JP3368928B2 - Extrusion mold manufacturing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an extrusion die in which resin chips are prevented from adhering to the tip of a lip of the extrusion die. 2. Description of the Related Art As a method for suppressing the generation of resin chips (hereinafter referred to as lip scum) adhering to the tip of a lip of an extrusion molding die, a non-adhesive resin layer is formed on the lip surface. Known (for example, Japanese Patent Application Laid-Open No. 56-9563)
7, JP-A-58-12743). But,
This method applies a non-stick resin to the lip surface,
Or a special process of attaching is required. [0003] Japanese Patent Application Laid-Open No. Hei 2-261622 discloses that a non-adhesive resin layer is not formed on the surface of a lip.
The angle between the surface of the resin flow path at the tip of the lip and the outer surface of the lip is set to approximately 90 °, and the ridgeline where the surface of the resin flow path at the tip of the lip and the outer surface of the lip intersect is subjected to rounding or chamfering. An extrusion mold has been proposed which uses a non-lip and incorporates it into the mold body. Conventionally, as a method of finishing the surface of the lip, a method of using a surface grinder to grind and finish the surface of the resin flow path at the tip and the outer surface of the lip with a grindstone (further buffing as necessary) And a method in which the side surface of the resin flow path at the tip end and the outer surface of the lip are processed by a milling machine or the like, and then buffed. [0005] However, in the former surface grinding method, since the sand particles of the grindstone are ground substantially in parallel to the direction of the ridge portion, chipping and burrs are liable to occur at the ridge line portion. In addition, there is a problem that the appearance of the film to be extruded is poor due to streaks and the like. Further, in the buffing method, the radius is easily generated at the ridge line portion, and therefore, although there are few streaks in the film to be extruded, there is a problem that generation and deposition of lip scum cannot be suppressed. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and when finishing a lip, a ridge portion where a resin flow path surface at the tip of the lip intersects with an outer surface of the lip is chipped or a burr remains. Production of an extrusion mold that suppresses the occurrence of lip scum and does not cause appearance defects such as streaks on the surface of the film to be extruded. Aim. [0007] A method of manufacturing a die for extrusion molding according to the present invention includes a grinding step of grinding and finishing a resin flow path side surface and an outer surface of a lip of a lip member, and finishing by the grinding step. Incorporating the applied lip member into the tip of the mold body, the method for manufacturing a mold for extrusion molding,
The grinding step uses a grinding wheel with the flat surface of the disc-shaped body as a grinding surface, and the grinding wheel and the lip member are ridge lines of a ridge portion where the resin flow path side surface of the lip member and the lip outer surface intersect. A process of relatively moving the grinding wheel in a direction substantially parallel to the direction and rotating the grinding wheel in a direction in which a front portion of the grinding wheel relative to the lip member in the moving direction side moves away from the ridge line of the lip member. This achieves the above object. It is preferable that a concave portion can be formed in a part of the grinding surface of the grinding wheel, so that a part of the ground cutting powder is stored in the concave portion. In the cutting step, the grinding surface of the grinding wheel is parallel to the surface to be ground of the lip member, and the grinding direction of the abrasive grains is in the relative movement direction of the ridge line of the lip member and the grinding wheel. It is at right angles or oblique directions, and most of the swarf is removed from the ground surface. Further, since the grinding wheel is rotated so that the front portion in the relative movement direction of the grinding wheel moves away from the ridge line of the lip member, the pressing force against the ridge line portion of the grinding wheel is reduced. And the ridge is prevented from being chipped. Next, a method for manufacturing an extrusion mold according to the present invention will be described with reference to the drawings. In the grinding step in the method of the present invention, a grinding apparatus as shown in FIG. 2 is used. In FIG. 2, reference numeral 1 denotes a lip member as an object to be ground, 2 denotes a grinding wheel, 3
Reference numeral 4 denotes a drive unit for rotating and moving the grinding wheel 2 up and down, and reference numeral 5 denotes a bed for mounting and fixing the lip member 1. The lip member 1 is cut into a lip shape, and a resin flow path side surface 11 and a lip outer surface 12 are formed. The bed 5 can be moved by a moving device (not shown) substantially parallel to the ridge line 13 of the lip member 1 placed and fixed thereon. As shown in FIG. 3, the grinding wheel 2 comprises a disk-shaped grinding wheel body 21 and a core rod 22 for holding it on the chuck 3. Flat surface 2 of this disk-shaped grinding wheel body 21
Reference numeral 3 denotes a cutting surface, and a concave portion 24 is formed at the center thereof. As another example of the grinding wheel 2a, as shown in FIG. 4, a plurality of grooves 25 are formed on a flat surface 23a of a disc-shaped grinding wheel body 21a so as to communicate with a concave portion 24a. Is also good. These grooves 25, 25... Serve as guide paths for guiding the grinding chips to the recess 24a. Note that the grinding wheels 2, 2
The diameter of the ground surface a is preferably larger than the width of the ground surface, and is usually about 1.1 to 1.5 times, more preferably 1.1 to 1.25 times the width of the ground surface. It is about double. Next, the grinding process will be described with reference to FIGS. The lip member 1 is placed and fixed on the bed 5 with the side surface 11 of the resin flow path, which is the surface to be ground, facing upward. Then, the grinding wheel 2 is moved by the driving device 4 so that the grinding surface thereof is the resin flow path surface 1.
