JPS59209429A - Core die for forming bend and removing of core die after forming bend - Google Patents

Abstract

PURPOSE:To reduce drawing resistance and to improve accuracy of products by dividing a core die by a dividing face along the direction of curvature of the core die into two segmental core dies having different positions of center of gravity and drawing by turning each segmental core die turning them in opposite direction toward respective deviation sides of center of gravity. CONSTITUTION:In cross section of center axis of a core die, an imaginary face ABB'A' connecting two circles along the edge line of the core die that are drawn by setting perpendiculars Ra, Rb drawn from two points A, B at which an arbitrary center line passing the center Q of axis of the core die intersects the outer peripheral line of the core die as the center axis P-P' of curvature of the core die radius of curvature, and setting the center axis of curvature of the core die P-P' as centers. The core die for forming bend is bisected by a plane 4l which is made by rotating by optional angle making a line XlYl which is contained in the imaginary face ABB'A' and perpendicular to a tangent at any point on the circumference of a circle including the center axis OO' of the core die. These segmental core dies are rotated in opposite direction toward respective deviation sides of center of gravity and drawn by turning.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to bent pipe forming, and more particularly to a core mold that can be easily removed after forming a bent pipe, and a method for removing the core mold.

An important issue when molding bent pipes is how to successfully remove the molding core after molding, and various methods have been used to date. For example, there is a method in which a core mold for molding is formed of plaster and the core mold is dismantled when molding is completed. This method is not economical because it requires as many core molds as there are curved pipes to be molded. Next, there is a method of dividing the core mold in the circumferential direction to reduce its diameter and pulling it out, but this method is mechanically complicated and requires time and effort to disassemble and remove the core mold, which is also not efficient. - A relatively simple method is to taper the outer periphery of the core mold in the full + direction (the diameter of the core mold is gradually reduced very slightly from one side to the other, and the core mold is tapered toward the larger diameter side. There is a method of pulling out the core mold, but because the precision of the dimensions of the molded product is required, the above-mentioned punching tool cannot be removed very much, and therefore the resistance until it is pulled out is large.If the resistance is high, it takes time and effort to remove the core mold. Not only that, but the resistance during removal can cause cracks on the inner surface of the bent tube, which can easily cause problems with the quality of the bent tube.As mentioned above, conventional methods for removing molding cores Due to this problem, there was an urgent need for the development of a molding core mold that was satisfactory in terms of quality and that could be easily pulled out, as well as a method for pulling it out after molding.

The present invention was made as a result of research to solve the above problems, and has a simple structure, low resistance to pulling out,
Moreover, it is an object of the present invention to provide a core mold for forming a curved pipe and a method for removing the core mold in the method of forming a curved pipe, using an extremely simple principle that does not impair the viscosity of the molded product.

In the present invention, which has achieved such objects, firstly, the core mold for curved injection molding is a core mold for curved tube molding that is divided into two parts in the axial direction, and the core mold is divided into two parts in the axial direction, and the core mold is divided into two parts in the axial direction. A perpendicular line drawn from two points where an arbitrary center line passing through the center of the mold axis intersects with the core mold outer circumferential line to the core mold curvature center axis is used as a curvature radius along two core mold ridge lines drawn around the core mold curvature center axis. A virtual plane connecting the circles is divided into two by a plane rotated by an arbitrary angle using a line included in the virtual plane and perpendicular to a tangent at an arbitrary point on the circumference including the center axis of the core as a reference line. The method of forming a curved pipe on the outer periphery of a core mold for forming a curved pipe and then pulling out the core mold is a method of forming a curved pipe by pulling out the core mold in the direction of curvature of the core mold. The gist of this method is to divide the core into two split core molds with different center of gravity positions depending on the split surface along which they pass, and to unscrew each split core mold while turning in mutually opposite directions toward the side where the center of gravity is deflected.

The configuration and effects of the present invention will be explained below in detail based on the drawings showing the embodiments. However, the embodiments below are only one specific example, and the design may be modified in various ways in keeping with the spirit described above and below. All are included within the technical scope of the present invention.

First, the principle of dividing the core mold in the present invention will be explained.

