Pressure plate for polishing ceramic implants, especially hip joint implants.

Abstract

Pressure plate (1) for receiving a plurality of ceramic components (2), in particular implants for endoprostheses, for polishing in a polishing tool, characterized in that the pressure plate (1) has radially symmetrically arranged struts (3), at the ends of which a receiving device (4) for receiving a part guide (5) is arranged, wherein all part guides (5) are identical, each receiving only one component (2), are adapted to the component (2) and anchor it via a conical clamp.

Description

[0001] The invention relates to a pressure plate for receiving a plurality of ceramic components, in particular implants for endoprostheses, for polishing in a polishing tool.

[0002] In the production of implants for endoprostheses, particularly ceramic hip sockets for ceramic femoral heads, a green body is first formed. Before sintering, this green body is milled on its top and bottom surfaces to precisely adapt the contour to the requirements. After milling, the green body is sintered. These implants are subsequently referred to as components.

[0003] After sintering, for example, the top surface of the component facing the artificial sliding partner must be polished to obtain a smooth surface.

[0004] For this reason, components to be polished are placed in a pressure plate, and this pressure plate is then clamped into the polishing tool. This allows multiple components to be polished in a single operation.

[0005] Existing pressure plates used for polishing only accommodate a fixed number of components and do not offer flexible adaptation to different component configurations. Furthermore, the component guides cannot be easily disassembled. In particular, controlled force transmission to sensitive ceramic implants presents a challenge.

[0006] The invention is therefore based on the objective of providing a pressure plate for receiving a plurality of ceramic components, in particular implants for endoprostheses, for polishing in a polishing tool, which allows flexible adaptation to different component configurations, transmits the contact force specifically to ceramic implants and enables easy maintenance and exchangeability of the entire part guide and / or the individual part guide components.

[0007] This problem is solved by a printing plate according to the features of claim 1.

[0008] Because the pressure plate has radially symmetrical struts, each with a receiving device at its end for a part guide, and because all part guides are identical, each holding only one component, adapted to the component, and anchored via a conical clamp, the pressure plate can accommodate multiple ceramic components for polishing in a single polishing tool. This allows for flexible adaptation to different component configurations. Furthermore, the contact force is precisely transferred to the ceramic components, and simple maintenance and replacement of the entire part guide and / or individual part guide components are facilitated.

[0009] In a preferred embodiment, each part guide is interchangeably mounted in the receiving device, so that the part guides are easy to assemble and disassemble.

[0010] Preferably, the component guides are screwed into the receiving device.

[0011] The component guide advantageously consists of a cylindrical base body with a centering bolt projecting axially. This bolt serves both for centering and for fastening.

[0012] Preferably, a thread is arranged on the outer surface of the bolt or the base body for fastening the part guide in the receiving device.

[0013] In a preferred embodiment, the side of the component guide facing away from the bolt has a component receptacle with a wall that is inclined to the longitudinal axis of the component receptacle. Circumferential grooves are located in the wall of the component receptacle, in which O-rings are inserted. These O-rings clamp the component in contact with the product and transmit the clamping force from the pressure plate to the component. The angled wall, relative to the longitudinal axis of the component receptacle, results in the conical clamping of the components within the component receptacle of the component guide.

[0014] Advantageously, at least two, preferably three, circumferential grooves with O-rings are arranged in the wall of the component holder. This ensures that the components are firmly anchored.

[0015] As already explained, the grooves are preferably arranged at an angle to the longitudinal axis of the component or the guide, so that the O-rings create a conical clamping effect. To enable the O-rings to fulfill their function, they are preferably made of an elastic, force-transmitting material, preferably FPM (Viton) peroxide-cured.

[0016] When the components are inserted into the component holder, a negative pressure is created, which makes assembly and disassembly difficult or impossible. Therefore, the inner end of the component holder, facing the bolt, is preferably connected to the atmosphere via a relief hole.

[0017] To eject the O-rings from the conical grooves, disassembly bores are advantageously arranged in the base body, extending to the conical grooves in the component holder, into which a tool for ejecting the O-rings from the grooves can be inserted. This tool can be a pin.

[0018] The preferred implants for endoprostheses are ceramic hip sockets for receiving ceramic ball heads.

[0019] The printing plate according to the invention is preferably used for single-sheet polishing (SPPB).

[0020] The invention is explained in more detail below using figures.

[0021] They show: Fig. 1: A top view of a pressure plate according to the invention for receiving ceramic components for polishing in a polishing tool and Fig. 2: a cross-section through a part guide with the component inserted.

