Patent Description:
Die casting is a molding process that can produce a formed part in many different ways, such as, for example, low pressure die casting, high pressure die casting, and high integrity die casting. Die casting typically involves closing two halves of a mold to enclose a mold cavity into which a molten casting material is introduced. The casting material flows into and fills the mold cavity and then is allowed to cool and solidify into the desired part. After an appropriate cooling time, the mold is opened and the formed part can be removed.

Low pressure die casting uses lower injection pressures to produce high dimensionally accurate parts with minimal internal porosity. This process involves introducing a molten alloy into a mold-typically a mold held in a vertical orientation-under low velocity and pressure to minimize turbulence and trapped air to produce a high-density part. Process cycle times for low pressure die casting are long (e.g., <NUM>-<NUM> minutes) to allow for cooling of the part. The wall thickness of the formed part is typically greater than <NUM> millimeters, resulting in a heavy cast part. The initial capital investments are lower for low pressure die casting when compared to high pressure die casting.

High pressure die casting uses a high injection pressure in the molten casting media so that molds can be used to produce a thinner walled part at a greater speed than low pressure casting. The high pressure and high speed of the molten alloy injection is needed to ensure that the mold cavity is filled entirely by the molten material. The wall thickness of the parts formed by this process can be about <NUM> millimeter to about <NUM> millimeters. By virtue of the thinner wall thickness, the process cycle times are lower for high pressure die casting than low pressure die casting. The size of parts formed by high pressure die casting is limited by the pressure that can be applied over the mold cavity by the die press; that is, a part cannot be formed in a press when the injection pressure applied to the area of the mold cavity would result in a force that is greater than the closing force applied to the mold to maintain the mold in the closed condition. If the maximum closing force of the die press is exceeded by the pressure of the molten casting media, the mold halves can be spread apart at the parting line (the border of the mold cavity) that can allow molten metal to "spit" out of the mold. The "spitting" molten metal not only results in non-conforming molded parts but tends to be very dangerous. <CIT> and <CIT> disclose a die casting press comprising a die locking system attached to the fixed die and the movable die.

The claimed die casting press is according to annexed independent claim <NUM>. Other advantageous features are defined in the dependent claims.

The claimed die locking system is according to annexed independent claim <NUM>. Other advantageous features are defined in the dependent claims.

The claimed method of die casting is according to annexed independent claim <NUM>. Other advantageous features are defined in the dependent claims.

To further clarify various aspects of embodiments of the present disclosure, a more particular description of the certain embodiments will be made by reference to various aspects of the appended drawings.

Embodiments and other features and advantages of the present disclosure will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:.

The following description refers to the accompanying drawings, which illustrate specific embodiments of the present disclosure.

Exemplary embodiments of the present disclosure are directed to devices and methods for locking or clamping the multiple pieces of a casting die-e.g., male and female die halves-together. It should be noted that various embodiments of die locking systems are disclosed herein, and any combination of these options can be made unless specifically excluded. In other words, individual components of the disclosed devices and systems can be combined unless mutually exclusive or otherwise physically impossible.

As described herein, when one or more components are described as being connected, joined, affixed, coupled, attached, or otherwise interconnected, such interconnection may be direct as between the components or may be indirect such as through the use of one or more intermediary components. Also as described herein, reference to a "member," "component," or "portion" shall not be limited to a single structural member, component, or element but can include an assembly of components, members, or elements. Also as described herein, the terms "substantially" and "about" are defined as at least close to (and includes) a given value or state (preferably within <NUM>% of, more preferably within <NUM>% of, and most preferably within <NUM>% of).

The present disclosure relates to die cast molding and, in particular, high pressure/high integrity die cast molding with, for example, molten aluminum or magnesium. The high pressure/high integrity die cast molding uses a die formed from two mold halves that are held together under high pressure under the injection of the molten metal. The molds or dies formed for high pressure and high integrity die casting are typically designed with a flat parting line-i.e., the portion of the mold at the perimeter of the mold cavity where the two mold halves or dies meet-to ensure a that the mold cavity is sufficiently sealed to prevent leakage of the molten casting media that can leak from the mold cavity and result in flashing along the parting line that must be removed after casting and/or spitting of molten media from the mold or die. An exemplary die casting system described herein includes a supplemental clamping or locking system that is incorporated into the die or die press to supply additional locking support in the closed condition of the mold during the die cast injection process. The additional locking or clamping force provided by the supplemental clamping or locking system reduces the likelihood of leakage at the parting line leading to flashing on the finished part or spitting during casting.