Figures 1 and 2 are side views of the core mold 1 divided into split molds 1a and lb, with the curved tube 2 coated on the outer periphery, as seen from the horizontal direction, and 3 and 3' are cores. The dividing line appearing on both the left and right end surfaces of mold 1, 4 separates core mold 1; 'at mold 1a, Ib
Shows the dividing plane. Note that point Q in FIG. 2 is the center point of the core mold 1 in a cross-sectional view perpendicular to the central axis, and is also a point at the center in the length direction of the core mold l (i.e., the center point of the core 4 (vl) and the center of gravity. ).In the example in Figure 1.2, the core type is split line 3.
, 3' are made perpendicular to the center axis of core curvature (described in detail later), and at the same time, i+i! The L-types 1a and Ib are irregular on both left and right end surfaces, and in the example shown in Fig. 1, the split-type +a,
lb have different shapes, but in the example shown in Fig. 2, the split surface 4 passes through the center point Q, so the split molds 1a and Ib are the same.
It is symmetrical in shape. In addition, FIG. 3 is an explanatory view showing the core type in FIG.
It is now 4. Strings for forming the split surface in this way 1. This will be explained in detail later, but in any case, by adopting the structure as described above; ;u 6sl
The center of gravity i+'i of a and Ib is divided to the left and right of point Q, and for example, in FIG. 4, it moves to the position IM of Wa and Wb.

In addition, this state corresponds to the area Sa of the left end surface of the divided mold 1a being larger than the area Sa' of the right end surface, and for the divided mold 1b, the area sb of the right end surface is larger than the area sb of the left end surface. It corresponds to becoming. The split surfaces 4 face each other in a tapered manner, and this taper continues smoothly from the small area side end face to the large area side end face. Therefore, when the split mold 1d is pulled out in the direction of arrow A and the split mold 1b is pulled out in the direction of arrow B (this extraction is done by turning as shown by arrows A and H in FIG. 3), the split surface 4 becomes as shown in the figure. In the 11th year of high school, we moved in the direction of becoming separated,
A space 5 is created between the divided mold 1a and the divided mold 1b. By forming this space 5, the initial divided molds 1a, lb
are integrated, and the force pressing the core mold 1 against the pipe wall of the curved pipe 2 is eliminated, and the frictional resistance between the divided molds 1a, 1b and the curved pipe wall becomes so slight that it can be substantially ignored. In other words, this means that the diameter of the split molds 1a and 1b has been reduced by the gap in the space 5 in the radial direction of the curved pipe 2. This temporary diameter reduction phenomenon reduces the resistance when the molding core 1 is unscrewed from the curved tube 2, making it easier to unscrew it. Incidentally, it is of course possible to carry out diameter reduction and extraction while maintaining the split surface 4 of the two-core type in a sliding state.

5 to 7 are explanatory diagrams expressing the present invention in perspective.

First, regarding the formation of a virtual surface as a preliminary step for forming the split surface 4, in FIG.
+ Any center line passing through the center point (corresponding to any one point on the circumference including the center axis o - o' of the core type) in the cross-sectional view shown by cutting O-o' at a right angle 1ζrB is the core. Hikone the two intersections A and B that intersect with the outer circumferential line of type l. This intersection A
, B appears at any point on the outer periphery of the core mold,
In the figure, for ease of understanding, A is placed on the left end surface of the core mold.
A′ is shown on the right end surface as B and corresponds to this.
, B'. The line segments AB and A'B' are shown as horizontal lines in the figure. Therefore, the intersections A and B
When a perpendicular line is drawn from to the core-shaped curvature center axis P P', the intersection of the perpendicular line and the center Il:I+ coincides at one point Oa. Then, the perpendicular lines AOa and BOa become the radius of curvature Ra and Rb, respectively (
Furthermore, the connecting lines A'Oa and B' [even considering la, the length of the front beach is Ra, and the length of the rear beach is Rb). Next, centering on Oa, Ra.

Line segments AA' and BB' are determined by drawing a circle along the ridgeline of core type 1 with Rb as the radius of curvature. And two wood bullets AA
By connecting ', BB' and the center lines A B and A'B' of the two trees, a part of the virtual surface ABB'A' is shown.

"2, Figure 5 (A) is 1. This was an example in which a virtual plane perpendicular to the central axis of curvature PP' was formed by selecting the center line AB as a horizontal line.
The figure shows an example in which intersection points C and D forming a virtual plane CD D'C' parallel to the central axis of curvature PP' are selected. That is, the intersection point between the perpendicular line drawn from point C to the central axis of curvature PP' of the core type and the center axis is OC, while the intersection point between the perpendicular line drawn from point C to the same central axes P and P' and the center axis is Od. Then, let COc and DOd be radii of curvature Rc and Rci, respectively, and the intersection OC
By drawing a circle with radii of curvature of Re and Rd centered on and Od, lines CC' and DD' are similarly obtained on the core mold 1, and a portion of the vertical virtual plane CDD'C' is obtained. Also, for the virtual plane E'F F'E' in Figure 7(A), we selected the intersections E and F that form a virtual plane located at an intermediate position between Figures 5(A) and 6(A). An example is shown. Symbol Oe, O
f, Re, and Rf can be considered in the same manner as described above.

