Door for laser engraving device

A powered mechanism to open and close a door to a housing for a laser engraving device, with an arrangement that allows the powered mechanism to separate from the door so that the powered mechanism does not exert any force on any obstacle that the door may encounter when closing.

BACKGROUND

The present invention relates to an automatic door for an enclosure for a laser engraving device.

Many automatic doors for laser engraving device enclosures are very complicated and require sophisticated safety mechanisms to prevent the door from crushing anything that might become caught beneath the door when it is closing, such as a person's hand.

SUMMARY

An embodiment of the present invention provides a powered door closing mechanism which automatically separates from the door if an obstacle is encountered during the closing operation. This prevents the powered door closing mechanism from exerting force on the obstacle.

DESCRIPTION

FIGS. 1 and 2show a laser engraving device10having an automatic door14, a manual door16, and a base18. The enclosure12of the laser engraving device10is secured to the base18and encloses the laser (not shown). The automatic door14may be raised and lowered relative to the base18on which it is mounted, and the manual door16may be raised and lowered relative to the automatic door14, to which it is mounted. The automatic door14is raised and lowered by means of a powered linear actuator34, which, in this embodiment, is a piston/cylinder arrangement (SeeFIG. 3), as explained in more detail later. Other powered linear actuators are known and could be used instead of the piston/cylinder arrangement, if desired.

The manual door16includes a window20, to allow viewing of the inside of the enclosure12when the manual door16is closed, and a handle22to enable the user to manually raise and lower the manual door16relative to the automatic door14by guiding the manual door16along left and right parallel tracks24at the front edge of the automatic door14. The tracks24are mounted onto the front edge of the automatic door14and, in this embodiment, the tracks24and the front edge of the automatic door14are tilted at an acute angle β relative to the base18. To raise the manual door16, the user grabs the handle22with his hand and raises the manual door16against the force of gravity, which is acting to lower the door16. If desired, the manual door16may have spring reels to assist in opening, which would make the manual door16function as being very light weight.

There is a rubber seal on the bottom edges of the automatic door14and the manual door16to ensure that no laser light escapes the closed enclosure12along the bottom edge of the doors14,16when they are in the fully closed position.

To close the manual door16, the user may hold the handle22and push downwardly to control the rate at which the manual door16travels downwardly relative to the automatic door14, guided by the tracks24. In the event that an obstacle blocks the manual door16as it is being lowered, the user simply releases the handle22, and the door16will stop.

Since the manual door16is relatively lightweight, it will put very little force on the obstacle. The obstacle can then be removed, and the manual door16can be guided manually downwardly until it reaches the base18(if the automatic door14is closed) or until it reaches a stop at the lower edge of the track24(if the automatic door14is open). In this embodiment, there are rollers17(shown in Phantom inFIG. 1) mounted adjacent to the inner surface and rear edge of the manual door by means of pins19that extend through the door16and provide an axis for rotation for their respective rollers17. These rollers17rotate about their pins19as they roll along their respective track24on the front edge of the automatic door14as the manual door16is raised and lowered relative to the automatic door14.

Referring now toFIG. 2, the automatic door14may be raised and lowered relative to the base18(and relative to the enclosure12). The automatic door14rides up and down along left and right parallel guide rails26(See alsoFIGS. 7 and 8) mounted onto the enclosure12. Bearings28are used to facilitate the rolling of the automatic door14up and down along the guide rails26. A door housing attachment bracket30(SeeFIGS. 3-8) is bolted onto the automatic door14near the top. A door housing guide bracket32projects laterally from the attachment bracket30, and is secured to the attachment bracket30. The guide bracket32defines an opening39.

Referring now toFIGS. 3-6, a powered linear actuator, which, in this case, is a piston/cylinder arrangement, with a pneumatic cylinder34and a piston rod36, is used to open and close the automatic door14. The cylinder34is mounted in a fixed position relative to the base18, and the piston rod36travels up and down relative to the cylinder34. The piston/cylinder arrangement is user-actuated by pressing a button40(SeeFIG. 2) on the front of the base18. The cylinder34may be operated pneumatically or hydraulically, or the rod36may be mounted on a screw-type electrically-operated linear actuator, or other linear actuator.

The first end of the rod36is inside the cylinder34, and the free end38of the rod36has a small diameter tip38A, which extends through the opening39in the guide bracket32, and a larger diameter base38B, which is larger in diameter than the opening39, and which abuts the bottom of the guide bracket32.

As the rod36moves upwardly, the base38B at the free end38of the rod36pushes up against the bottom surface of the guide bracket32, lifting the automatic door14. It should be noted that the free end38of the rod36is not attached to the guide bracket32. The small diameter tip38A is received in the opening39, and the larger diameter base38B abuts and pushes up against the bottom of the guide bracket32as the rod36travels upwardly. The smaller diameter tip38A of the free end38of the rod36extends through the opening39(SeeFIG. 8) in the guide bracket32to help center the rod36on the guide bracket32, while the larger diameter base38B of the free end38abuts and pushes up against the bottom surface of the guide bracket32to lift the automatic door14.

To close the automatic door14, the user again presses the button40, which reverses the direction of travel of the rod36. The controller (not shown) ensures that the manual door16is lowered relative to the automatic door14before it will permit the rod36to begin travelling downwardly to close the automatic door14. The free end38of the rod36, travels downwardly with the rod36, and the automatic door14, which rests on the larger diameter base38B, falls downwardly due to the force of gravity, but it falls at a controlled rate, being supported by the free end38of the rod36. When the rod36is fully retracted, the automatic door14reaches its fully closed position shown inFIGS. 1, 3, and 4.

Should an obstacle21obstruct the automatic door14as the rod36is travelling downwardly, as shown inFIG. 5, the rod36continues to travel downwardly. Since the door14is stopped by the obstacle21, the rod36separates from the guide bracket32without pulling down on the automatic door14, as best shown inFIGS. 5 and 6. The automatic door14remains at the elevation where it was stopped by the obstruction, while the rod36continues to travel downwardly, separating the free end38of the rod36from the guide bracket32, so that the powered rod36does not exert any force on the obstacle21.

Since the powered rod36only supports the weight of the automatic door14and does not pull the door14downwardly, the powered rod36does not exert any downward force on the obstruction that might damage the door or the obstruction. Since the door14is lightweight, it does not exert enough force to harm a person's hand, arm, or other obstruction21.

When the obstruction21is removed, the automatic door14can be allowed to fall downwardly, guided in the left and right tracks26, until its bottom edge reaches the base18.

The controller for the laser engraving device10checks sensors (not shown) to ensure that the automatic door14and manual door16are in the fully closed position, with their bottom edges contacting the base18, before allowing the laser to be activated.

FIG. 1shows the manual door16in the fully open position relative to the automatic door14, and the automatic door16in the fully closed position.

FIG. 2shows the manual door16in the fully closed position relative to the automatic door14and the automatic door14in the fully open position.

It will be understood that the automatic door could be in the fully open position ofFIG. 2with the manual door16in the fully open position ofFIG. 1relative to the automatic door14, and the automatic door14could be in the fully closed position ofFIG. 1with the manual door16in the fully closed position ofFIG. 2relative to the automatic door14, as inFIG. 3. The controller checks to ensure that both the automatic door14and the manual door16are in the fully closed position before turning on the laser.

It will be obvious to those skilled in the art that modifications may be made to the embodiments described herein without departing from the scope of the present invention as claimed. For example, the manual door16could be eliminated, with the front and sides of the automatic door14being fixed together or made in a single piece, which would move as a single unit, to completely enclose the front opening of the enclosure12.