Mold development example

The part Cross-piece

UPRZ LLC has a vast experience in the production of molds, for more than 20 years the company provides its own injection molding and performs many third-party orders. At tooling designing, plant experts are experimenting in search of new interesting and original solutions.

The product is meant to installation of sewerage systems. The material is polypropylene.

A feature of the product is the presence of circular undercuts in three mutually perpendicular pipe joints (two with a diameter of 110 mm and one with a diameter of 50 mm).

In addition, three mutually perpendicular pipe joints create numerous undercut zones on the outer surface of the part.

The construction of the mold

The dimensions of the mold are 490x530x479 (without protuberances). The forming cavity is located in the center of the part.

The central core gate is brought directly into the body of the molded product. Such a power system allows the melt to evenly flow around the rods.

Internal cavity of the product is formed by mold cores of a specially designed shape that allows to remove the mold cores from the undercuts of the part without the use of complex mechanisms. Hydraulic cylinders 97 are used to drive the inner mold cores and the bar 17. To remove the product from the mold core 27, the original design of the engineer A. Kovalev was used, which is used in other similar molds.

The outer part of the product is formed by matrices 12,13, bars 17,46,47,48,49. Four bars are additionally applied to form the elements of the outer surface of the part. All this determines the jointing planes perpendicular to each other and the complexity of the mold.

The work of the mold

• Molding cavity is filled with the polymer melt through the central gate runner (sprue bush 44). The mold is revealed after filling the mold, holding pressure and cooling process.
• During the opening of the mold, the wedges 35 put in motion the bar 46,47,48,49, releasing the pipe joint 50 mm. Then, the bar 17 and mold core 16 are put in motion, while mold cores 14,15 remain motionless due to undercutting in the product, they come into motion during trip of the bar 17 in 20 mm. The bar has released the product and the mold core F100 are removed from the part with the help of hydraulic cylinders releasing the undercut ring, as the material is still quite moldable. Then, hydraulic pusher of IMA moves forward the pushing system through the spars (the hydraulic pusher is connected to the shank, which pushes the plates with pushers forward to throw the part). In this case, through the rocking device 28.29, bearing 30 rotating on the axis remove the mold core 27 back, releasing the undercut ring of the pipe F50. The product is finally removed manually.
• When the mold is closed, the forming mold cores under the action of hydraulic cylinders enter the forming cavity, and the hydraulic ejector of the machine goes back. A new cycle begins.

The whole sequence of the molding process, removal of the part and the return of the mold elements to their original position should be clearly linked in time. Therefore, the mold can only be used on injection molding machines having a control system - a controller that allows you to program the sequence and response time of the working elements of the system.

Clean, to the smallest detail, knowledge of polymer processes allows us to calculate the molds of the most complex schemes and designs. Calculation and computer modeling is carried out at the most advanced level, using modern means.

UPRZ has advanced technical means for the production and testing of molds, including a fleet of machines: metal-working centers with CNC, modern injection molding machines and much more. In the production of complex matrices, the electroerosive processing method is used, burning high-precision complex surfaces in metal.

Molds made by UPRZ are distinguished by high operational characteristics, durability and maintainability. The correct selection of materials, high-quality steels, good heat treatment can extend the life of molds, and therefore bring more benefits to the customer.

Dzhangirov G.G.