The molds or dies used in high pressure and high integrity die casting are sized according to the press that will be used to make the castings. In particular, the size of the die or mold is limited by the projected maximum footprint of the machine platens that the dies or molds attach to. The projected size of the casting is similarly limited. If a portion of the die or mold were to project outside of the platen surface, the injection pressure can exceed the clamping or closing pressure of the die so that the casting media leaks out and results in die cast parts with flashing along the parting line or that are otherwise non-conforming because of the loss of casting media at the parting line where the mold or die extended beyond the platen. Consequently, molds or dies for parts that are larger than the die press platens are not possible without the use of a larger machine. Larger machines may have long lead times and therefore might not be readily available for purchase and can also be cost prohibitive. The exemplary supplemental die clamping or locking system described herein enables larger molds to be used in a die casting system, thereby expanding the capabilities of existing die casting machines.

Existing die casting machines can be modified to incorporate the exemplary supplemental die locking or clamping systems described herein. Dies for die casting machines can also be created with the exemplary supplemental locking systems built-in or with features that facilitate the easy attachment of the exemplary systems described herein.

An exemplary die casting machine includes a stationary mold half or cover and a moveable mold half or ejector that can be moved by a suitable actuator to close against the stationary mold half or cover. An exemplary die locking system includes a locking post or pin attached to one mold or die half and a locking cam secured to the opposite mold or die half. The die locking system-i.e., the locking posts or pins, the locking cams, and actuators for actuating the locking cams-can be removably attached to the dies or molds such that the same die locking system can be used across a wide variety of dies or molds. The attachment of the locking posts or pins, the locking cams, and actuators can be attached to a die or mold half via a quick-change system to facilitate easy removal and replacement of these components. While the exemplary die locking systems disclosed herein can be used on a wide variety of molds or dies, the components of the die locking system can also be sized for a particular mold or die based on the mold or die size and the supplemental forces required.

When the die halves are closed together, the locking cam is actuated to engage the locking post or pin, thereby mechanically locking the two die halves together. The engagement surfaces of the locking post or pin and the locking cam can include a slope so that force applied to the locking cam is transformed into additional closing force via the locking post or pin. When the die locking system is locked, the pressure of the hydraulic actuator used to actuate the locking cams can be monitored to calculate the supplemental locking force transferred through the locking cams to the locking posts or pins. Thus, a control system for the die press and die locking system can measure and control the supplemental locking forces being applied to the die or mold halves via the die locking system. The control system can also consider the required clamping and locking forces and can prohibit operation of the die press if insufficient locking force is available from the installed die locking system-i.e., the control system can check whether a properly sized die locking system has been installed for the desired casting pressure and mold or die size.

Referring now to <FIG>, an exemplary die press <NUM> that includes an exemplary die locking system <NUM> is shown. The die press <NUM> includes a fixed or stationary platen <NUM> and a moveable platen <NUM>. A fixed or stationary die <NUM> is attached to the fixed platen <NUM> and a moveable die <NUM> is attached to the moveable platen <NUM>. As is well known in the art, the fixed or stationary die <NUM> can also be described as a cover and the moveable die <NUM> can also be described as an ejector. The moveable platen <NUM> is moved towards and away from the fixed platen <NUM> by a main actuator (not shown) to close and open the moveable die <NUM> and to provide a clamping or closing force between the moveable die <NUM> and the fixed die <NUM> in the closed condition. In the closed condition, the fixed die <NUM> and the movable die <NUM> enclose a mold cavity <NUM> (<FIG>). The main actuator used to move the movable platen <NUM> can be any suitable actuator or plurality of actuators, such as, for example, a hydraulic actuator, a mechanical actuator, an electromagnetic actuator, or the like. As is described above, the maximum clamping or closing force applied by the main actuator is typically used in the industry to differentiate one die press from another-e.g., a <NUM> ton die press and a <NUM>,<NUM> ton die press.

During a die casting operation, pressurized molten casting media, such as, for example, molten aluminum or molten magnesium, is injected into and fills the mold cavity <NUM> at an injection pressure to form the desired die cast part. A parting line <NUM> (<FIG>) is formed at the perimeter of the mold cavity <NUM> where the fixed die <NUM> and the moveable die <NUM> meet. Clamping pressure from the main actuator and the die locking system <NUM> prohibits leakage of casting media from the mold cavity <NUM> at the parting line <NUM> when the moveable die <NUM> is closed against the fixed die <NUM>.

The moveable platen <NUM> is moved by the main actuator toward and away from the fixed or stationary platen <NUM> along a plurality of tie bars <NUM>. The main actuator applies a force between a portion of the tie bars <NUM> and the moveable platen <NUM> to cause the moveable platen <NUM> to move along the tie bars <NUM> until the moveable die <NUM> closes against the fixed die <NUM>. The fixed die <NUM> and the moveable die <NUM> are supported by a bottom frame (not shown) that supports and aligns the fixed die <NUM> and the moveable die <NUM>. Guide pins in the fixed die <NUM> and the moveable die <NUM> maintain alignment between the fixed die <NUM> and the moveable die <NUM> when the die press <NUM> is closed. During casting, the main actuator closes the moveable die <NUM> against the fixed die <NUM> and applies pressure to the moveable die <NUM> to ensure that the moveable die <NUM> and fixed die <NUM> do not separate when the mold cavity <NUM> is filled with pressurized molten casting media. An exemplary die locking system <NUM> can be included in the fixed die <NUM> and the moveable die <NUM> to provide a supplemental locking force that helps the main actuator hold the moveable die <NUM> against the fixed die <NUM> during casting. In this way, the die locking system <NUM> can increase the maximum closing force or capacity of the die press <NUM>.

