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DE-102024004627-A1 - Motor spindle for dental milling machine

DE102024004627A1DE 102024004627 A1DE102024004627 A1DE 102024004627A1DE-102024004627-A1

Abstract

The invention relates to a motor spindle (20) for a dental milling machine, comprising an outer housing (9) and a spindle unit (20') arranged in the outer housing (9) with a spindle shaft (3), wherein the spindle shaft (3) has a front and a rear end (16, 17) and extends along a central longitudinal axis (L), an electric drive (1, 2) for electrically driving the spindle shaft (3), wherein a tool holder (5) is arranged at the front end (16) of the spindle shaft (3), which can be rotated about the central longitudinal axis (L) by means of the electric motor (1, 2) during operation of the motor spindle (20), wherein a milling tool (6) with a tool tip (6') can be clamped in the tool holder (5) of the spindle shaft (3) for machining a workpiece. According to the invention, the spindle shaft (3) has a fan wheel (11) which is arranged inside the outer housing (9) and outside an inner housing for the spindle shaft (3) and the electric drive (1, 2), wherein a nozzle head (13') with at least one air outlet nozzle (13) is provided in the region of the front end (16) of the spindle shaft (3), and wherein the fan wheel (11) is configured to rotate about the central longitudinal axis (L) in a direction of rotation (D) intended for chip removal during operation of the motor spindle (20) and to generate an airflow (12') in the direction from the fan wheel (11) towards the at least one air outlet nozzle (13), wherein the at least one air outlet nozzle (13) is configured to direct the airflow (12') from the nozzle head (13') in a non-parallel orientation to the central longitudinal axis (L) towards the tool tip (6') and the to blow out the workpiece being processed.

Inventors

  • Simon Steinle

Assignees

  • SYCOTEC GMBH & CO. KG

Dates

Publication Date
20260513
Application Date
20241013

Claims (16)

  1. Motor spindle (20) for a dental milling machine for machining a workpiece, ▪ with an outer housing (9), ▪ with a spindle shaft (3), ▪ wherein the spindle shaft (3) has a front end (16) and a rear end (17) and extends along a central longitudinal axis (L), ▪ with an electric drive (1, 2) for the spindle shaft (3), ▪ with a tool holder (5), ▪ wherein a milling tool (6) for machining the workpiece can be clamped in the tool holder (5), and ▪ with a fan wheel (11), wherein the fan wheel (11) is arranged inside the outer housing (9) and is mounted non-rotatably on the spindle shaft (3), and ▪ wherein the outer housing (9) has at least one air outlet nozzle (13) in the region of the front end (16) of the spindle shaft (3) and/or in the region of the tool holder (5), characterized in this respect , ▪ that the fan wheel (11) is designed to rotate about the central longitudinal axis (L) in a direction of rotation (D) intended for chip removal during operation of the motor spindle (20) and to generate an airflow (12') within the outer housing (9) in the direction of the at least one air outlet nozzle (13), and ▪ that the at least one air outlet nozzle (13) of the outer housing (9) is designed to blow the airflow (12') out of the outer housing (9) in a non-parallel orientation to the central longitudinal axis (L) in the direction of the milling tool (6) and/or the workpiece to be machined.
  2. motor spindle after Claim 1 , characterized in that the at least one air outlet nozzle (13) is formed between the outer housing (9) and the tool holder (5).
  3. motor spindle after Claim 2 , characterized in that the at least one air outlet nozzle (13) is part of a nozzle head (13').
  4. Motor spindle according to one of the preceding claims, characterized in that the fan wheel (11) is arranged on the rear end (17) of the spindle shaft (3).
  5. Motor spindle according to one of the preceding claims, characterized in that the fan wheel (11) is arranged inside the outer housing (9) along the airflow (12') in the direction of the at least one air outlet nozzle (13) in front of the electric drive (1, 2).
  6. Motor spindle according to one of the preceding claims, characterized in that the spindle shaft (3) and the electric drive (1, 2) are part of a spindle unit (20'), wherein the spindle unit (20') is arranged inside the outer housing (9) in an inner housing (9') and wherein the fan wheel (11) is formed outside the inner housing (9').
  7. motor spindle after Claim 6 , characterized in that the airflow (12') generated by the fan wheel (11) is guided between the inner housing (9') of the spindle unit (20') and the outer housing (9) of the motor spindle (20).
  8. Motor spindle according to one of the preceding claims, characterized in that the outer housing (9) has at least one air intake channel (14) for drawing in ambient air during operation of the fan wheel (11) and the spindle shaft (3).
  9. Motor spindle according to one of the preceding claims, characterized in that the outer housing (9) of the motor spindle (20) has a tapered section (9") in the area of the front end (16) of the spindle shaft (3) and/or in the area of the tool holder (5) which reduces a flowable cross-section of the airflow channel (12).
  10. Motor spindle according to one of the preceding claims, characterized in that the inner housing (9') of the spindle unit (20') has and/or forms air guide elements (15) at least in sections.
  11. Motor spindle according to one of the preceding claims, characterized in that the spindle shaft (3) is rotatably mounted in bearings (4), wherein the bearings (4) are arranged inside the inner housing (9').
  12. Motor spindle according to one of the preceding claims, characterized in that the outer diameter of the fan wheel (11) is smaller than the outer diameter of the inner housing (9') of the spindle unit (20').
  13. Motor spindle according to one of the preceding claims, characterized in that the tool holder (5) is formed at the front end (16) of the spindle shaft (3).
  14. Motor spindle according to one of the preceding claims, characterized in that the motor spindle (20) can be operated without compressed air.
  15. Dental milling machine with at least one motor spindle (20) according to one of the preceding claims.
  16. Method for cleaning and cooling a milling tool and/or a workpiece in a dental milling machine according to Claim 16 by means of a motor spindle (20) according to one of the Claims 1 until 15 .

