Tool holder

Abstract

The present invention relates to a tool holder 100 for receiving a tool 200, comprising a housing 10, a transmission element 20 movably arranged in the housing 10 for transmitting a movement to the tool 200 received at a first end section 30 of the tool holder 100, a fastening section 40 on a second end section 50 of the tool holder 100 opposite the first end section 30 of the tool holder 100 for fastening the tool holder 100 to a machine tool 300, and a coolant line section 60 for conveying coolant from the second end section 50 of the tool holder 100 to the first end section 30 of the tool holder 100, wherein the coolant line section 60 has a first subsection 61 extending through the transmission element 20, wherein the first subsection 61 is at least partially formed as a bore in the transmission element 20.

Description

[0001] The present invention relates to a tool holder for receiving a tool, comprising a housing, a transmission element movably arranged in the housing for transmitting a movement to the tool received at a first end section of the tool holder, a fastening section on a second end section of the tool holder opposite the first end section of the tool holder for fastening the tool holder to a machine tool, and a coolant line section for directing coolant from the second end section of the tool holder to the first end section of the tool holder. BACKGROUND OF THE INVENTION

[0002] In the prior art, tool spindles for use in a machine tool are known which have a continuous inner tube for cooling and lubricating the tool during workpiece machining, through which the coolant is directed to the tool.

[0003] EP 1 480 783 B1 describes a machine tool with a spindle having a tool holder for an interchangeable tool holder, which is clamped into the tool holder during operation of the machine tool and which has a coolant tube for receiving a coolant lubricant, furthermore with a first channel arranged inside the spindle with an outlet opening that opens inside the tool holder, wherein the coolant tube engages in the outlet opening of the first channel when the tool holder is clamped in place, wherein the first channel includes a continuous inner tube, the first end of which is connected to an aerosol source and the second end of which is designed for a precise connection to the coolant tube.

[0004] In addition, tool holders for ultrasonic machining of workpieces are known, in which the tool holder is set into vibration by a piezo system.

[0005] EP 1 763 416 B1 describes a tool with a tool holder and a spindle nose, wherein the tool holder has at a first end a tool holder receptacle for adaptation to the rotatable spindle nose, and at a second end a tool receptacle, and with a tool head that can be inserted into the tool receptacle, wherein the tool holder and the spindle nose form a vibration motor and the vibration motor sets the tool holder into vibration via a piezo system and the piezo system comprises a first stationary coil and a second coil spaced apart from it and acting on the tool holder, wherein the second coil is connected to piezo actuators.

[0006] When using a coolant tube in an oscillating tool holder, one end of the coolant tube, facing the spindle, is rigidly connected to the housing of the oscillating tool holder. At the other end of the coolant tube, facing the tool, the tube must be sealed using a suitable sealing element. This sealing element is positioned close to the vibration node of the oscillating system to prevent stress on the sealing element caused by the continuous vibration. However, this design presents the problem that the tube cross-section and the resulting coolant flow rate are too small to ensure optimal cooling of the tool. Furthermore, the oscillating drive cannot be adequately cooled either. SUMMARY OF THE INVENTION

[0007] One object of the present invention is therefore to provide a tool holder with optimized coolant flow.

[0008] This problem is solved by a tool holder according to claim 1. The dependent claims relate to advantageous embodiments of the tool holder according to the invention.

[0009] The tool holder according to the invention for receiving a tool comprises: a housing, a transmission element movably arranged in the housing for transmitting a movement to the tool received at a first end section of the tool holder, a fastening section on a second end section of the tool holder opposite the first end section of the tool holder for fastening the tool holder to a machine tool, and a coolant line section for directing coolant from the second end section of the tool holder to the first end section of the tool holder, wherein the coolant line section has a first subsection extending through the transmission element, and wherein the first subsection is at least partially formed as a bore in the transmission element.

