Pivot mechanism for furnace head

Abstract

In a dental furnace or dental press furnace comprising a furnace base (14) which is provided with a supporting surface for at least one dental restoration part, a furnace head (12) is provided which is connected to the furnace base (14) via a joint device (16) attached to the furnace base (14) and which is pivotable relative to the furnace base (14) via said device. Pivoting takes place about a pivot axis (40) which extends substantially parallel to the supporting surface, as well as a motor (42) which acts on the joint device (16) for the pivotable movement of the furnace head (12). The pivot axis (40) extends outside of the furnace head (12) and outside of the joint device (16).

Claims

1. Dental furnace or dental press furnace comprising a furnace base provided with a supporting surface for at least one dental restoration part, a furnace head connected to the furnace base via a joint device attached to the furnace base and wherein the furnace head is pivotable relative to the furnace base via said joint device, wherein pivoting takes place about a range of pivot axes which extend substantially parallel to the supporting surface, a motor which acts on the joint device for the pivotable movement of the furnace head, wherein the range of pivot axes extend outside of the furnace head and outside of the joint device, wherein the furnace head moves initially in an upward direction and subsequently pivots, wherein the furnace head is releasably connected to the joint device and the attachment of the furnace head to the joint device comprises pluggable molded parts, and wherein in or at the joint device a tension spring is received which acts against the weight of the furnace head and which serves to compensate for the weight of the furnace head.

2. Furnace according to claim 1, wherein the joint device comprises at least three legs which are connected to each other via joints and that between adjacent legs a first, a second, a third are formed.

3. Furnace according to claim 1, wherein the joint device comprises several legs, one of which is firmly connected to the furnace base, and to another one the furnace head is attached.

4. Furnace according to claim 1, wherein the joint device comprises several legs and wherein a head leg is connected to the furnace head and is formed as the leg facing the furnace head.

5. Furnace according to claim 1, wherein the joint device is provided with several legs which are connected to each other via joints and wherein a frame leg is fixed to the base and is connected via joints to two intermediate legs wherein first and second joint axes between the two intermediate legs are spaced apart from each other in a vertical direction, and wherein third and fourth joint axes of the two intermediate legs are connected to a fourth leg which is fixed to the furnace head.

6. Furnace according to claim 1, wherein the joint device is provided with two joint arrangements spaced apart from each other in a horizontal direction and spaced apart from each other in a direction parallel to the pivot axis and wherein the joint arrangements are each provided with several legs.

7. Furnace according to claim 6, wherein between the joint arrangements of the joint device the motor is received which is used to pivot the furnace head.

8. Furnace according to claim 7, characterized in that the tension spring comprises two individual tension springs which are received in the interior of the joint device between the arrangements of the joint device.

9. Furnace according to claim 1, wherein the joint device is provided with several legs which are connected to each other in the form of a convex square.

10. Furnace according to claim 1, wherein a molded part fixed to the furnace head has substantially the shape of a U turned upside down with side legs ending in angular faces.

11. Furnace according to claim 1, characterized in that a drive shaft of the motor is formed as a spindle and interacts with a worm gear which in turn drives the joint device.

12. Furnace according to claim 1, wherein the distance of the pivot axis to the furnace head is 0.1 to 2 times a largest length of the furnace head and/or the opening angle between the bottom of the furnace head and the top of the furnace base is 5 to 20 when the furnace head is open.

13. Furnace according to claim 1, wherein the joint device (16) comprises at least four legs which are connected to each other via joints and that between adjacent legs a first, a second, a third and a fourth joint axis are formed.

14. Furnace according to claim 1, wherein the joint device (16) comprises several legs, wherein a frame leg is firmly connected to the furnace base, and a head leg is connected to the furnace head.

Description

(1) Further advantages, details and features may be taken from the following description of several embodiments of the invention with respect to the drawings.

(2) FIG. 1 shows a schematic view of an inventive press furnace in one embodiment;

(3) FIG. 2 shows a schematic view of a detail of a conventional furnace illustrating the joint device;

(4) FIG. 3 shows a schematic illustration of a detail of an inventive furnace in a further embodiment, also illustrating the joint device;

(5) FIG. 4 shows an illustration of a further embodiment of an inventive furnace.