Next, the formation of the ^1j curved surface 4 will be explained. Fifth (B)
In the figure, part A of the virtual surface obtained in FIG. 5(A) is shown.
BE'A' is represented by a broken line, and the line segment Ye, which is included in the virtual plane and passes through the center point Q and is perpendicular to the tangent at point Q to the central axis 00' of the core type, is used as a reference line. angle(
In the figure, the core mold of the present invention is constructed by rotating the core 4a to form a splitter 4a and dividing it into two parts at the angled surface 4e. In the example of FIG. 6(B), the sixth (A
) Part of the virtual surface obtained in the figure CD
By rotating the line segment XpYp perpendicular to the tangent at the point as a reference line by an arbitrary angle (0 in the figure), the split surface 4p is formed. It is formed. 7th (B)
In the example shown in the figure, a part of the virtual surface obtained in FIG. 7(A) E F
By rotating F'E' by an arbitrary angle (0 in the figure) based on the same line segment XaYa as in the previous two examples, a splitting surface 4a is formed, and by dividing the splitting surface 4a into 2 parts. The core mold of the present invention is formed.The reference line for rotation in the example shown in FIG. .

On the other hand, in the example of Figure 1.3, the fifth (B), sixth (B), and seventh
(B) This is an example in which the reference lines XIYI, XpYp, and XaYa shown in the figure do not pass through the center point Q.

In the case of this example, a line segment that is included in the virtual surface and perpendicular to the tangent at any point (excluding Q) on the circumference that includes the center axis 00 of the core type is applied as the reference line for rotating the virtual surface. It is something. In other words, the rotation reference line is selected at the core center 8+I.
It is easy to select any point on the circumference that includes IOO',
Core type central axis OO at any point included in the virtual plane
' can satisfy the present invention.

The core mold 1 for molding, which is divided into two parts by the split surface 4, has a simple structure, has low pulling resistance, and has a curved shape that makes full use of an extremely simple principle that does not impair the precision of the molded product. It can be called a core mold for tube forming.

Since the present invention is constructed as described above, there is extremely little pulling resistance when pulling out the molded core mold of curved bamboo.
It was possible to provide a simple core mold for forming a curved pipe and a method for removing the core mold after molding without impairing the precision of the molded product. Furthermore, by using the core mold for molding of the present invention, the following effects were also obtained. In other words, there is no need to create a taper on the contact surface with the curved pipe to be formed, so it is possible to create a curved pipe. The inner diameter dimension viscosity of No. 11 was also good, and the conventional core mold for forming curved pipes, which could not be reduced in diameter unless it was a hollow type, could now be used with a central type.

[Brief explanation of the drawing]

1 and 2 are side views of a curved pipe and a core type to explain the present invention in detail, 3 and 4 are explanatory diagrams perspectively expressing FIG. 1, and 5 (A) and (B) , No. 6(A). (B) and 7th (A) and (B) are explanatory diagrams expressing the present invention in perspective. l...Molding core mold 1a, Ib...Divided mold 2.
...Curved pipe 3...Split line 4...Split surface
5... Space Q... Center point 00 Te... Core type central axis pp<... Core type curvature central axis Applicant: Kubota Iron Works Co., Ltd. 1'' Hon Shokubai Kagaku Kogyo Co., Ltd. Figure 7 (A) Osaka 5-1 Koraibashi, Higashi-ku, City

Claims (2)

[Claims] (1) A core mold for curved pipe forming that is divided into two parts in the axial direction, from two points where an arbitrary center line passing through the core axis center intersects with the core outer circumferential line in a cross-sectional view at right angles to the core center part 11. Core type curvature center! : An imaginary plane connecting the circles along the two core ridge lines drawn with the perpendicular drawn to j as the radius of curvature and centered on the center axis of the core curvature is included in the virtual surface, and 11 is the center axis of the core. A core mold for forming a curved pipe, which is divided into two by a plane rotated by an arbitrary angle using a line perpendicular to a tangent at an arbitrary point on the circumference as a reference line. (2) Song? After forming a curved pipe around the outer periphery of the j1 molding core,
When drawing out the core mold to form a curved pipe, the core mold is
The core 4 is divided into two split core types with different center of gravity positions depending on the split surface that heals in the curvature direction, and each split core J (11 is turned toward the center of gravity deflection side) and rotated in opposite directions. A method for removing the core after forming a bent pipe.