JPS583458B2 - Press mold manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a press mold used for manufacturing large press products (for example, automobile bodies).

For example, when manufacturing special vehicles whose production numbers are limited, it would be extremely expensive to use the press molds used for mass-produced models, so concrete molds, which are being developed recently, are used. It is desirable to use a simple press mold with a mold body.

By the way, in such small-scale production, there are cases where a predetermined number of car bodies etc. are manufactured at one time and then no production is made at all.
Depending on orders, production may be resumed after several years.

Therefore, in the latter case, even if the press die is simple, it is required that the precision does not deteriorate over a considerable period of time.

The present invention aims to improve this type of press mold in order to meet such demands, and its main purpose is to improve this type of press mold so that the concrete mold body formed inside the frame shrinks or expands due to aging. The objective is to manufacture a press die that does not impair the precision of the press die.

An embodiment of the present invention will be described below with reference to the drawings. Figs. 1 to 3 show an example of a press mold to be manufactured by the present invention, which is used for press working the fender of a small truck. In the figure, symbol E indicates an upper die attached to a ram of a press machine (not shown), and symbol G indicates a lower die placed on press die J.

Further, reference numeral H indicates a double-action type blank holder, and this blank holder H is attached to the side of the upper die E so as to be relatively slidable in the vertical direction. Prior to the lowering, it descends and presses and holds the peripheral edge of the flat plate-shaped workpiece on the wrinkle pressing surface g of the lower die G by means of the wrinkle pressing surface h.

In this embodiment, the upper mold E has substantially the same configuration as the lower mold G, so the configuration of the lower mold G will be described below.

As shown in FIGS. 1 and 3, the lower mold G includes a box-shaped frame body 20 made of two pairs of steel plates 2L 22 (thickness: 3 to 10 mm) each having a predetermined shape and size. Frame body 20
As shown in FIG. 1, a synthetic resin layer 30 having a press die surface 31 is formed at the upper end thereof.

A concrete mold body 6 is attached to the lower side of this synthetic resin layer 30 through a concrete adhesive resin layer 61 within the frame 20.
0 is cured in a sealed state, and on the other hand, cast iron blocks 41 to 50 are disposed on the upper surface of this synthetic resin layer 30 around the press die surface 31, and each block 41 to 50 A wrinkle pressing surface g is formed on the outer periphery of a large number of piano wires P.

Further, a bottom plate 23 made of a steel plate is provided at the lower end of the frame 20 in the drawing.
The concrete mold body 60 is sealed from below and fixed with concrete adhesive resin, and a resin layer 24 is adhesively formed on the lower surface of the bottom plate 23 for horizontally placing the lower mold G on the press stand J. has been done.

Note that in FIGS. 1 and 3, each reference numeral 25 indicates a hanging bolt, and in FIGS. 1 and 2, each reference numeral 26 indicates a mounting plate.

These mounting plates 26 are integrally fixed horizontally to the lower end corners of the concrete mold main body 60 at predetermined intervals by connecting reinforcing bars 27, and each mounting plate 26 has its mounting portion 26
It is fixed onto the press stand J with each bolt 28 at a.

As shown in FIG. 1, the synthetic resin layer 30 is constructed by integrally forming a bonding resin layer 34 on the lower surface of a surface resin layer 33 having a relatively gently curved press die surface 31.

The surface resin layer 33 is formed by adding an appropriate amount of curing agent to liquid epoxy resin and curing it, and has high pressure resistance and abrasion resistance, and has small curing distortion and temperature distortion, and is resistant to deterioration over time. .

As a result, the press mold surface 31 is sufficiently effective as a mold surface that does not cause stress concentration during pressing, and is suitable for mass production and has relatively high processing accuracy.

The bonding resin layer 34 is made by adding an appropriate amount of a hardening agent to a liquid epoxy resin, and then adding a predetermined amount of quartz powder (for example, 2.5 times the amount of the epoxy resin to which the hardening agent has been added) and curing the mixture. The pressure transmitted through the surface resin layer 33 during pressing is effectively dispersed and transmitted to the mold body 60.

