METHOD FOR MANUFACTURING A HYDRAULIC DAMPER AND HYDRAULIC DAMPER

Description

[0001] The invention relates to a method for producing a hydraulic damper and to a hydraulic damper. The hydraulic damper comprises a damper housing and a damper piston connected to a piston rod, which is accommodated in the damper housing. The damper piston has a piston body axially penetrated by at least one overflow hole through which damping fluid can flow during the damping process.

[0002] Such hydraulic dampers have been known for a long time and are used in a variety of technical fields. One such technical field is the furniture industry, where such hydraulic dampers are used to prevent hard impacts on movable furniture parts, such as flaps, drawers, etc., as they move between the open and closed positions.

[0003] Such hydraulic dampers used in the furniture industry are typically small in size to allow for space-saving installation on the associated furniture component. The relatively small size of such hydraulic dampers naturally also results in a relatively small damper piston. In particular, the overflow hole axially penetrating the piston body of the damper piston is relatively small, i.e., has a relatively small diameter.

[0004] The damping force of the hydraulic damper depends significantly on the diameter of the overflow hole. With overflow holes of such small diameters, often in the tenths of a millimeter range, it is difficult to maintain the required tolerances during manufacturing. The current state of the art is to create overflow holes in plastic piston bodies during the production of the piston bodies using plastic injection molding. Maintaining the required tolerances for overflow holes with diameters of only a few tenths of a millimeter is difficult, if not impossible, with plastic injection molding.

[0005] The document WO2018 / 153542A1 discloses a known hydraulic damper.

[0006] The object of the invention is therefore to provide a method for producing a hydraulic damper and a hydraulic damper with which hydraulic dampers with a specific damping force can be produced reliably without large amounts of waste.

[0007] The method according to the invention for producing a hydraulic damper is characterized in that the overflow hole is introduced by irradiating the piston body with a laser beam.

[0008] Overflow holes produced by laser machining are highly accurate, thus avoiding large tolerances such as those found in plastic injection molding. Laser machining can be achieved by laser cutting, laser cutting, or laser flame cutting.

[0009] In a further development of the invention, the piston body is a plastic component. In this case, the piston body is expediently manufactured by plastic injection molding, while the overflow hole is created using a laser beam. Laser cutting is also suitable for plastics.

[0010] According to the invention, the piston body has a piston rod channel in which the piston rod is received.

[0011] According to the invention, the piston rod channel is introduced by irradiating the piston body with a laser beam.

[0012] In a further development of the method according to the invention, the overflow hole is measured after its manufacture. In particular, the channel diameter of the overflow hole is measured. However, it is also conceivable to measure other geometric parameters of the overflow hole, for example, the length of the overflow hole or the roundness of the overflow hole.

[0013] In a further development of the method according to the invention, the damper piston is sorted into batches after the overflow hole has been measured depending on the measurement result. Sorting is preferably carried out according to the measured actual value of the hole diameter. Alternatively or additionally, if the measurement result deviates too greatly from a target value, in particular the actual value of the hole diameter, the overflow hole can be remachined, in particular by laser irradiation. It is possible, for example, to assign certain tolerances of the measurement result to the batches. For example, it is possible for all damper pistons whose measurement result from the measurement of the overflow hole has essentially no deviation from a target value to be sorted into one batch.For example, parts can then be sorted into other batches where the deviation of the measured actual value from the required target value is within a maximum tolerance upwards or in another batch downwards, and in another batch, for example, all parts can be sorted that exceed the maximum tolerance and are therefore scrap or transferred for reprocessing.

[0014] In a further development of the method according to the invention, a processing device with several processing stations is used to carry out the method, wherein the processing stations include a feed station for feeding unmachined piston blanks, a laser station for producing the overflow hole, a measuring station for measuring the produced overflow hole and an ejection station for ejecting the measured damper pistons.

[0015] In a particularly preferred manner, the processing device comprises a conveyor device which is used to transport the damper pistons between the processing stations.

[0016] The conveyor device can, for example, be a rotary table assigned to all processing stations, which moves the damper pistons located thereon in cycles between processing stations.

[0017] The invention further relates to a hydraulic damper having the features of independent claim 8.

[0018] The hydraulic damper according to the invention is characterized in that the overflow hole is formed by irradiating the piston body with a laser beam.

[0019] According to the invention, the overflow hole has two oppositely arranged orifice sections that are connected to each other via a central section, with the orifice sections being funnel-shaped relative to the central section. The overflow hole can therefore have a conical shape.