[0010] The coolant line section consists of the parts of the tool holder that come into contact with the coolant. If the coolant flows directly through the bore in the moving part of the tool holder, instead of through a separate, thin-walled tube inserted through the bore (which can be easily damaged during assembly, for example), this increases the stability of the assembly. For instance, the transmission element can be set into vibration and transmit this vibration to the tool. The housing and mounting section of the tool holder do not vibrate. Thus, the coolant is guided through a non-vibrating section and a vibrating section of the tool holder on its way to the tool.The design according to the invention eliminates the need for a double-walled coolant passage, allowing for a larger cross-section to be used to direct the coolant to the tool. This increases the volume flow rate of the coolant directed towards the tool. Furthermore, the pressure at which the coolant is forced through the coolant line section can be increased due to the greater wall thickness of the coolant channel and the associated increased pressure resistance of the assembly. This allows for improved cooling of the tool and sections of the tool holder in the vicinity of the bore. Ultimately, this results in higher precision during workpiece machining.

[0011] Preferably, the coolant line section has a second sub-section extending through the fastening section, wherein the first sub-section and the second sub-section are arranged to be movable relative to each other.

[0012] This has the advantage that movement of the transmission section, for example a vibration, relative to other parts of the tool holder can be absorbed by a corresponding movement of the first section of the coolant line relative to the second section. The coolant line can also consist of three or more sections that are movable relative to each other.

[0013] Preferably, the first subsection has a first connecting section at an end facing the second subsection for connection with the second subsection, and the second subsection has a second connecting section at an end facing the first subsection for connection with the first subsection, wherein the first connecting section and the second connecting section are joined together.

[0014] Such a design of the connection between the two, mutually movable sections of the coolant line has the advantage that the two connecting sections always overlap even when parts of the tool holder move, thus ensuring that a continuous coolant channel exists in the tool holder.

[0015] Preferably, the first connecting section is designed as a hollow pin and arranged on the first subsection of the coolant line section in such a way that the bore in the transmission element is continued through an interior of the hollow pin, and preferably the second connecting section surrounds the first connecting section completely to introduce the coolant from the second subsection into the first subsection.

[0016] This has the advantage that the coolant can be directed from the fixed or non-vibrating part of the tool holder to the moving or vibrating part of the tool holder without seeping into the interior of the tool holder outside the coolant line section.

[0017] Preferably, the tool holder has a sealing element arranged between the first connecting section and the second connecting section to seal against the escape of coolant from the coolant line section.

[0018] This has the advantage that even if the connecting sections move relative to each other, no coolant can escape from the coolant line section.

[0019] Preferably, the sealing element is designed as a ring made of plastic, which is pressed against an outer wall of the first connecting section.

[0020] Thus, the connection between the first section and the second section of the coolant line can be reliably sealed.

[0021] Preferably, the outer wall of the first connecting section is ground.

[0022] This has the advantage that if the first connecting section moves relative to the surrounding second connecting section, the first connecting section does not get stuck on the second connecting section, so that no mechanical stresses are built up that could lead to damage to the sealing element.

[0023] Preferably, the tool holder has an ultrasonic transducer connected to the transmission element for generating an ultrasonic vibration for the tool, wherein The ultrasonic transducer, the transmission element and the first part of the coolant line section form a vibrating system in the housing, the coolant line section is arranged centrally in the tool holder, and the ultrasonic transducer at least partially surrounds the bore in the transmission element for cooling of the ultrasonic transducer by the coolant in the bore.

[0024] Such an arrangement of the coolant-carrying elements of the tool holder and the ultrasonic transducer within the tool holder has the advantage that the coolant can be used not only to cool the tool but also to cool the ultrasonic transducer. This is particularly important to prevent heat-induced changes in the vibration parameters of the vibrating system and the tool.

[0025] For a tool holder with a vibration-sensitive system, the sealing of the first and second connection sections must occur at the point of maximum vibration amplitude in the design according to the invention. Therefore, it is all the more important for such a tool holder that the surface of the first connection section is ground smooth to prevent abrasion of the sealing material.

