described examples, or structures modified or varied as needed, are all within the scope of protection of this case.

[0014] In the following description, directional terms such as "up," "down," "left," "right," "front," "back," "inside," "outside," and "side" are used only for reference to the directions in the accompanying drawings. The use of directional terms is for the purpose of better and clearer description and understanding of this application, and does not imply that the described device or element must have a specific orientation, structure, or operation, and therefore should not be construed as a limitation on the technical content of this application.

[0015] Unless specifically and explicitly stated otherwise, in the following description, "installed," "connected," "attached," or "on" should be interpreted broadly, including, for example, fixed connection, detachable connection, integral connection, mechanical connection, direct connection, indirect connection, or connection between two components. Those skilled in the art will understand the meaning of these terms in various embodiments, and even in the specific context, based on ordinary knowledge or experience.

[0016] Unless otherwise stated, in the following description, "multiple" means two or more.

[0017] Figure 1 illustrates the first method of the present invention, from step a, "preparing the mold blank 10", to step c, "smoothing the surface 14", which can refine the mold blank into a mold with a smooth surface. After vacuum forming, the smooth surface helps the plastic product to be easily demolded and removed.

[0018] In step a, the mold blank is usually made of aluminum and is produced by sand casting, computer numerical control (CNC) cutting or other methods.

[0019] The sand casting mentioned here can be a mixture of silica sand and water glass. A rough sand shell mold is made in a mold made of wood, wood substitute, bakelite, plaster, plastic or other materials. The mold is then immersed in molten metal at about 1000°C. After the metal cools down, the sand shell mold is removed to obtain a metal mold blank.

[0020] The CNC cutting mentioned here refers to the use of computer numerical control lathes, planers, milling machines and / or other mechanical equipment to cut a whole piece of raw material such as aluminum, copper, bakelite, wood substitute or other materials into a suitable contour according to the size specifications, and to form a complete mold blank.

[0021] The other methods mentioned here can be wire electrical discharge machining, grinding, or special machining methods. These other methods are used less frequently than the aforementioned sand casting and computer numerical control (CNC) cutting.

[0022] Figure 3 shows a photograph of the produced aluminum mold blank. In this embodiment, a recess of the mold blank 20 is considered as the processing area 21. A bottom surface 22 of the processing area 21 is recessed into the mold blank 20 to a certain depth, and the bottom surface 22 has some rough texture 30. The four sides 23 of the processing area 21 stand around the bottom surface 22, and the sides 23 also have rough texture 30.

[0023] Based on the above summary, step a prepares or provides the mold blank 20, which has a processing area 21 with rough texture 30.

[0024] Next, see Figure 1. Step c smooths out the rough texture, making the mold blank a near-smooth surface through finishing.

[0025] The finishing process referred to here generally refers to one of the two methods, magnetic grinding or vibratory grinding, to smooth the surface texture of the area to be processed.

[0026] The magnetic abrasive polishing mentioned here uses a magnetic field to drive stainless steel needles to quickly polish the surface of the area to be processed (or the mold blank), as well as to perform in-depth processing of small details to achieve a fine finish. After the treatment, the area to be processed will not deform and will not affect the size and specifications of the mold blank. Therefore, magnetic abrasive polishing is also known as Teflon-free surface treatment.

[0027] The vibratory grinding mentioned here uses the rotation of a motor in conjunction with the elasticity of a spring to generate high-frequency vibrations, and through the use of grinding stones and abrasives, a fine finishing effect is achieved.

[0028] Figure 6 shows a photograph of the mold blank 20 after grinding, and Figure 7 shows a cross-sectional view of the ground mold blank 20. As shown in Figures 6 and 7, step c uses either magnetic or vibration grinding to refine the rough textured bottom surface 22 of the area to be processed 21 into a smooth surface 26 with smooth textures 34. Similarly, the rough textured side surface 23 of the area to be processed 21 is also refined into a smooth surface 27 with smooth textures 34.

[0029] By examining the data, specifically the photographs or diagrams in Figures 3, 6, and 7, and comparing them with the first processing method in Figure 1, the differences between the smoothing process before and after creating the plastic mold according to this invention can be understood more intuitively:

[0030] First, the mold blank 20 provided in step a has a processing area 21, which usually has rough textures 30 that are clearly visible to the naked eye, about 3mm or more.

[0031] Then, in step c, the smooth surfaces 26 and 27 of the area to be processed 21 are finished using either magnetic or vibration grinding methods to obtain an average surface roughness (Ra) of 0.2µm to 0.025µm for the smooth texture 34. In some embodiments, the average surface roughness (Ra) of the smooth texture 34 is between 0.1µm and 0.025µm, and the mold blank 20 feels smooth to the touch.

