CN110666101A

CN110666101A - Core-pulling method for investment precision casting wax mold back-off inner cavity

Info

Publication number: CN110666101A
Application number: CN201911093716.XA
Authority: CN
Inventors: 王树森; 王凯; 安磊
Original assignee: Shandong Senyu Precision Engineering Technology Co Ltd
Current assignee: Shandong Senyu Precision Engineering Technology Co Ltd
Priority date: 2019-11-11
Filing date: 2019-11-11
Publication date: 2020-01-10

Abstract

The invention discloses a core-pulling method for an investment precision casting wax pattern back-off inner cavity, which is characterized by comprising the following steps: firstly, manufacturing a movable sleeve type core pulling according to the shape of an inverted buckling inner cavity of a wax mould; the movable sleeve type core pulling device is characterized in that the movable sleeve type core pulling device consists of a hard inner core and an elastic outer sleeve sleeved on the hard inner core; the hard inner core is cylindrical; the shape of the elastic outer sleeve is the same as that of the back-off part at the periphery of the diameter of the cylinder; before wax injection, the elastic outer sleeve is arranged on the metal inner core and then is placed into a mould shell, and wax injection is carried out according to the traditional method; after wax injection and shaping, the hard inner core is firstly drawn out, and the elastic outer sleeve becomes an empty shell which is easy to deform and contract after losing the support of the inner core, so that the elastic outer sleeve can be conveniently taken out from the small opening of the wax mould, and the inverted-buckled inner cavity structure of the wax mould is obtained.

Description

Core-pulling method for investment precision casting wax mold back-off inner cavity

Technical Field

The invention relates to an investment casting technology, in particular to a wax pattern manufacturing technology for investment casting.

Background

In the investment precision casting industry, qualified castings need to be manufactured firstly, qualified wax patterns need to be manufactured, and then the wax patterns can be used for manufacturing the mold shells for pouring to form the castings. What structure the wax pattern is made, in other words, what pattern the cast is. The wax mould is made by using metal, injecting melted wax into the mould by using a wax injection machine, cooling, opening the metal mould, and taking out the wax mould. The wax mold is also simple to manufacture for a casting with a simple structure. However, in most cases, the most commonly used materials of the investment casting mold are aluminum and steel which are hard materials, the interior of the casting is relatively complex, a cavity with a small opening and a big opening is needed in some castings, and a wax mold also needs a cavity with a small opening and a big opening, namely the wax mold has the problem of an inverted inner cavity, and the integral common core-pulling cannot be directly pulled out of the wax mold during the manufacture of the wax mold. The method for solving the core pulling problem mainly comprises the following steps:

1. a split core: as shown in figure 1, a loose core is divided into a plurality of strip blocks, an inner strip block 4 and a peripheral strip block 3 are arranged, the strip blocks are connected with each other through dovetail grooves, the loose core is combined by the inner strip block and the peripheral strip block 3 before wax pressing and is placed in a mold, the strip blocks are drawn out one by one after the wax pressing, the inner strip block 4 is drawn out first, then the peripheral strip block 3 is drawn out, a mold shell 1 is opened, and then a wax mold 2 is taken out. The mode can lead to the wax pressing efficiency greatly reduced, and can form the joint line between the loose core, influence inner chamber surface quality.

2. Water soluble core: the inner cavity is first made with water soluble matter, such as urea, polyglycol and water soluble wax, and the wax mold is then pressed into mold and finally molten in water to form cavity.

3. Wax mould bonding: dividing a wax mould into two bodies, manufacturing two moulds, extruding the wax mould, and welding the wax moulds together to form an internal cavity. And so on.

The above core-pulling methods all have respective disadvantages, such as: the split core efficiency is too low, a mold closing line can be formed at the core-pulling splicing part, and a large flash can be formed after aging for a long time; the water soluble core has high cost and low efficiency; the wax mould stick welding also improves the cost, reduces the efficiency, and the bad quality of stick welding has great influence on the casting quality.

Disclosure of Invention

In order to overcome the defects of the existing core-pulling technology, the invention provides a novel core-pulling method for an investment precision casting wax pattern back-off inner cavity, and solves the problems of high cost, low production efficiency and poor quality.

The technical scheme is that the core pulling method for the wax mold back-off inner cavity of investment precision casting is characterized in that firstly, a movable sleeve type core pulling is manufactured according to the shape of the wax mold back-off inner cavity; the movable sleeve type core pulling device is characterized in that the movable sleeve type core pulling device consists of a hard inner core and an elastic outer sleeve sleeved on the hard inner core; the hard inner core is cylindrical, and the diameter of the cylinder is the same as the diameter of the small opening of the wax mould; the shape of the elastic outer sleeve is the same as that of the back-off part at the periphery of the diameter of the cylinder; before wax injection, the elastic outer sleeve is arranged on the metal inner core and then is placed into a mould shell, and wax injection is carried out according to the traditional method; after wax injection and shaping, the hard inner core is firstly drawn out, and the elastic outer sleeve becomes an empty shell which is easy to deform and contract after losing the support of the inner core, so that the elastic outer sleeve can be conveniently taken out from the small opening of the wax mould, and the inverted-buckled inner cavity structure of the wax mould is obtained.