1 and lowered to the cutting position. Subsequently, while rotating the grinding wheel 2, the bed 5 is moved, and the lip member 1 is moved in a direction parallel to the ridge line of the ridge line portion 13 (the direction of the arrow in FIG. 1). The rotation of the grinding wheel 2
The grinding wheel is rotated such that the front portion A in the relative movement direction is away from the ridge line 13 of the lip member 1 (the direction of the arrow in FIG. 1). Next, the lip member 1 is placed and fixed on the table 5 with the lip outer surface 12 facing upward, and the lip outer surface 12 is ground in the same manner as described above. Thus, the resin flow path surface 11 and the lip outer surface 12 of the lip member 1 are ground. It should be noted that the rotation of the grinding wheel is relatively low, and is preferably set at 1200 revolutions / minute or less. The lip member finished through the above-mentioned grinding step is incorporated into the tip of the mold body in the same manner as in the prior art to obtain a mold for extrusion molding. Next, a specific example of the above method will be described. A lip member cut into a lip shape with the material SCM440 (hardness HRc23) was ground and finished by the above method. The material of the grinding wheel is White Alundum (WA)
No. 100 abrasive grains, and the diameter of the ground surface is 1.
The number of rotations was 25 times and the number of revolutions was 1200 times per minute. The surface roughness of the resin flow path surface and the outer surface of the lip of the obtained lip member is R
When the lip member 1 is placed so that the ridge 13 is located above and the ridge 13 is observed with a stereoscopic microscope, as shown in FIG. It was confirmed that there was no chipping. The lip was incorporated into the tip of the mold body to obtain an extrusion mold having a lip interval of 3 mm, and a butyral resin film (thickness 3 mm, width 3000 mm) was extruded. No appearance defects such as scratches and scratches were generated, and no generation of lip scum was observed. For comparison, a lip member similar to the above is ground by a conventional surface grinding method as shown in FIG. 6 (the material of the grinding wheel is the same as described above), and this is assembled into a mold body and extruded. The mold was manufactured. The surface roughness of the resin flow path surface and the outer surface of the lip of this lip was Rmax 5 to 6 μm. However, when the ridge line was observed with a stereoscopic microscope, discontinuous portions of the bright line were found in some places, and the bright line width was found. Was also wider than that of the present invention. When the same butyral resin film was extruded by using this mold, the cleaning cycle ratio was 24 hours, and a number of scratches were generated in the butyral resin film. As described above, according to the method for manufacturing a die for extrusion molding of the present invention, the ridge line where the resin flow path side surface of the die and the lip outer surface intersect substantially has a radius. Does not occur,
Also, no chipping or burrs remain on the side surface of the resin flow path. Therefore, the use of this mold can suppress the occurrence of lip scum, the occurrence of streaks, and the like for a long time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing a grinding step of the method of the present invention. FIG. 2 is a front view of an example of a grinding apparatus used in a grinding step of the method of the present invention. FIG. 3 is a perspective view of a grinding wheel used in a grinding step of the method of the present invention. FIG. 4 is a perspective view of another grinding wheel used in a grinding step in the method of the present invention. FIG. 5 is an explanatory diagram of a method of inspecting a state of a ridge line portion of a lip member. FIG. 6 is an explanatory view showing a conventional grinding process example. [Description of Signs] 1 Lip member 11 Resin flow path side surface 12 Lip outer surface 13 Ridge portion 2 where resin flow path side surface and lip outer surface intersect 2 Grinding wheel 21 Grinding surface 22 Depression 23 Groove 3 Chuck 4 Drive unit 5 Bet

Claims (1)

(57) [Claims 1] A grinding step for grinding and finishing the resin flow path side surface and the lip outer surface of the lip member, and applying the lip member finished by this grinding step to the tip of the mold body. In the method for manufacturing an extrusion molding die including a step of incorporating into a part, the grinding step uses the flat surface of the disc-shaped body as a grinding surface, uses a grinding wheel, and attaches the grinding wheel and the lip member to the lip. The resin is moved relatively parallel to the ridge line direction of the ridge line where the resin flow path side surface and the lip outer surface intersect, and the front portion of the grinding wheel relative to the lip member in the direction of movement is relative to the lip line of the lip member. A method of manufacturing a die for extrusion molding, comprising a step of grinding while rotating a grinding wheel in a direction away from the mold.