As shown in FIG. 3, the cast iron blocks 41 to 50 are arranged along the periphery of the press mold surface 31, and
As shown in FIG. 1, the lower portions of each of these blocks 41 to 50 are firmly held from below by a portion of the surface resin layer 33 located around the press mold surface 31.

Thereby, the stepped portion formed by the cast iron blocks 41 to 50 around the press mold 31 will not be destroyed during press working.

Further, each of the cast iron blocks 41 to 50 is formed of a substantially rectangular parallelepiped casting, and its inner corner portions 41a to 50a are finished to correspond to the stepped portions of the workpiece.

These cast iron blocks 41 to 50 are formed into as simple a shape as possible in order to save molding costs and to facilitate mutual adjustment of the blocks, and are divided into linear steps, each of which has a length. The length is set to 400 mm or less to reduce deformation strain.

In this case, among the cast iron blocks 41 to 50, both joint end faces of the blocks 43, 45, and 48 arranged in a straight line or a nearly straight line around the press mold surface 31 are given a predetermined finishing allowance. Blocks 41, 42, 44 formed in a tapered shape and arranged in a curved part around the press mold surface 31,
46, 47, 49.50 are formed by providing only the minimum machining allowance.

Therefore, when finishing the joint end surfaces of the entire blocks 41 to 50, a spotting model (not shown) is used to finish the blocks 41, 42, 44, 46,
47, 49.50 can be easily finished in a short time, and the remaining blocks 43, 45.48 can be finished with great accuracy.

This shortens this finishing work.

In addition, in this finishing work, the cumulative error that occurs when arranging the blocks 41 to 50 around the press mold surface 31 is mainly corrected by arranging them in a straight line part or a part close to a straight line around the press mold face 31. When finishing the tapered joint ends of the blocks 43, 45, and 48, this can be absorbed by simply adjusting the length, which simplifies the finishing work.

As shown in FIG. 3, the wrinkle pressing surface g is
A large number of piano wires P (diameter: approx. 3 mm) of a predetermined length are arranged horizontally in upper and lower layers along the outer periphery of the piano, and are fixed by applying epoxy resin. The line P is firmly held from below by a part of the surface resin layer 33 located on the outer periphery of each block 41-50.

Therefore, the wrinkle pressing surface g has excellent pressure resistance and abrasion resistance.

Moreover, in this case, each piano wire P is arranged so that a portion of the workpiece located on the wrinkle pressing surface g has an angle of 100 or more with respect to the direction in which it is pulled during pressing.

Therefore, on this wrinkled holding surface g, each top surface bites into the workpiece in order to clamp and press the workpiece between each end surface of each piano wire P and the wrinkled holding surface h of the blank holder H. Since the axial direction of each piano wire P and the direction of the workpiece that is pulled during pressing intersect, each piano A large frictional force can be obtained by the line P, and the wrinkle pressing function of the wrinkle pressing surface g can be improved.

The concrete mold body 60 is made by mixing cement with a predetermined amount of river sand (for example, three times the amount of cement), and pouring the mixture into the frame 20 in a state containing the required amount of moisture and keeping it sealed. The reinforcing reinforcing bar 62 is integrally included in the upper part of the reinforcing bar 62.

The mold main body 60 configured in this way plays a role in maintaining the rigidity of the entire lower mold G, and has a maximum pressure resistance of 400 kg/cm. It is designed to sufficiently absorb the pressing force transmitted through the material and to withstand repeated use.

Moreover, since the mold body 60 is cured while the concrete is poured into the frame 20 and kept sealed, the moisture contained in the concrete does not evaporate and effectively acts on the hardening of the mold body 60.

Therefore, the strength of the mold body 60 is further increased, and the shrinkage deformation of the mold shape is extremely small.

To explain the manufacturing process of the lower mold G configured as above, in manufacturing the lower mold G, as shown in FIG. A mold model 70 is manufactured in advance.

In addition, the above-mentioned cast iron blocks 41 to 50 are manufactured in advance using a predetermined mold, and corners 41a to 50a (see Fig. 3) corresponding to the steps of the workpiece of each of these blocks 41 to 50 are formed. The joint end faces of each block 41 to 50 are finished to a predetermined accuracy and using a predetermined spotting model.