[0020] The invention further comprises a movement device for opening and closing a movable furniture part, in particular a drawer, door or flap, characterized by at least one hydraulic damper according to claim 8.

[0021] In a further development of the movement device, this is designed as a fitting, in particular a flap fitting, with a lever device, with several levers which are connected to one another in an articulated manner and which are pivotally mounted on the one hand on the furniture and on the other hand on a movable furniture part, wherein the hydraulic damper is preferably arranged on a mounting plate belonging to the fitting, which in turn can be fastened to the furniture.

[0022] Alternatively, it is possible for the movement device to be designed as a hinge, with a first hinge part assigned to a piece of furniture, in particular in the form of a hinge arm, and a second hinge part assigned to a movable piece of furniture, for example a door, in particular in the form of a hinge cup, wherein the hydraulic damper is preferably arranged on the furniture-side first hinge part.

[0023] A preferred embodiment of the invention is illustrated in the drawing and explained in more detail below. The drawing shows: Figure 1 shows a schematic representation of a preferred embodiment of a processing device for carrying out the method according to the invention for producing a hydraulic damper, Figure 2 shows a longitudinal section through part of a hydraulic damper produced by the method according to the invention, Figure 3 shows a graph for force measurement of various dampers at constant temperature and constant speed over the distance traveled, Figure 4 shows a diagram in which the force of various dampers is plotted against the diameter, and Figure 5 shows a further development of the diagram of Figure 4 in which the different force / diameter coordinates of the different dampers are connected by a curve.

[0024] Figure 1shows a preferred embodiment of a processing device 11 in which the method according to the invention for producing a hydraulic damper 12 ( Figure 2 ). Such hydraulic dampers 12 have countless fields of application, but the hydraulic damper 12 according to the invention will be described here by way of example for use in a movement device for a piece of furniture.

[0025] As exemplified in Figure 2 As shown, such a hydraulic damper 12 comprises a damper housing 13 in which a damper piston 14 is received. The damper piston 14 is connected to a piston rod 15, which extends out of the damper housing 13 via an opening (not shown).

[0026] It is possible for the piston rod 15 and the damper piston 14 to be movably mounted, while the damper housing 13 is stationary. In this case, the damper piston 14 is movably guided within the damper housing 13. Alternatively, however, it is also possible for the damper piston 14 and the piston rod 15 to be stationary, while the damper housing 13 is movably guided.

[0027] The damper piston 14 has a piston body 16 which is axially penetrated by at least one overflow hole 17 through which damping fluid can flow during the damping process.

[0028] Hydraulic oil is preferred as the damping fluid.

[0029] Conveniently, the hydraulic damper 12 is a plastic component. Conveniently, the main components of the hydraulic damper, i.e., the damper housing 13 and the damper piston 14 with the piston body 16, are plastic components, which are manufactured in particular by means of plastic injection molding.

[0030] As particularly in Figure 2 As shown, the piston body 16 of the damper piston 14 has a piston rod channel 18 which is preferably arranged substantially parallel to the overflow hole 17. As shown by way of example in Figure 2As shown, the piston rod channel 18 is penetrated by the piston rod 15. For example, the piston rod 15 has several piston rod sections 19a, 19b, 19c with different diameters, wherein, in particular, a piston rod section 19c located at the free end has a larger diameter than the diameter of the piston rod channel, whereby the piston rod is mounted on the piston body 16 so that it cannot be axially displaced in one direction. A step between the first and second piston rod sections 19a, 19b ensures securing in the other direction.

[0031] The transition between the inside of the piston rod channel 18 and the outside of the piston rod 15 is sealed by means of an annular seal 20 which sits on the piston rod 15.

[0032] The transition between the outside of the piston body 16 and the inner wall of the damper housing 13 is also sealed by means of an annular seal 21, in the example case by means of an annular cord sealing ring.

[0033] The aforementioned processing device 11, which is used to manufacture hydraulic dampers 12, comprises several processing stations, one of which is a feed station 22 for feeding unmachined piston blanks. The feed station 22 comprises, for example, a conveyor pot 23 in which the piston blanks are stored and then transported to a conveyor device 24, which is also part of the processing device 11. In the example, the conveyor device 24 comprises a turntable 25.

[0034] A further processing station is provided, a laser station 26 for producing the overflow hole 17 in the respective piston body 16 of the damper piston 14. Adjacent to the laser station 26 in the processing direction is a measuring station 27, which serves to measure the produced overflow hole 17.

[0035] The last of the processing stations is a discharge station 28, where the finished damper pistons are discharged.

