JPH035290B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an undercut processing mechanism in a mold, and in particular, to a mechanism that holds an undercut pin against large injection pressure with a small driving force and is compact. The present invention relates to a mold undercut processing device that enables design.

(Prior Art) Hydraulic cylinders and slide cores have conventionally been used as undercut treatment devices for molds.

However, these devices are limited in their dimensional structure in terms of adjacent pitches when the undercuts are located close to each other in a narrow portion of the mold, or when the undercuts must be processed independently because the cutting directions are different.

In order to solve this problem, the movement of the hydraulic cylinder 51 shown in FIG. 4 has been changed in direction using a cam mechanism 52 or the like.

(Problems to be Solved by the Invention) However, in such conventional undercut processing devices, measures such as adding a cam mechanism are required, which increases the number of parts and increases the cost of the mold. was.

Furthermore, even in the case of single undercut treatment,
Because the hydraulic cylinder used as the drive source has a large outer diameter, it is necessary to make a large mounting hole in the insert, which is the center of the mold, which increases the processing time of the insert and reduces the strength of the insert. A problem arose that resulted in a decline.

Therefore, in order to solve the above problems, the present invention incorporates a toggle and cam mechanism into a hydraulic cylinder so as to withstand high injection pressure.
It is an object of the present invention to provide an undercut processing device which moves an undercut pin forward and backward with low input oil pressure or air pressure and which can downsize the cylinder.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides one of the toggle links constituting the toggle mechanism on the tip side of the fixed rod provided in the cylinder device fixed to the mold. At the same time, the other toggle link is attached to a shaft that moves the undercut pin provided in the mold forward and backward, and a piston that can freely engage with the toggle link is slidably installed in the cylinder device. It is characterized by what it did.

(Function) Since the present invention has the above configuration, when hydraulic pressure or compressed air is sent into the space defined by the fixed rod and the piston outer cylinder in the cylinder device fixed to the mold, the fixed cylinder is moved. In contrast, the piston outer cylinder moves forward.

As a result, the cam inside the piston outer cylinder presses the toggle mechanism in the direction to open it, thereby advancing the shaft connected to the toggle mechanism. As the shaft moves forward, the undercut pin is pressed and moved into position.
An undercut is formed within the mold.

In this state, even if high injection pressure is applied inside the mold, the undercut pin will not be pushed back due to the force-increasing action of the toggle mechanism, and the low-pressure driving source can sufficiently resist the injection pressure. .

Further, in contrast to the above action, when hydraulic pressure or compressed air is fed to move the piston outer cylinder backward with respect to the fixed rod, the toggle mechanism is moved in the closing direction by the cam of the piston outer cylinder. Therefore, the undercut portion retreats via the shaft, allowing the molded product to be removed. In this case, it is sufficient to overcome the pulling force from the molded product, but in this case as well, the undercut pin can be retreated with a small driving force using the toggle mechanism.

In this way, it is possible to operate the undercut using a cylinder with low pressure and low driving force.

Therefore, the hydraulic cylinder itself can be miniaturized without providing any special external equipment other than the hydraulic cylinder, and the apparatus can perform undercut treatment in a narrow portion of an adjacent pitch.

(Example) Embodiments of the present invention will be described based on the drawings.

1 and 2, 1 is a hydraulic cylinder in the device of the present invention, and a fixed side 2a of the mold 2.
The flange portion 6 of the cylinder 5 is inserted into the mounting hole 4 formed coaxially with the undercut pin 3 inside.
A boss 7 protruding from the mold is inserted, and the flange portion 6 is fixed to the mold with two bolts 8, 8.

Inside this hydraulic cylinder 1, a fixed rod 9 is formed integrally with the cylinder 5 and protrudes from the rear end of the cylinder 5 (upper end side in the figure) along the central axis. Two port openings 10, 11 are provided for supplying hydraulic fluid into the cylinder 5.

The fixed rod 9 also has a large diameter portion 9a in its center.
A rotating shaft 12 is provided on the tip side thereof, and a toggle mechanism 17 in which toggle links 13 and 14 are connected by rotating shafts 15 and 16, respectively, is attached to this. The ring 14 of the toggle mechanism 17 is connected to the shaft 18 by a rotating shaft 16.
The shaft 18 is connected to the undercut pin 3 by a loose connection head 19 and a connection 20.

In the space between the fixed rod 9 and the cylinder 5, a piston outer cylinder 21 is provided as an outer cylinder of the fixed rod 9 and slides inside the cylinder 5.

The piston outer cylinder 21 is assembled and integrated from a plurality of blocks, and its outer periphery partially contacts the inner periphery of the cylinder 5, and furthermore, a dog 22 is formed in the center. This dog 22 is the piston outer cylinder 2.
Limit switch 2 for position detection by sliding 1
3 and 24 to determine their sliding stroke.