First, the cast iron blocks 41 to 50 are respectively joined and disposed on the stepped portion 73 along the periphery of the mold surface 71 of the mother mold model 70.

Thereafter, the steel plates 21 and 22 are framed vertically and in a box shape on the upper surface 72 of the matrix model 70 located around the mold surface 71, as shown in FIGS. 3 and 4, so that they are adjacent to each other. The frame body 20 is made by arc welding the peripheral parts of each steel plate 21 and 22.
form.

In this case, a plurality of hanging holders 2 are provided at predetermined positions of the pair of steel plates 22 and 22, as shown in FIGS. 3 and 4.
Attach step 5 in advance.

In addition, after the frame erection is completed, clay e is applied from the outside along the joint between the lower end of the frame 20 and the upper surface 72 of the matrix model to position the frame 20 and to prepare it in the subsequent process. Epoxy resin poured into the frame 20 is prevented from flowing out.

Next, to explain the process of forming the wrinkle pressing surface g, a small amount of liquid epoxy resin is applied in advance to the upper surface 72 of the matrix model 70 on which the wrinkle pressing surface g is to be formed, and then a large number of piano wires P are applied. , on the undercoat portion of the epoxy resin along the outer periphery of each block 41 to 50 at an angle of 10 degrees or more to the direction in which the peripheral edge portion of the workpiece located on the wrinkle pressing surface g during pressing is pulled, As shown in FIGS. 3 and 5, the epoxy resin is further applied with a brush to the extent that the lower half of each piano wire P arranged in upper and lower layers is covered, and the wrinkle pressing surface g is formed. complete.

Immediately after completing the formation of the wrinkle pressing surface g as described above, epoxy resin to which an appropriate amount of curing agent has been added is applied to the mold surface 71 of the mother mold model 70 and the cast iron block 41 as shown in FIG. ~50, Apply with a uniform brush to a thickness of 2 to 5 mm so as to cover each piano wire P constituting the wrinkle pressing surface g and the upper surface 72 of the matrix model 70 located on the outer periphery of the wrinkle pressing surface g. A surface resin layer 33 is formed, and then a liquid epoxy resin mixed with an appropriate amount of hardening agent and a predetermined amount of quartz powder is applied to the upper surface of the surface resin layer 33 to a thickness of about 20 mm to bond it. A resin layer 34 is formed, and the formation of the synthetic resin layer 30 is completed.

After this is completed, the bonding resin layer 34 is left as it is for a predetermined period of time and when it becomes a semi-hardened state, the concrete adhesive resin is uniformly applied to the upper surface of the bonding resin layer 61 so that there is no uncoated area. Immediately after forming, the process of pouring the concrete mold body 60 begins.

The concrete adhesive resin layer 61 is water resistant and impermeable, and prevents moisture contained in the concrete mold body 60 from coming into contact with the synthetic resin layer 30.

Thereby, the synthetic resin layer 30 forms a predetermined molding surface without hindering the desired curing process.

Next, to explain the process of pouring the concrete mold body 60, concrete mixed with an appropriate amount of water (cement 1
As shown in FIG. Long reinforcing bars 62 on the top surface
Thereafter, a predetermined amount of concrete is further laminated inside the frame 20.

In this case, the concrete is layered higher than the illustrated upper end of the frame 20 in order to float as much excess water contained in the concrete as possible.

Additionally, in order to prevent strain from occurring in the synthetic resin layer 30,
It is desirable to complete the concrete layering before the synthetic resin layer 30 hardens.

Next, the concrete located near the inner circumferential surface of the upper end of the frame 20 as shown in the figure is gathered toward the center to form a recess along the inner circumferential surface of the upper end of the frame 20, and plaster is poured into this recess. When the concrete has almost hardened, remove the plaster and concrete that protrude upward from the upper end of the frame 20, place the bottom plate 23 made of a steel plate horizontally on the upper end of the frame 20, seal the concrete, and make a concrete mold. The driving of the main body 60 is completed.

In this case, concrete adhesive resin is applied to the inner surface of the bottom plate 23 in advance in order to improve adhesion to the concrete.