The elastic jacket is made of rubber materials, and the melting temperature of the elastic jacket is more than 20 ℃ higher than that of the injected wax, so that the elastic jacket keeps certain hardness during the injection of the molten wax and prevents thermal deformation.

Further, the hard inner core is preferably a metal inner core.

Furthermore, in order to smoothly extract the hard inner core, a lubricant is coated on the contact surface of the hard inner core and the elastic outer sleeve.

The invention has the advantages that: 1. when in use, the elastic outer sleeve is arranged on the hard inner core to form the core pulling, the assembly is simple and convenient, and the elastic outer sleeve is elastic, so that the elastic outer sleeve is easy to deform and convenient to take out, and the production efficiency is greatly improved; 2. the elastic outer sleeve can be recycled, so that the cost is saved; 3. the elastic outer sleeve is provided with a smooth integral surface, so that a joint line cannot be formed in the inner cavity of the wax mould, and the product quality is improved.

Drawings

FIG. 1 is a schematic cross-sectional view of a conventional wax pattern and a split core;

fig. 2 is a schematic cross-sectional view of a wax pattern and a rubber sleeve type core pulling according to an embodiment of the present invention.

The illustration shows 1-die set, 2-wax die, 3-peripheral bar 3, 4-inner bar, 5-elastic outer sheath, 6-hard inner core, 7-lubricant.

Detailed Description

As shown in fig. 2, a core-pulling method for investment precision casting of a wax pattern undercut cavity includes firstly, manufacturing a movable sleeve type core-pulling according to the shape of the wax pattern undercut cavity; the movable sleeve type core pulling device comprises a hard inner core 6 and an elastic outer sleeve 5 sleeved on the hard inner core 6; the hard inner core 6 is in a cylindrical shape, and the diameter of the cylinder is the same as that of the small opening of the wax mould 2; the shape of the elastic outer sleeve 5 is the same as that of the inverted part at the periphery of the diameter of the cylinder; before wax injection, the elastic outer sleeve 5 is arranged on the metal inner core 6 and then is placed into the die shell 2, and wax injection is carried out according to the traditional method; after wax injection and shaping, the hard inner core 6 is firstly drawn out, and the elastic outer sleeve 5 becomes an empty shell which is easy to deform and shrink after losing the support of the inner core, so that the wax mold 2 can be conveniently taken out from a small opening of the wax mold 2, and the inverted inner cavity structure of the wax mold 2 is obtained.

The elastic jacket 5 is made of rubber materials, and the melting temperature of the elastic jacket is more than 20 ℃ higher than that of the injected wax, so that the elastic jacket keeps certain hardness during the injection of the molten wax, and the thermal deformation is prevented.

Furthermore, the hard inner core 6 is a selected metal inner core.

Further, in order to smoothly draw out the hard core 6, a lubricant 7 is applied to a contact surface between the hard core 6 and the elastic sheath 5.

Claims

1. A core-pulling method for an investment precision casting wax mold back-off inner cavity is characterized in that: firstly, manufacturing a movable sleeve type core pulling according to the shape of an inverted buckling inner cavity of a wax mould; the movable sleeve type core pulling device is characterized in that the movable sleeve type core pulling device consists of a hard inner core and an elastic outer sleeve sleeved on the hard inner core; the hard inner core is cylindrical, and the diameter of the cylinder is the same as the diameter of the small opening of the wax mould; the shape of the elastic outer sleeve is the same as that of the back-off part at the periphery of the diameter of the cylinder; before wax injection, the elastic outer sleeve is arranged on the metal inner core and then is placed into a mould shell, and wax injection is carried out according to the traditional method; after wax injection and shaping, the hard inner core is firstly drawn out, and the elastic outer sleeve becomes an empty shell which is easy to deform and contract after losing the support of the inner core, so that the elastic outer sleeve can be conveniently taken out from the small opening of the wax mould, and the inverted-buckled inner cavity structure of the wax mould is obtained.

2. The method of claim 1, wherein: the elastic jacket is made of rubber materials, and the melting temperature of the elastic jacket is more than 20 ℃ higher than that of the injection wax.

3. The method of claim 1, wherein: the hard inner core is preferably a metal inner core.

4. The method of claim 1, wherein: and a lubricant is coated on the contact surface of the hard inner core and the elastic outer sleeve.