The die locking system <NUM> includes a locking pin <NUM> attached to the fixed die <NUM> and a locking cam <NUM> attached to the moveable die <NUM>. T-shaped slots <NUM> in the fixed die <NUM> receive and retain the locking pins <NUM>. When the moveable die <NUM> is closed against the fixed die <NUM>, the locking pins <NUM> extend through holes <NUM> of the moveable die <NUM> where the locking pins <NUM> are engaged by the locking cams <NUM>. The locking pins <NUM> can be removably attached to the fixed die <NUM> via the slots <NUM> or can be attached permanently to the fixed die <NUM> via welding or by being integrally formed with the fixed die <NUM>. The locking cams <NUM> extend through actuator openings <NUM> in the sides of the moveable die <NUM> and are moved in and out of engagement with the locking pins <NUM> by hydraulic actuators <NUM> that are attached to the sides of the moveable die <NUM>.

The die locking system <NUM> can be added to any suitable die casting system by machining the slots <NUM> into the fixed die <NUM> and the holes <NUM> and openings <NUM> in the moveable die <NUM>. The opposite can also be done, with the slots <NUM> being formed in the moveable die <NUM> and the holes <NUM> and openings <NUM> being formed in the fixed die <NUM>. A mixture of both arrangements is also possible, with corresponding slots <NUM>, holes <NUM>, and openings <NUM> being formed in both the fixed die <NUM> and the moveable die <NUM>.

Referring now to <FIG>, the die locking system <NUM> is shown separate from the die press <NUM> in a locked or closed condition (<FIG>) and an unlocked or open condition (<FIG>). The die locking system <NUM> includes the locking post or pin <NUM> that includes a flange <NUM> for engaging the corresponding slot <NUM> of the fixed die <NUM>. Locking grooves or notches <NUM> in the locking post or pin <NUM> are shaped to engage with the locking cam <NUM>. The locking cam <NUM> includes fingers or protrusions <NUM> spaced apart by a gap <NUM>, the protrusions <NUM> being shaped to engage the locking grooves <NUM> of the locking post <NUM>. An inclined surface <NUM> of the locking groove <NUM> corresponds to an inclined surface or ramp <NUM> of the protrusions <NUM>. The locking cam <NUM> is moved from an unlocked or open condition (<FIG> and <FIG>) into engagement with the locking post <NUM> in a locked or closed condition (<FIG> and <FIG>) by the actuator <NUM> that includes a shaft <NUM> for attaching the locking cam <NUM> to the actuator <NUM>.

Referring now to <FIG>, a section of the die press <NUM> including one die locking system <NUM> is shown to illustrate the steps of closing the die press <NUM> and locking the die locking system <NUM>. When the die is in the open condition (<FIG>), the locking cam <NUM> is also moved into the unlocked or open condition (<FIG>) to prepare for closing the moveable die <NUM> against the fixed die <NUM>. In the closed condition (<FIG>) the locking cam <NUM> is moved from the open or unlocked condition (<FIG>) to the closed or locked condition (<FIG>) by the actuator <NUM> extending the actuator shaft <NUM>.

Referring now to <FIG> and <FIG>, the exemplary die press <NUM> is shown with a fixed die <NUM> and a moveable die <NUM>. The fixed or stationary die <NUM> is attached to the fixed platen <NUM> and the moveable die <NUM> is attached to the moveable platen <NUM>. The moveable platen <NUM> is moved towards and away from the fixed platen <NUM> by a main actuator (not shown) to close and open the moveable die <NUM> and to provide a clamping or closing force between the moveable die <NUM> and the fixed die <NUM> in the closed condition. In the closed condition, the fixed die <NUM> and the movable die <NUM> enclose a mold cavity (half of which is visible in <FIG>). The main actuator used to move the movable platen <NUM> can be any suitable actuator or plurality of actuators, such as, for example, a hydraulic actuator, a mechanical actuator, an electromagnetic actuator, or the like.

