Vibration-damped tool holder

(54) Title: Vibration damped tool holder with viscoelastic damping material (56) Published publications: US Al 6 076 999, DE Al 19 948 891, SU Al 559 779 (47) Abstract:

Tool holder 1 comprising a shank portion 2 intended to be arranged in a tool bracket in a machine tool, a main part 3 on which a shaft is intended to be arranged and a viscoelastic material 4 arranged so that the cutter contacts the tool machine only via the viscoelastic material 4, in which on the shank surface S of the shaft part 2 at least the parts which are intended to be in contact with the machine tool S are provided with a viscoelastic material. The viscoelastic material 4 is fixed to a burring material that year (fist on the shaft part 2 surface of the shaft S ..

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Summary

Tool holder 1 comprising a shank portion 2 intended to be arranged in a tool bracket in a machine tool, a main part 3 on which a cutter is intended to be arranged and a viscoelastic material 4 arranged so that the cutter is in contact with the machine tool only via the viscoelastic material 4, in which on the casing surface 5 of the shank member 2, at least those parts which are intended to be in contact with the machine tool are provided with a viscoelastic material. The viscoelastic material 4 is attached to a support material which is attached to the shank surface 5 of the shaft member 2.

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FIELD

The present invention relates to a vibration damped tool holder.

BACKGROUND OF THE INVENTION

Toolholders in machine tools tend to vibrate and cause noise during operation. Such vibration interferes with the machining process by adversely affecting the accuracy of the result. The vibrations also give rise to a troublesome disturbing noise which degrades the environment in connection with the machine tool.

An ideal machine tool does not give rise to any vibrations, but all energy goes to the machining to be done. In fact, vibrations always occur when the different parts of the machine work against each other. As the machine is worn, changes in the dynamic properties of the machine occur. This means that new types of vibration can occur during different stages of the machine's service life. The vibrations can lead to poor surface finish of the workpiece, further wear on the machine and tools, in the worst case, with irreparable damage as a result.

When processing metallic materials, problems also arise with the high noise level caused by vibrations from machining and machine noise. Hitherto used tools have not had built-in or built-in damping devices of such a type that sufficient sound and vibration damping has been possible. It is important to be able to remove large parts of the vibration sound within the frequency range that is inconvenient for the human ear. It is desirable to reduce the level to below 80 dB.

It is known from US 2426359 A to provide vibration damping material in a longitudinal groove on a tool holder. The purpose is to attenuate the vibrations or at least substantially reduce them.

By WO 02/45892 A1, a tool holder (Figure 14) with a damping element is known. The distance between the damper element and the tool body is such that during machining a relative movement between the tool body and the damper element is allowed.

US 5033340 A discloses a tool holder for several tools. In the coupling surface between each tool and the tool holder there is a recess in which a "damping sandwich construction is arranged. This construction consists of alternating layers of steel and viscoelastic material. This construction is considered to reduce noise.

Previous attempts to solve the problem of vibration have thus included complicated solutions with weights and fluids in cavities in the tool holder intended to pivot in counter phase to the unwanted vibrations and thereby dampen them. Other solutions show materials arranged on the tool surface of the tool holder intended to also swing in the counter phase to dampen the vibrations. These solutions generally mean cumbersome

528 470 sizing and testing procedures before finding the right material and properties, if possible.

Thus, one aspect of the present invention is to provide a tool holder with the ability to more easily dampen vibrations.

BRIEF DESCRIPTION OF THE INVENTION

The present invention therefore has a shaft portion intended to be provided in a tool bracket in a machine tool, a main part on which a cutter is intended to be arranged, and a viscoelastic material arranged so that the cutter contacts the tool machine only via the viscoelastic material, on the shaft portion (2). casing surface (5) is at least those parts which are intended to be in contact with the machine tool provided with a viscoelastic material, and the viscoelastic material is attached to a support material which is attached to the shank portion of the shank portion.

In this way, the tool holder is not in metallic direct contact with the machine tool and therefore has the conditions to dampen vibrations to a large extent. The composite construction of the viscoelastic material and the carrier material provides the drastic damping effect demonstrated by the construction of the present invention.

In a further embodiment of the tool holder according to the present invention, at least the parts which are intended to be in contact with the machine are provided with a viscoelastic material on the shank part of the shank part.

In a further embodiment of the tool holder according to the present invention, the viscoelastic material encloses the shank portion of the shaft portion.