[0026] Preferably, the bore in the transmission element is designed such that the coolant flows through the transmission element using a flow cross-section of at least 4.9 mm². 2 and / or occurs at a pressure of at least 60 bar.

[0027] For example, the bore can have a diameter of 2.5 mm. Since the design according to the invention eliminates the need for an additional coolant pipe in the bore, the full width of the bore can be used for coolant flow, resulting in a 20% higher flow rate compared to conventional coolant feedthroughs and a coolant pressure of up to 80 bar in the tool holder. This significantly increases the efficiency of both internal and tool cooling.

[0028] Preferably, the first subsection has a branch and the transmission section has a plurality of openings in the coolant line section such that the coolant is directed from the branch to the openings.

[0029] The openings in the form of side outlets are suitable for draining coolant from tools such as drills or milling cutters that do not have an internal channel. The coolant flow continues to cool the piezoelectric drive. Furthermore, the relatively higher pressure can also be used for external cooling of the tool.

[0030] Preferably, the tool holder has a deflecting element that can be replaced on the tool holder to deflect the coolant exiting the openings in a direction towards the tool held on the tool holder.

[0031] This has the advantage that a rapid adaptation of the coolant jet geometry to the tool used is achieved.

[0032] Preferably, the tool holder has a stabilizing element arranged circumferentially around the first connecting section and the second connecting section to stabilize a connection between the first subsection of the coolant line section and the second subsection of the coolant line section.

[0033] This has the advantage that the area of ​​the tool holder, where the sections of the coolant line are connected, becomes more stable.

[0034] Preferably, the coolant is air, water, or an emulsion.

[0035] Air and water have the advantage of being inexpensive to provide. An emulsion has the advantage of high lubricating properties.

[0036] A machine tool according to the invention has the tool holder according to the invention, wherein the tool received in the tool holder and parts of the tool holder arranged in the housing of the tool holder can be cooled along an axial direction of the tool holder during workpiece machining by the coolant in the coolant line section. BRIEF DESCRIPTION OF THE FIGURES Fig. Figure 1 shows an embodiment of a tool holder according to the invention as a sectional view. Fig. Figures 2A / B show a further embodiment of a tool holder according to the invention as a sectional view. DETAILED DESCRIPTION OF THE FIGURES AND PREFERRED EXAMPLES OF THE PRESENT INVENTION

[0037] The present invention will now be described and explained in detail with reference to exemplary embodiments and exemplary figures.

[0038] Fig. Figure 1 shows a sectional view of an embodiment of a tool holder 100 according to the invention. The tool holder 100 is designed as a longitudinal element with a first end section 30 and a second end section 50, which is opposite the first end section 30. A tool (not shown) can be received on the first end section 30. A mounting section 40 is formed on the second end section 50, by means of which the tool holder 100 can be interchangeably attached to a machine tool.

[0039] The tool holder 100 has a housing 10 in which a vibrating system comprising an ultrasonic transducer 70 and a transmission element 20 is arranged. The ultrasonic transducer 70 has stacked disc-shaped piezoelectric elements which are excited to a mechanical ultrasonic vibration by a generator (not shown). This vibration is transmitted to the transmission element 20 via the mechanical coupling of the ultrasonic transducer 70 and from there to the tool.

[0040] For the purpose of tool cooling and lubrication during the machining of a workpiece, the tool holder 100 has a coolant line section 60, through which coolant is guided from an opening of the coolant line section 60 in the area of ​​the mounting section 40 through the tool holder 100 to an opening of the coolant line section 60 in the area of ​​the transmission section 20 and exits from this opening under pressure.

[0041] In the transmission element 20, a first subsection 61 of the coolant line section 60 is designed as a bore, to which a first connecting section 63 in the form of a hollow stud is attached. The hollow stud 63 is completely surrounded by a second connecting section 64, which may be designed as a section of a tube. The second connecting section 64 has an inner diameter that is only slightly larger than the outer diameter of the hollow stud 63. The opening of the hollow stud 63 is positioned within the second connecting section 64 at a distance from an opening of the connecting section 64.