The fixed die <NUM> and the moveable die <NUM> include corresponding ends <NUM>, <NUM> that extend beyond the projected area of the fixed and moveable platens <NUM>, <NUM>. The clamping or closing force of the main actuator is applied to the fixed die <NUM> and the movable die <NUM> within the projected area of the fixed platen <NUM> and the moveable platen <NUM>. As the ends <NUM>, <NUM> of the fixed and moveable dies <NUM>, <NUM> extend further from the projected area of the fixed and moveable platens <NUM>, <NUM> the likelihood of the parting line will separate when subjected to casting pressures increase. The ends <NUM>, <NUM> of the fixed and moveable dies <NUM>, <NUM> can be pressed together by the die locking systems described herein, such as, for example, the die locking system <NUM> described above to reduce the likelihood of separation at the parting line at the ends <NUM>, <NUM>.

During a die casting operation, pressurized molten casting media, such as, for example, molten aluminum or molten magnesium, is injected into and fills the mold cavity <NUM> at an injection pressure to form the desired die cast part. A parting line <NUM> is formed at the perimeter of the mold cavity <NUM> where the fixed die <NUM> and the moveable die <NUM> meet. The die locking system <NUM> can be attached to the ends <NUM>, <NUM> of the fixed and moveable dies <NUM>, <NUM> to provide additional clamping or closing force so that the entirety of the fixed and moveable dies <NUM>, <NUM> are pressed together with sufficient force to resist the injection pressure of the molten casting media. Clamping pressure from the main actuator and the die locking system <NUM> prohibits leakage of casting media from the mold cavity <NUM> at the parting line <NUM> when the moveable die <NUM> is closed against the fixed die <NUM>. Thus, the maximum effective clamping force of the die press <NUM>-i.e., the pressure that the die press is capable of applying across the entirety of the projected surface of the fixed and moveable dies-can be increased by the addition of the die locking system <NUM>.

Referring now to <FIG>, exemplary die locking systems <NUM>, <NUM> are shown with different configurations for the locking cam than the die locking system <NUM> described above. Both of the die locking systems <NUM>, <NUM> are shown separate from the die press <NUM> and in a locked or closed condition (<FIG> and <FIG>) and in an unlocked or open condition (<FIG> and <FIG>).

Referring now to <FIG>, a die locking system <NUM> is shown that has a single locking cam for fitting in an opening of a locking post. The die locking system <NUM> can be used with any die and die press described herein. The die locking system <NUM> includes the locking post or pin <NUM> that can include a flange or other feature (not shown) for engaging a corresponding slot <NUM> of the fixed die <NUM>. A single opening slot <NUM> in the locking post or pin <NUM> is shaped to engage with a locking cam <NUM>. The locking cam <NUM> includes an inclined surface <NUM> shaped to engage a corresponding inclined surface (not shown) of the locking opening <NUM> of the locking post <NUM>. The locking cam <NUM> is moved from an unlocked or open condition (<FIG>) into engagement with the locking post <NUM> in a locked or closed condition (<FIG>) by the actuator <NUM> that includes a shaft <NUM> for attaching the locking cam <NUM> to the actuator <NUM>.

Referring now to <FIG>, a die locking system <NUM> is shown that operates via a pivoting movement. The die locking system <NUM> can be used with any die and die press described herein. The die locking system <NUM> includes the locking post or pin <NUM> that can include a flange or other feature (not shown) for engaging a corresponding slot <NUM> of the fixed die <NUM>. Locking grooves or notches <NUM> in the locking post or pin <NUM> are shaped to engage with the locking cam <NUM>. The locking cam <NUM> includes fingers or protrusions <NUM> spaced apart by a gap <NUM>, the protrusions <NUM> being shaped to engage the locking grooves <NUM> of the locking post <NUM>. An inclined surface <NUM> of the locking groove <NUM> corresponds to an inclined surface or ramp <NUM> of the protrusions <NUM>. The locking cam <NUM> is moved from an unlocked or open condition (<FIG>) into engagement with the locking post <NUM> in a locked or closed condition (<FIG>) by the actuator <NUM>. The locking cam <NUM> is attached to a pivoting linkage <NUM> that enables the locking cam <NUM> to pivot between the locked and unlocked condition. The actuator <NUM> includes a shaft <NUM> that is attached to the pivoting linkage <NUM> to facilitate pivoting the locking cam <NUM> between the locked and unlocked positions.

Claim 1:
A die locking system for a die press, the die locking system comprising:
a locking post (<NUM>, <NUM>, <NUM>);
a locking cam (<NUM>, <NUM>, <NUM>) comprising a sloped engagement surface for engaging a corresponding sloped engagement surface of the locking post; and
an actuator for moving the locking cam (<NUM>, <NUM>, <NUM>) between a locked position wherein the locking cam (<NUM>, <NUM>, <NUM>) engages the locking post (<NUM>, <NUM>, <NUM>) and an unlocked position wherein the locking cam (<NUM>, <NUM>, <NUM>) is disengaged from the locking post (<NUM>, <NUM>, <NUM>).