In a further embodiment of the tool holder according to the present invention, the viscoelastic material is divided into a plurality of trays appearing on the shaft portion and disposed adjacent to one another.

In a further embodiment of the tool holder according to the present invention, the washers are punched.

In a further embodiment of the tool holder according to the present invention, coaxially externally, if the viscoelastic material is arranged a metal tube is intended to absorb and equalize the pressure upon clamping.

In a further embodiment of the tool holder of the present invention, the viscoelastic material has grooves arranged in grooves in the casing surface of the shank portion extending along its longitudinal axis.

In a further embodiment, the shaft portion is provided with a cavity.

In a further embodiment, the cavity is a cylindrical bore.

It has been found that with a tool holder according to the present invention, a damping of 500 to 600% can be obtained compared to a conventional tool holder.

DESCRIPTION

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Fig. 1 shows a tool holder according to a first embodiment of the present invention.

Fig. 2 shows a tool holder according to a second embodiment of the present invention.

Fig. 3 shows a cross-section through a shaft portion of a modification of the tool holder according to Figs. 1 or 2 according to the present invention.

Fig. 4 shows a tool holder according to a third embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Referring to Fig. 1, a first embodiment of the invention constitutes a tool holder 1 consisting of a shaft portion 2 and a body portion 3. On the body portion 3, a cutter is intended to be provided. The shaft portion 2 of the tool holder 1 is provided with a viscoelastic material 4 around its casing surface 5. The viscoelastic material 4 in this embodiment is in the form of a sheet or tape, having a thickness of a few tenths of a millimeter, wrapped around a support material, for example an aluminum sheet, wrapped around the casing surface 5 and secured to it by means of an adhesive or the like. . Optionally, around the viscoelastic material 4, a steel tube 6 is provided to distribute the clamping forces more evenly when the tool holder 1 is clamped in a machine tool. The radius of the shaft portion 2 may be smaller than the body portion 3, and the carrier material and the sheet together with the thickness of the steel tube 6 may correspond to this difference, which then causes the outer surface of the steel tube 6 to connect to the outer surface of the body portion 3. It is also possible to attach these to a shank portion to a tool holder of conventional design. Furthermore, the viscoelastic material can enclose as much of the tool holder as possible, which has been shown to provide further favorable damping effects.

Referring now to Fig. 2, a second embodiment of the invention constitutes a tool holder 1. The shank portion 2 of the tool holder 1 is provided with a viscoelastic material 4 on its casing surface 5. The viscoelastic material 4 is formed in this embodiment as a plurality of washers 7 appearing on the shaft portion. 2 and arranged side by side. The washers 7 are attached to a support material, e.g., an aluminum sheet, wrapped around the casing surface 5 and secured to it by means of an adhesive or the like. Optionally, a steel tube 6 is arranged around the washers 7 designed to distribute the clamping forces more evenly when the tool holder 1 is clamped in a machine tool. In the same way as in the embodiment of Fig. 1, the radius of the shaft portion 2 is smaller than the main portion 3 for the outer surface of the steel pipe 6 to connect to the casing surface of the main portion 3.

Referring to Fig. 3, there is shown a modification suitable for both the embodiment of Fig. 1 and Fig. 2. The viscoelastic material 4 here is provided with longitudinally spline-shaped grooves 8 having their corresponding recesses in the form of longitudinal grooves 9 in the shank portion 5 of the shaft portion. The grooves 8 are glued in the grooves 9. The number of grooves can be one or

528 470 more. The modification in Fig. 3 shows 3 grooves which may be considered suitable. The grooves 8 are intended to prevent the viscoelastic material / washers 4/7 from rotating around the shaft portion 2 during operation.

Referring now to Fig. 4, a third embodiment of the invention constitutes a tool holder 1. The tool holder 1 is physically divided into two parts, a front main part 3 intended to receive a cutter, and a rear shaft part 2 intended to be attached to a machine tool. The shaft portion 2 and the body portion 3 are spaced apart by a viscoelastic material 4. The viscoelastic material 4 is attached to each portion 2, 3 by bonding. The viscoelastic material 4 can be arranged anywhere on the tool holder between the insert of the insert in the front end of the tool holder to the area intended for attachment in the machine tool. Preferably, the viscoelastic material 4 is provided at the front end in the manner shown in Fig. 4.

It has been found that if the shank portion of the tool holder is provided with a cavity, preferably a cylindrical bore, the damping properties can be further improved.

By designing the viscoelastic material appropriately, the vibrations can be attenuated.

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