[0042] The cavity in the second connecting section 64 is part of a second subsection 62 of the coolant line section 60, which connects to the first subsection 61 of the coolant line section 60. The cavity in the second connecting section 64 can be continued through a channel in a transition section 66 of the coolant line section 60. The channel can be continued through a pipe section 67, which is connected to a device (not shown) that introduces coolant into the tool holder 100. In this embodiment, the channel in the transition section 66 and the pipe section 67 are also part of the second subsection 62 of the coolant line section 60. In this way, coolant can be routed from the second end section 50 of the tool holder 100 through the entire length of the coolant line section 60 to the tool at the first end section 30 of the tool holder 100.

[0043] During ultrasonic vibration of the vibrating system, the parts of the tool holder 100 that form the first section 61 of the coolant line section 60, namely the transmission section 20 and the hollow pin 63, vibrate. The parts of the tool holder 100 that form the second section 62 of the coolant line section 60 do not vibrate. The hollow pin 63 therefore vibrates within the second (non-vibrating) connection section 64. To prevent the hollow pin 63 and the second connection section 64 from coming into direct mechanical contact, the pin wall is ground, and a sealing element 65 in the form of an O-ring is pressed against the hollow pin 63 in the annular space between the hollow pin 63 and the second connection element 64.The sealing ring 65 thus ensures a small minimum distance between hollow pin 63 and second connecting section 64 and seals the connection between the first subsection 61 and the second subsection 62 of the coolant line section 60 against leakage of coolant from the coolant line section 60.

[0044] The coolant flows directly into the bore of the transmission section 20. This allows the entire diameter of the bore to be, for example, 2.5 mm, i.e., a cross-sectional area of, for example, 4.9 mm². 2, used to convey the coolant. The wall formed around the bore by the transmission element 20 is relatively thick (thicker than the bore diameter). Furthermore, a stabilizing element 80 is arranged in the housing 10 around the second connection section 64 and around part of the transition section 66. This largely avoids cavities within the housing 10 that are not part of the coolant line section 60. As a result, the coolant can be conveyed through the tool holder 100 at a high pressure of up to 80 bar.

[0045] The ultrasonic transducer 70 is arranged as a ring element around the bore in the transmission section 20, without any cavity in the radial direction between the bore and the ultrasonic transducer 70. The coolant flowing through the transmission section 20 cools the wall around the bore and the direct mechanical contact between the transmission section 20 and the ultrasonic transducer 70, thus also cooling the ultrasonic transducer 70.

[0046] Fig. 2A and Fig. Figure 2B shows a further embodiment of a tool holder 100 according to the invention as a sectional view from two different perspectives, which differs from the embodiment in Fig. 1 differs in that the bore in the transmission section 20 has a branch 68, so that the coolant is directed to several openings 69 located in the transmission section 20 next to the tool. This is important when using tools that do not have an internal coolant channel, such as drills or milling cutters. In this case, the coolant cannot be directed as in Fig. As shown in Figure 1, the coolant is guided through a single opening in the coolant line section 60 and further through the tool to the tool tip. In the case of the coolant line section 60, the coolant is directed through a single opening in the coolant line section 60 and further through the tool to the tool tip. Fig. In the embodiment shown in 2, the coolant is instead distributed from the branch 68 into several channels 71 (e.g., into three channels 71 as in Fig. 2A / B), which can be arranged all around the tool, are directed to the openings 69.