[0036] In the example case, the discharge station 28 comprises several collecting containers 29a-d, into which piston bodies 16 are sorted depending on the measurement result when measuring the respective overflow hole 17.

[0037] The rotary table 25 is thus assigned to each of the processing stations, with damper pistons 14 located thereon being moved in cycles between the processing stations.

[0038] The inventive method for manufacturing hydraulic dampers 12 proceeds as follows: The components, damper housing 13 and damper piston 14, are first manufactured by plastic injection molding. The unmachined piston blanks, in particular the piston body 16 of the damper piston 14, are stored in the feeder bowl 23. The unmachined piston blanks are fed into the turntable 25 via the feeder bowl 23. During the next cycle, the fed piston blanks are transferred to the laser station 26.

[0039] In the laser station 26, the overflow holes 17 are created by irradiating the piston body 16 with a laser beam. It is possible for several overflow holes 17 to be created simultaneously on different piston bodies 16 using multiple laser beams. However, it is also possible to work with only a single laser beam, which then creates the overflow holes 17 one after the other in the piston blanks.

[0040] It is possible for the piston rod channels 18 to be incorporated during the production of the piston blanks by means of plastic injection molding. Alternatively, however, it is also possible to produce the piston rod channel 18 in addition to the overflow hole 17 by means of laser irradiation. Machining the piston blanks by means of laser irradiation can be carried out by laser beam cutting, in particular by laser flame cutting.

[0041] The advantage of laser-cutting the overflow hole 17 compared to conventional plastic injection molding with pre-formed overflow holes 17 is the significantly higher level of precision. This significantly reduces the scrap rate, particularly for hydraulic dampers with relatively low damping forces. For example, a damper with a damping force of 30 N would require an overflow hole with a diameter of 0.18 mm to precisely provide the required damping force for 30 N. The maximum tolerance permitted for this would be + / - 2 N, which corresponds to a maximum tolerance of + / - 0.005 mm at 0.18 mm. This is impossible from an injection molding perspective, as tolerances here are approximately + / - 0.02 mm.

[0042] After the overflow hole 17 has been created by laser irradiation, the rotary plate 25 is further cycled and the piston body 16 provided with the overflow hole 17 reaches the measuring station 27.

[0043] In the measuring station 27, the overflow hole 17 is measured. In particular, the actual diameter of the overflow hole 17 is measured. The measured actual diameter of the overflow hole 17 is compared with a stored target diameter value. This is conveniently done using a control device, which is also part of the processing device 11 and in which the required target values ​​are stored as a function of the damper force.

[0044] After measuring the overflow hole 17, the turntable 25 is cycled further, and the piston body 16 with the measured overflow hole 17 reaches the discharge station 28. At the discharge station 28, the piston body 16 equipped with the overflow hole 17 is sorted into one of the collection containers 29a-d. Sorting is carried out, for example, according to the following criteria: Piston bodies 16 that exhibit only minimal deviations between the actual value of the overflow hole diameter and the required target value are sorted into the first collection container 29a. Piston bodies whose actual value of the overflow hole diameter 17 is larger than the required target value, but does not exceed a maximum upper tolerance, are sorted into the second collection container 29b. Piston bodies whose actual value is smaller than the required target value, but which do not fall below a maximum tolerance, are sorted into the third collecting container 29c.Piston bodies whose actual value of the measured diameter of the overflow hole 17 exceeds the maximum permissible tolerance either upwards or downwards are sorted into the fourth collecting container 29d. Those piston bodies whose actual value falls below the maximum permissible tolerance, i.e., those whose overflow holes are significantly too small, can be sent for subsequent reprocessing in the laser station 22 or another reprocessing station. Those piston bodies whose actual value of the diameter of the overflow hole 17 is significantly too large are rejected.

[0045] The Figures 3 to 5 show a procedure for determining the diameter of the overflow hole 17 required for a specific damping force of a hydraulic damper 12.

[0046] For this purpose, the damper pistons 14 are first installed in the damper. A force measurement of the hydraulic dampers 12 is then performed at a specified speed and temperature. The measurement is performed at a constant speed and constant temperature. The measurement is performed at a specified diameter or flow cross-section.

[0047] The diagram in Figure 3 shows a force-displacement diagram in which the force / displacement curves of various hydraulic dampers 12 with a precisely assigned diameter of the overflow hole are shown. The larger the diameter of the overflow hole 17, the higher the measured damping force of the hydraulic damper. The diagram shows the Figure 3 that the damper piston with the largest flow cross-section can apply the highest force, although this maximum force is reached after a longer distance than pistons with smaller flow cross-sections.