(6) The inventive furnace or press furnace 10 illustrated in FIG. 1 is formed as a press furnace in this embodiment. It is provided with a furnace head 12 and a furnace base 14 which are connected to each other via a joint device 16. The furnace head 12 comprises, in a way known, a firing chamber 18 which is intended for receiving a muffle 20.

(7) The joint device 16 is inventively formed in a special manner and comprises a frame leg 22 which is connected to the furnace base 14, a lower movable leg 24 and an upper movable leg 26. Both the legs 24 and 26 are each connected via joint axes 30 and 32 to the frame leg 22.

(8) The joint device 16 is further provided with a head leg 34 which is connected via joint axes 36 and 38 to the movable leg 24 or the movable leg 26. The head leg 34 is connected to the furnace head 12, and, in fact, in the illustrated first embodiment it is firmly connected.

(9) In the illustration according to FIG. 1 the open position as well as the closed position of the furnace head 12 are shown on top of each other.

(10) Using the inventive joint device 16, the furnace head 12 is pivotable about a virtual pivot axis 40 which lies considerably spaced apart from the furnace 10. By realizing this virtual pivot axis, a relatively small pivot angle of only about 18 is the result, even when the furnace head 12 is open.

(11) In the area of the joint device 16 a tension spring 41 is mounted. The tension spring preloads the head leg 34 to the top and serves to compensate for the weight of the furnace head so that a motor 42 with a comparatively low driving force by means of the driving shaft which is formed as a spindle and further by means of a worm gear which is connected thereto can open and close the furnace head 12.

(12) FIG. 2 schematically shows a joint device of a conventional furnace. Here as well as in the further figures, the same reference numbers designate the same parts. Here, the pivot axis 40 concurs with the joint axis 30, and the frame leg 22 is directly connected to the head leg 34 via the joint axis 30. A motor 42 is arranged laterally next to the joint device 16 and acts with a spindle onto the head leg 34.

(13) In contrast, FIG. 3 shows an inventive joint device 16. The illustration shows the closed position of the furnace head as a solid line and the open position as a dotted line. The embodiment of the joint device in the form of a convex square with the joint axes 30, 32, 36, 38 as corners of the square is clearly visible from FIG. 3. While the pivot axis 40 is presented only slightly outside of the furnace in the view according to FIG. 3, it is to be understood that the actual dimensioning rather corresponds to FIG. 1.

(14) The joint device 16 is shown in FIG. 1 and FIG. 3 in simple form.

(15) In a modified embodiment, the joint device 16 consists of two joint arrangements which are symmetric to each other and correlate each other. In front or behind the drawing layer, in addition to the joint arrangement illustrated, a further corresponding joint arrangement is shown so that both the joint arrangements which are spaced apart from each other in the direction of the pivot axis overall form the joint arrangement 16.

(16) Hereby, the movable legs 24 and 26 are provided preferably twice and the frame leg 22 has the shape of a U so that the center leg of the U extends vertically and the side legs of the U each receive both the joint axes 30 and 32.

(17) The same holds true for the head leg 34 which also connects both joint arrangements to each other and which has substantially the shape of a U in the horizontal section, too. Here, the joint axes 36 and 38 also extend into the side leg of the U. Between the frame legs 30, 32 the motor 42 is received so that altogether a very compact structure of the joint device 16 is achieved.

(18) FIG. 4 shows a further modified embodiment of an inventive furnace. Here, too, the head leg 34 extends substantially vertically when the furnace head 12 is closed. However, it is not directly connected to the furnace head 12. Rather, a molded part 50 is provided which is firmly connected to the furnace head 12 and has substantially the shape of a U turned upside down. Its side legs end in angular faces 52, 54 which form insertion slants relative to the head leg 34, and overlap it.

(19) For the locking between the head leg 34 and the molded part 50 a locking nose 56 is provided which is movably mounted at the molded part 50 and which passes through a corresponding opening in the head leg 34 in a locked position in order to, in this way, facilitate a secure connection between the head leg 34 and the furnace head 12.