[0047] There, the coolant is directed around the tool to the tool tip by means of a deflection element 21 on the tool holder 100. The deflection element 21 can be interchangeably mounted on the tool holder 100. In this way, the ultrasonic transducer 70 is additionally cooled on the side facing the tool, and the outer surface of the tool is also cooled. LIST OF REFERENCE MARKS 100 tool holders 10 cases 20 transmission element 21 Deflection element 30 first final section 40 fastening section 50 second final section 60 Coolant line section 61 first subsection 62 second subsection 63 first connecting section 64 second connecting section 65 Sealing element 66 Transition section 67 pipe sections 68 branching 69 Opening Channel 71 70 ultrasound transducers 80 stabilizing element

Claims

[1] Tool holder (100) for holding a tool, with a case (10), a transmission element (20) movably arranged in the housing (10) for transmitting a movement to the tool received at a first end section (30) of the tool holder (100), a fastening section (40) on a second end section (50) of the tool holder (100) opposite the first end section (30) of the tool holder (100) for fastening the tool holder (100) to a machine tool, and a coolant line section (60) for conveying coolant from the second end section (50) of the tool holder (100) to the first end section (30) of the tool holder (100), characterized by , that the coolant line section (60) has a first subsection (61) extending through the transmission element (20), wherein the first subsection (61) is at least partially formed as a bore in the transmission element (20), the coolant line section (60) has a second subsection (62) extending through the fastening section (40), wherein the first subsection (61) and the second subsection (62) are arranged to be movable relative to each other, the first subsection (61) has a first connecting section (63) at an end facing the second subsection (62) for connection with the second subsection (62), the second subsection (62) has a second connecting section (64) at an end facing the first subsection (61) for connection with the first subsection (61), and the first connecting section (63) and the second connecting section (64) are joined together. [2] Tool holder (100) according to claim 1, wherein the first connecting section (63) is designed as a hollow pin and is arranged on the first subsection (61) of the coolant line section (60) such that the bore in the transmission element (20) is continued through an interior of the hollow pin, and the second connecting section (64) completely surrounds the first connecting section (63) for the introduction of the coolant from the second subsection (62) into the first subsection (61). [3] Tool holder (100) according to one of claims 1 to 2, with a sealing element (65) arranged between the first connecting section (63) and the second connecting section (64) for sealing against an escape of coolant from the coolant line section (60). [4] Tool holder (100) according to claim 3, wherein the sealing element (65) is designed as a ring made of plastic which is pressed against an outer wall of the first connecting section (63). [5] Tool holder (100) according to claim 4, wherein the outer wall of the first connecting section (63) is ground. [6] Tool holder (100) according to one of the preceding claims, comprising an ultrasonic transducer (70) connected to the transmission element (20) for generating an ultrasonic vibration for the tool, wherein the ultrasonic transducer (70), the transmission element (20) and the first subsection (61) of the coolant line section (60) form a vibrating system in the housing (10), the coolant line section (60) is arranged centrally in the tool holder (100), and the ultrasonic transducer (70) at least partially surrounds the bore in the transmission element (20) for cooling the ultrasonic transducer (70) by the coolant in the bore. [7] Tool holder (100) according to one of the preceding claims, wherein the bore in the transmission element (20) is designed such that the coolant passes through the transmission element (20) using a flow cross-section of at least 4.9 mm² 2 and / or occurs at a pressure of at least 60 bar. [8] Tool holder (100) according to one of the preceding claims, wherein the first subsection (61) has a branch (68); and the transmission section (20) has a plurality of openings (69) of the coolant line section (60) such that the coolant is directed from the branch (68) to the openings (69). [9] Tool holder (100) according to claim 8, with a deflecting element (21) arranged interchangeably on the tool holder (100) for deflecting the coolant exiting the openings (69) in a direction of the tool received on the tool holder (100). [10] Tool holder (100) according to one of claims 1 to 5, with a stabilizing element (80) arranged circumferentially around the first connecting section (63) and the second connecting section (64) for stabilizing a connection of the first subsection (61) of the coolant line section (60) and the second subsection (62) of the coolant line section (60). [11] Tool holder (100) according to any of the preceding claims, wherein the coolant is air or water or an emulsion. [12] machine tool, with the tool holder (100) according to one of the preceding claims, wherein The tool held in the tool holder (100) and parts of the tool holder (100) arranged in the housing (10) of the tool holder (100) can be cooled along an axial direction of the tool holder (100) during workpiece machining by the coolant in the coolant line section (60).

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