Description

The invention relates to a motor spindle for a dental milling machine according to the preamble of claim 1, a dental milling machine with a motor spindle according to claim 15 and a method for cleaning and cooling a milling tool and/or a workpiece to be machined according to claim 16. In dental technology, blanks made of various materials are machined to produce dental prostheses such as crowns, bridges, and the like. This machining is carried out in specialized machines, particularly dental milling machines. These machines typically consist of a motor spindle with a milling tool, which is usually clamped to the front end of the motor spindle for machining a workpiece. The manufacturing process consists of several machining operations, such as milling, grinding, and polishing. Machining removes material, specifically chips, cutting dust, and polishing dust, which accumulates on the workpiece and in the motor spindle or dental milling machine. If the workpiece becomes clogged with this material, it can damage the milling tool and the workpiece. To avoid this, the workpiece is cleaned with compressed air or coolants such as cooling water during processing. When machining materials such as ceramics or titanium using wet machining, the workpiece and/or the milling tool is cleaned and cooled with a cooling lubricant during the milling process. When machining materials that are processed dry, such as zirconia, the workpiece and/or the milling tool are cleaned and cooled with compressed air during the milling process. Compressed air compressors can serve as the compressed air source, either integrated into the dental milling machine or provided as external, stationary units. Such compressed air systems are maintenance-intensive and expensive. If the compressed air compressors are integrated into the machine, they also take up installation space and can affect the external dimensions and the use of the motor spindle. If external, stationary units are used, additional floor space is required, and appropriate piping connections must be installed. To counter this, he proposes EP 4 201 588 A1 This document describes a special milling tool for a dental milling machine and an assembly consisting of a motor spindle and such a milling tool. A mounting section for attaching a fan wheel is arranged directly on the milling tool or on a shank of the tool. The fan wheel is designed such that when the milling tool is driven in a specific direction of rotation, an airflow is generated by the fan wheel in the direction of the milling tool. The mounting section and the fan wheel are located on the outside of the tool and are visible from the outside during machining. The fan wheel is mounted and secured to the spindle shaft from the outside and is therefore dimensioned larger than the spindle shaft in terms of diameter and external dimensions, particularly in the radial direction. A disadvantage of this design is that sufficient focusing or alignment of the generated air volume at a sufficiently high pressure is not possible. This significantly reduces energy efficiency and the effectiveness of cleaning and cooling. The fan wheel is fixed directly to the milling tool. It generates an airflow towards the workpiece, but this flow runs almost parallel to the shank of the milling tool. As a result, adequate cleaning and cooling can only be achieved at very high speeds, which are not attainable at the speeds typical for dry machining. Therefore, additional blow-off cycles during machining are absolutely necessary to achieve sufficient airflow. These additional blow-off cycles consume extra energy without any cleaning or cooling effect, further increasing energy losses and reducing efficiency even more. Due to the large size of the blower wheel/fan wheel compared to the entire motor spindle/dental milling machine, the use of the motor spindle is further limited. Because of the blower wheel's relatively large size, only a small number of tools can be stored in the tool magazine, requiring a correspondingly large grid. The use of standard tools is not possible. The aim of the invention is to overcome these and other disadvantages of the prior art and to provide an improved motor spindle for a dental milling machine that is simple in design, cost-effective and efficient. The main features of the invention are specified in claims 1, 15 and 16. Embodiments are the subject of claims 2 to 14. In a motor spindle for a dental milling machine for machining a workpiece, comprising an outer housing, a spindle shaft (the spindle shaft having a front end and a rear end and extending along a central longitudinal axis), an electric drive for the spindle shaft, a tool holder (in which a milling tool for machining the workpiece can be clamped), and a fan wheel (the fan wheel being arranged inside the outer housing and non-rotatably mounted on the spindle shaft), and the outer housing having at least one air outlet nozzle in the region of the front end of