In addition, the inner circumference of the piston outer cylinder 21 and the fixed rod 9
A space defined by the outer circumference of the fixed rod 9 is provided, and this space serves as hydraulic chambers 25 and 26 separated by the large diameter portion 9a of the fixed rod 9. Furthermore, an extension portion 2 as a tip of the piston outer cylinder 21 is provided.
A roller 27 is coaxially provided outside the rotating shaft 15 inside the piston 1a, and cam grooves 28 and 29 for regulating the movement of the roller 27 are formed eccentrically on the inner periphery of the piston outer cylinder 21.

Here, 30, 31, 32 are O-rings for hydraulic seals, 33, 34, 35 are escape holes for compressed air accompanying the movement of each piston, and 36 is a keyway for preventing rotation of the undercut pin 5. It is a 37 detent pin.

Next, the operation of the undercut processing apparatus of the present invention will be explained.

In the state shown in FIG. 1, when hydraulic pressure is supplied to the hydraulic pressure supply port 10, hydraulic oil enters the hydraulic chamber 26 through the oil hole 41. As a result, the piston outer cylinder 21 is pushed out in the direction of arrow P in the figure. Since the cam groove 28 in the extension portion 21a moves together with the piston outer cylinder 21, the roller 27 provided in the toggle mechanism 17 is pushed diagonally downward to the right in the figure, and the toggle mechanism 17 begins to open.

As the toggle mechanism 17 expands, the shaft 18 moves in the direction of arrow Q, pushing out the undercut pin 3.

Therefore, when the piston outer cylinder 21 of the hydraulic cylinder 1 reaches the bottom dead center, that is, as shown in FIG. 2, the tip 3a of the undercut pin 3 protrudes and stops. At this time, since the dog 22 pushes down the limit switch 24, it can be confirmed that the tip end 3a of the pin 3 is protruding, and a signal is issued to fill the molding material into the core part 38 of the mold to perform molding. Once the molding material has solidified and is ready to be removed from the mold, the hydraulic pressure is applied to port 1.
1 and sent into the hydraulic chamber 25 through the hydraulic pressure supply hole 42. As a result, the piston outer cylinder 21
is moved in the direction of arrow R in the figure. At this time, the cam groove 29 in the extension part 21a together with the piston outer cylinder 21
Since the toggle mechanism 17 also moves, a roller 27 is provided in the toggle mechanism 17 to push the roller 27 diagonally upward to the left in the figure.
begins to close.

When the toggle mechanism 17 closes, the shaft 18 moves in the direction of arrow S and the undercut pin 3
returns to its original position, opens the moving side 2b of the mold,
The molded article 38 can be taken out.

In this embodiment, the cylinder is driven by hydraulic pressure, but the cylinder is not limited to this, and other methods such as pneumatic pressure may be used. When a pneumatic cylinder is used, there is no need for oil leakage or air bleeding every time the mold is installed, and the time required to install the mold to the molding machine can be significantly shortened.

Furthermore, as shown in Fig. 5 (conventional example) and Fig. 6 (this embodiment), when the compact toggle mechanism of the present invention is incorporated, the outer diameter width D ₂ of the device using a hydraulic cylinder etc. is smaller than that of the conventional example. Since it is extremely small compared to the outer diameter width D ₁ of , the adjacent pitch P ₂ can also be made smaller compared to P ₁ .

(Effects of the Invention) As is clear from the above explanation, the present invention opens and closes a toggle mechanism built in a piston outer cylinder that can be moved by low-pressure driving force, and applies that force to the undercut portion. , even if high injection pressure is applied to the mold, it can withstand the force sufficiently.

Therefore, the cylinder itself can be downsized, low-pressure driving force can be used, and adjacent pitches in undercutting in different directions can be made smaller, improving the degree of freedom in designing the molded product.

In addition, since the toggle cam mechanism is built-in, there is no need to add any other external equipment, so there is no need for troublesome processing on the mold, which shortens the mold production period and reduces costs. Moreover, the strength and rigidity of the mold can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing the top dead center state of a hydraulic cylinder in a device that is an embodiment of the present invention;
The figure is a longitudinal sectional view showing the bottom dead center state of the hydraulic cylinder in Figure 1, Figure 3 is a perspective view of the hydraulic piston rod with toggle of the device in Figure 1, and Figure 4 is a diagram showing the hydraulic cylinder using the conventional hydraulic cylinder. An explanatory diagram when performing undercut processing, FIG. 5 is a diagram showing the limit of adjacent pitch in the conventional device, and FIG. 6 is a diagram showing the improved limit of adjacent pitch in the device of the present embodiment. . DESCRIPTION OF SYMBOLS 1... Hydraulic cylinder, 2... Mold, 3... Undercut pin, 9... Fixed rod, 18... Shaft, 21... Piston outer cylinder.

Claims (1)

[Scope of Claims] 1. One of the toggle links constituting the toggle mechanism is attached to the tip side of a fixed rod provided in a cylinder device fixed to the mold, and the other toggle link is installed in the mold. An undercut processing device for a mold, characterized in that the provided undercut pin is attached to a shaft that moves forward and backward, and further, a piston that can freely engage with the toggle link is slidably housed in the cylinder device.