[0032] Figure 2 illustrates the second method of the present invention, with an additional step b, "mold surface processing 12". Step b uses a surface processing method to roughen the original texture of the mold blank into a refined surface. Thus, by adding step b between steps a and c, the mold blank can also be processed into a mold with a smooth surface.

[0033] The surface treatment methods mentioned here refer to polishing, which usually involves using grinding machinery or equipment, taking different grades of sandpaper, and rotating at high speed to rub the original texture, refining the roughness and changing it into a texture with a lower height or shallower depth.

[0034] Figure 4 shows a photograph after polishing, and Figure 5 is a cross-sectional view of the mold blank 20 after polishing. It is easy to see from Figures 4 and 5 that the rough texture of step a is transformed into a fine texture 32 after polishing, resulting in a fine surface 24 on the bottom of the area to be processed 21. Similarly, the side surface 23 of the area to be processed 21, after polishing, becomes a fine surface 25, also possessing the fine texture 32.

[0035] Based on the above summary, step b polishes the area to be processed 21, transforming the original rough texture into a fine texture 32, so that the mold blank 20 has fine surfaces 24 and 25.

[0036] By comparing the specific photographs or diagrams in Figures 3-7 with the second processing method in Figure 2, we can more intuitively understand the differences before and after step b:

[0037] First, step b uses a polishing process to roughen the rough texture of step a to a fine texture 32 of 3mm to 0.1mm, so that the mold blank 20 has fine surfaces 24 and 25.

[0038] Next, in step c, the fine surfaces 26 and 27 are finished as smooth surfaces using either magnetic or vibratory grinding methods, resulting in an average surface roughness (Ra) of 0.2µm to 0.025µm for the smooth texture 34. In some embodiments, the average surface roughness (Ra) of the smooth texture 34 is between 0.1µm and 0.025µm.

[0039] After processing, the mold blank 20 becomes a finished mold (not shown). High-temperature thermoplastic material flows into the processing area 21 and cools to form a solid plastic product. Because the smooth surfaces 26 and 27 are approximately mirror-like, the contact area between the finished product and the mold is small, the frictional resistance is relatively reduced, and the finished product can easily detach from the mold.

[0040] Without departing from the broad concept of this case, those skilled in the art can understand and modify the above-described embodiments. Therefore, this case is not limited to the specific embodiments disclosed in the specification, and all modifications made in accordance with the spirit and technical scope of this case should be covered and protected by the textual content defined in the patent application.

[0041] 10: Prepare the mold blank 12: Mold Surface Processing 14: Smooth Surface Processing 20: Mold blank 21: Processing Area 22: Bottom surface 23: Side view 24, 25: Fine noodles 26, 27: Smooth surface 30: Rough texture 32: Fine texture 34: Smooth texture

Claims

1. A method for processing a smooth surface of a plastic mold, comprising the following steps: step a): providing a mold blank (20) with a rough texture (30) on a processing area (21); and step c): using one of two grinding methods, magnetic force or vibration, to finish the surface of the processing area (21) with a rough texture (30) into a smooth surface (26, 27) with a smooth texture (34).

2. The method for processing the smooth surface of a plastic mold as described in claim 1, wherein, The area to be processed (21) in step a) has rough texture (30) of 3 mm or more; in step c) the rough texture is processed into smooth texture (34) to obtain an average surface roughness (Ra) between 0.2 µm and 0.025 µm.

3. The method for processing the smooth surface of a plastic mold as described in claim 2, wherein, The average surface roughness (Ra) of the smooth texture (34) is between 0.1µm and 0.025µm.

4. A method for processing a smooth surface of a plastic mold, comprising the following steps: Step a): providing a mold blank (20) with a rough texture (30) on a processing area (21); Step b): polishing the surface of the processing area (21) with the rough texture (30) to a fine surface (24, 25) with fine texture (32); and Step c): using one of two grinding methods, magnetic force or vibration, to finish the fine surface (24, 25) of the processing area (21) with fine texture (32) to a smooth surface (26, 27) with smooth texture (34).

5. The method for processing the smooth surface of a plastic mold as described in claim 4, wherein, Step a) The area to be processed (21) has rough textures of 3 mm or more (30); Step b) The rough textures are processed into fine textures of 3 mm to 0.1 mm (32); Step c) The fine textures are processed into smooth textures (34) to obtain an average surface roughness (Ra) between 0.2 µm and 0.025 µm.

6. The method for processing the smooth surface of a plastic mold as described in claim 5, wherein, The average surface roughness (Ra) of the smooth texture (34) is between 0.1µm and 0.025µm.

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