A China Auto Car Door Trim mould maker
The machine for which the alternate design of stripper type auto car door mould is shown in Figs. 55,56,57 is equipped with two adjustable ejector rods (detail 1) and no register provisions are made on the stripper mold half.
In this case the complete auto car door mould is first clamped in place to the stationary mold mounting plate of the machine clamping provision being the slot or groove (detail 8). The extended sprue bushing provides a register. The machine is then closed after alignment is made between machine ejector rods and clearance holes provided for them in the stripper base or core mounting plate. Next, the stripper mold half is clamped to the movable mounting plate of the machine clamping provision in this case being the slot or groove. The set-up is now complete except for the adjustment of the mold space between the platens of the machine.
The injection or cover half of this mold consists of the following parts:
cover binder ( or cavity insert back-up plate) made of alloy steel (detail 19); cavity insert retainer plate, also made of alloy steel (detail 7); cavity inserts, utilizing a suitable hobbing material (detail 16); sprue bushing with ball seat for abutment with the machine nozzle (detail 9); and guide pin bushings (detail 14).
The cavity insert back-up plate and the cavity insert retainer plate (details 19 and 7) are fastened together in the same manner as the corresponding plates on the ejector type mold.
The back-up plate (detail 19) is lathe machined and ground on the cavity inserts side to insure parallelism. The cavity insert retainer plate is lathe machined also, and ground on both sides with holes bored for cavity inserts. The gating is machined in this plate because the shot will be removed with the stripper mold half and there will be no problem of the gates sticking with the stripper plate shows part of a stripped shot or casting with the entire molded part flush with the surface of the stripper plate.
The stripper half of this mold consists of two alloy steel main plates and the following parts: stripper plate retainer bolts (detail 3); sprue sucker or stripper pin (detail 6); cavity cores (detail 13); stripper plate guide pin bushings (detail 12); and guide pins (detail 11).
The two main plates are the core or base plate and the stripper plate. The core plate is lathe machined and ground on the core fastening side. The stripper plate is also lathe machined, but ground on both sides.
The cavity insert retainer, stripper and core plates are now clamped together. Guide pin bushing and guide pin holes are bored first, cavity inserts and core holes next. The guide pins, which are in the stripper half of this auto car door mould, are to be press-fitted in the core plate (detail 10). Guide pin bushing (details 12 and 14) are press-fitted with stripper and cavity insert retainer plates (details 5 and 7) respectively. The cores are lathe machined，polished on plastics contacting surfaces, and ground to insure close tolerance with the bored holes in the stripper plate. A tapped hole provides the fastening between the base plate and cores by socket head screws (detail 2).
Stripper plate retainer bolts (detail 3) are incorporated because the stripper plate is not fastened to the core plate. It is evident that without these pins there would be a possibility of the plate coming off the guide pins and falling from the machine. The stripper plate is permitted to travel the distance space C
in Fig. 56 This distance should be slightly more than space E in Fig. 57 because if distance E were greater than distance C the machine ejector rods would either strip the threads or break the stripper bolts. Space D, Fig. 57, is the amount of distance the machine opens. Space D minus space E is the amount the machine opens before the ejector rods stop the stripper plate.
The sprue sucker or stripper pin (detail 6) is fastened to the stripper core plate as shown and is made in such a way that when the plastics material is injected into the auto car door mould it flows around the diamond shape designed to provide an undercut which will withdraw the plastics sprue from the sprue bushing as the mold opens. When the stripper plate is stopped by the machine ejector rods the sprue stripper pin will strip from the plastics material (detail 21) leaving it free to fall or be removed from the car door mould. Similar pins may be used to remove gating on car door mould where long or heavy gates are used.
It is evident that no ejector pin marks will appear on the parting line surface of the molded car door if it is molded in a stripper type mold. In many cases this is a definite requirement and in such cases the type of mold illustrated in Figs. 55, 56 and 57 should be used.
Another advantageous feature apparent in this type of mold is that no open space is required behind the cores for an ejector mechanism. This means the cores and retaining plates are backed up solidly by the movable press platen. With no ejector box opening, bending of the mold faces at the parting line is eliminated. In this way flashing due to auto car door mould making will be held to a minimum.