[0022] Fig. Figure 1 shows a top view of a pressure plate 1 according to the invention for receiving ceramic components 2 for polishing in a polishing tool. The pressure plate 1 shown here has 16 (sixteen) radially symmetrically arranged struts 3, at the ends of which a receiving device 4 for part guides 5 is attached. The part guides 5 are completely removable from the pressure plate 1 and replaceable. The embodiment of the pressure plate 1 shown here exhibits complete coverage (100% part coverage). Partial coverage is also possible.

[0023] The number of required struts 3 and component guides 5 depends on the requirements and can be configured accordingly. All holding devices 4 and component guides 5 are arranged concentrically to the longitudinal axis of the pressure plate 1, meaning they are equidistant from the longitudinal axis. The radially symmetrical arrangement of the struts 3 with adjacent slots 18 results in flexible support.

[0024] Fig. Figure 2 shows a cross-section through a component guide 5 with component 2 inserted. In this case, component 2 is a ceramic hip socket used in an artificial hip joint.

[0025] Each component guide 5 is a separate, demountable and replaceable unit integrated radially into the pressure plate. It serves to securely fix ceramic hip joint implants, e.g., acetabular inserts, during the polishing process and to transmit the contact force in a defined manner.

[0026] Each component guide 5 consists of a cylindrical base body 6 with a centering bolt 8 projecting in the direction of the longitudinal axis 7, i.e., in the axial direction 13, and a component receptacle 11 for the component 2 on the side opposite the bolt 8. The base body 6, or component guide 5, is placed on the pressure plate 1 and, in this embodiment, fastened by means of a screw thread. For this purpose, a thread 10 is provided on the cylindrical surface 9 of the bolt 8. This thread can also be located on the cylindrical surface of the base body 6. According to the drawing, centering is achieved via a specially shaped guide geometry adapted to the respective component 2. This ensures that the component 2 is precisely aligned and machined uniformly. The bolt 8 and / or the cylindrical surface of the base body 6 serve this purpose.

[0027] Inside the base body 6, i.e., projecting into the base body 6, is the component receptacle 11 with a wall 12 that is inclined, in this embodiment at 50°, to the longitudinal axis 7 of the component receptacle 11 or the base body 6. This wall 12 forms a conical 50° funnel for receiving the component 2. The wall 12 of the component receptacle 11 has three circumferential grooves 14, each serving to receive an O-ring 15. These grooves 14 are inclined to the longitudinal axis 7 of the component 2, so that the O-rings 15 create a conical clamping effect. This inclined orientation results in radial and axial fixation of the component 2 or the implant.

[0028] The O-rings 15 are made of an elastic, force-transmitting material. They are in contact with the product, i.e., they touch component 2 and transmit the contact force from the pressure plate 1 to the respective component 2. The O-rings 15 prevent damage in the form of shiny spots and / or microcracks on the sensitive component 2.

[0029] To prevent a vacuum effect, a relief hole 16 is provided in each component guide. The relief hole 16 is centrally located in the axial direction and, in this case, is situated at the lowest point of the component receptacle 11 or the conical funnel. The relief hole 16 is connected to the atmosphere via bores. In the drawing, the relief hole 16 is shown as a unit together with the bores. The relief hole 16 serves to allow air to escape when the implant is inserted. This prevents the formation of a vacuum, which would make insertion or removal difficult.

[0030] To facilitate the removal of the O-rings 15 from the grooves 14, the grooves 14 are connected to the atmosphere via disassembly bores 17. A tool, e.g., a pin, can be inserted into these disassembly bores 17 to push the O-rings 15 out of the grooves 14. The disassembly bores 17 can also be disassembly openings and can be arranged radially.

[0031] The number and position of the part guides 5 are variable depending on the production scenario (part occupancy). These part guides 5 can be quickly changed to process different sizes of components or implants.

[0032] Advantages of the invention: • Flexibility in different production scenarios. • Uniform and defined force transmission to sensitive components. • Easy maintenance and replaceability of wear parts. • Avoidance of vacuum effects during processing. Reference symbol list: 1 printing plate 2 components 3 struts 4 Recording device 5 parts guide 6 basic shapes 7 Axial direction 8 bolts 9 Surface area 10 threads 11 Component intake 12 Wall 13 Longitudinal axis 14 grooves in a conical arrangement 15 O-rings 16 Relief borehole 17 disassembly holes 18 gaps

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