After completing the casting of the concrete mold body 60 in this way, a weight (not shown) is placed on the top surface of the bottom plate 23.
is placed on the concrete mold body 60 and the synthetic resin layer 30 is applied with this weight, thereby shaping the synthetic resin layer 30 into a desired molded shape without causing hardening distortion, especially shrinkage distortion in the plane direction. Let it harden.

After the solidification and expansion of the concrete mold body 60 is almost completed (after about 24 hours have elapsed after the completion of mold formation of the mold body 60)
Then, the weight is removed and the upper surface of the bottom plate 23 as shown in the figure is cleaned, and a concrete adhesive resin is applied between the upper end of the frame 20 and the peripheral edge of the bottom plate 23 to prevent moisture in the mold body 60 from evaporating.

Then, leave it in this state for at least 3 days.

After leaving the lower mold G for a predetermined period of time, the lower mold G is removed from the mother mold model 70 and turned upside down, and the lower mold G is placed on a horizontal surface plate using a jack L via each hanging bolt 25, as shown in FIG. The bottom plate 2 is supported horizontally on K at a predetermined height.
A liquid epoxy resin is poured between the upper surfaces of the bottom plate 3 and the horizontal surface plate K, and a resin layer 24 for horizontally placing the lower die G on the press table J is integrally formed and hardened on the outer surface of the bottom plate 23. Then, the production of the lower mold G is completed.

The lower mold G manufactured in this way is made of concrete mold body 6.
0 is used while being sealed between the frame body 20 and the bottom plate 23.

As described above, in this embodiment, since the concrete forming the concrete mold body 60 is poured into the frame 20 and cured in a sealed state, the concrete mold body 60 is By preventing moisture from dissipating, it is possible to sufficiently harden the concrete, thereby suppressing volumetric distortion of the concrete mold body 60 due to drying shrinkage or aging.

In addition, when manufacturing the above-mentioned lower mold G, the concrete mold main body 60 may be formed of two concrete layers, for example, in order to shorten the time of use after the formation of the lower mold G is completed. In some cases, the upper concrete layer (
The layer (formed directly below the concrete adhesive resin layer in Figure 1) is formed from concrete made by mixing early strength cement with the same amount of silica sand and an appropriate amount of water, and the lower concrete layer is formed using the above method. It may be formed from the concrete used in the example.

Further, in the above embodiment, an example of manufacturing a lower mold was shown, but it goes without saying that the present invention can also be applied to manufacturing an upper mold, and the same effects as in the case of the lower mold can be obtained.

As explained above, the present invention provides a method for manufacturing a press mold comprising a synthetic resin layer having a press mold surface on the surface and a concrete mold main body integrally fixed to the synthetic resin layer, in which the concrete mold main body is The manufacturing feature is that the concrete to be formed is poured into the frame and allowed to harden while being sealed.

Therefore, according to the present invention, after concrete is poured into a frame, sufficient hardening can be achieved by preventing the moisture contained in the concrete from dissipating, thereby reducing the volume of the concrete mold body due to shrinkage, expansion, etc. due to aging. It is possible to manufacture a press die that can suppress distortion and does not impair the precision of the press die.

[Brief explanation of the drawing]

FIG. 1 shows a press mold embodying the present invention, and in the figure, the lower mold is cut along the line 1--1 in FIG. Figure 2 is a partial sectional view taken along line 2-2 in Figure 1, Figure 3 is a plan view of the lower mold shown in Figure 1, and Figures 4 to 7 are the
It is a sectional view showing the manufacturing process of the lower die shown in the figure. Explanation of symbols, 20...frame body, 30...synthetic resin layer,
31...Press mold surface, 60...Concrete mold body.

Claims (1)

[Claims] 1. Forming a synthetic resin layer on the mold surface of a matrix model that forms the press mold surface, and pouring concrete into a frame erected around the matrix model to form a concrete mold body, In a method for manufacturing a press mold comprising a synthetic resin layer having a press mold surface on its surface and a concrete mold body integrally fixed to the synthetic resin layer, concrete forming the concrete mold body is poured into the frame. A method for manufacturing a press mold, which is characterized by curing the press mold in a sealed state.