[0048] The Figure 4 shows a diagram in which the previously described force measurement (see diagram of the Figure 3 ) measured damper forces are plotted against the diameter.

[0049] The diagram from Figure 5 shows a force / diameter curve. From this curve, the required flow cross-section, i.e., the required diameter of the overflow hole, can be determined for a given force.

[0050] There are already countless applications in the furniture sector for the hydraulic dampers 12 manufactured using the method according to the invention. For example, it is possible to use the hydraulic damper in a movement device in the form of a fitting. In an application variant not shown in the figures, a flap fitting is provided, which has a lever device with several interconnected levers. The levers are pivotally mounted on a piece of furniture and pivotally mounted on a movable furniture part in the form of a flap. In this case, the hydraulic damper 12 can be arranged on a mounting plate belonging to the fitting, which in turn can be fastened to the furniture.

[0051] In one alternative, the movement device is designed as a hinge. The hinge has a first hinge part associated with a piece of furniture, in particular in the form of a hinge arm, and a second hinge part associated with a movable furniture part, for example, a door, in particular in the form of a hinge cup. In this application, the hydraulic damper 12 can be arranged on the first hinge part on the furniture side.

Claims

1. Method for producing a hydraulic damper (12) which has a damper housing (13) and a damper piston (14) accommodated in the damper housing (13) and connected to a piston rod (15), wherein the damper piston (14) has a piston body (16) which is axially penetrated by at least one overflow hole (17) through which damping fluid can overflow during the damping process, the overflow hole (17) is produced by irradiating the piston body (16) using a laser beam, wherein the piston body (16) has a piston rod channel (18) in which the piston rod (15) is accommodated, characterised in that the piston rod channel (18) is produced by irradiating the piston body (16) using a laser beam.

2. Method according to claim 1, characterised in that the piston body (16) is a plastic component.

3. Method according to one of the preceding claims, characterised in that the overflow hole (17) is measured after its production, wherein preferably the channel diameter of the overflow hole (17) is measured.

4. Method according to claim 3, characterised in that the damper piston (14) is sorted into batches after the overflow hole (17) has been measured depending on the measurement result, in particular the measured actual value of the hole diameter, and / or if the deviation of the measurement result from a target value is too great, the overflow hole (17) is reworked, in particular by means of laser irradiation.

5. Method according to one of the preceding claims, characterised in that a processing device (11) with several processing stations is used to carry out the method, wherein of the processing stations a feed station (22) for feeding unprocessed piston blanks, a laser station (26) for producing the overflow hole (17), a measuring station (27) for measuring the produced overflow hole (17) and an ejection station (28) for ejecting the measured damper pistons (14) are provided.

6. Method according to claim 5, characterised in that the processing device (11) has a conveyor device (24) which is used to transport the damper pistons (14) between the processing stations.

7. Method according to claim 6, characterised in that the conveyor device (24) is a rotary plate (25) assigned to all processing stations, which moves the damper pistons (14) located thereon in cycles between the processing stations.

8. Hydraulic damper, with a damper housing (13) and a damper piston (14) accommodated in the damper housing (13) and connected to a piston rod (15), wherein the damper piston (14) has a piston body (16) which is axially penetrated by at least one overflow hole (17) through which damping fluid can overflow during the damping process, wherein the overflow hole (17) is produced by irradiating the piston body (16) by means of a laser beam, characterised in that the overflow hole (17) has two mouth sections arranged opposite one another which are connected to one another via a central section, wherein the mouth sections are widened in a funnel shape relative to the central section.

9. Movement device for opening and closing a movable furniture part, in particular a drawer, door or flap, characterised by at least one hydraulic damper (12) according to claim 8.

10. Movement device according to claim 9, characterised in that the movement device (11) is designed as a fitting, in particular a flap fitting, with a lever device with several levers which are connected to one another in an articulated manner and which are pivotably mounted both on the furniture and on a movable furniture part, wherein the hydraulic damper (12) is preferably arranged on a mounting plate belonging to the fitting, which in turn can be fastened to the furniture.

11. Movement device according to claim 9, characterised in that the movement device (11) is designed as a hinge, with a first hinge part assigned to a piece of furniture, in particular in the form of a hinge arm, and a second hinge part assigned to a movable piece of furniture, for example a door, in particular in the form of a hinge cup, wherein the hydraulic damper is preferably arranged on the first hinge part on the furniture side.