Technical field

The invention concerns a rotary tool with inner cooling which consists of holders of cutting inserts, where the holders project from the rotary tool body, and the rotary tool body is adapted for being clamped onto a carrier disc which is adapted for being attached to a machine-tool spindle which is adapted for being attached by means of an axial screw to the carrier disc of the machine tool, where the carrier disc is provided with a cutting fluid supply inlet.

Background art

Machining of certain materials with the use of solid tools or tools with exchangeable cutting inserts requires cooling/lubrication to be applied during the cutting process. Besides well-known steels, such materials may include nickel or titanium superalloys with a low thermal conductivity which precludes effective heat removal from the cut. Generally, heat is generated during cutting by friction between the tool and work, and by plastic deformation at the point of chip formation. Heat dissipation plays a key role in the tool durability and in the quality of machined surface, mainly in the sense of surface integrity.

Several possible routes have been defined in terms of cooling/lubrication of the cutting part of tool during the cutting process. The fluid is either supplied at normal pressure or at increased pressure, which is known as high-pressure cooling, helping the fluid enter the gap between the chip and the face/flank of the cutting part of the tool. Superalloys are also machined with cooling provided by freezing or, often, with minimum quantity lubrication, and also by dry machining with freezing or cooled air being blown to the cut. Background art includes coolant supply to a milling tool, where one of the options is internal cooling when coolant is supplied to the cutting parts of the tool through the spindle or shaft of the machine-tool via a suitable channel system provided in the tool. For instance, there are disc milling cutters on whose wheel-shaped bodies there are cutting inserts arranged in shaped recesses on the wheel perimeter, beside which there are, for instance, recesses for chip removal. A method is known for connecting these recesses for chips via radial channels with an axial through-hole in the tool body, which enables the fluid to reach individual recesses for chips, and therefore the cutting inserts as well. To achieve this, very deep holes of relatively small diameters must be bored or electrical discharge machined laboriously in the cutting tool body. Such procedures are very costly, and even then, the coolant is often delivered to the cutting inserts in a suboptimal manner.

Patent no. 303363 describes a chip cutting tool which is provided with at least one central internal hole for the cooling or lubricating medium and whose major or minor flank has near the associated cutting edge at least one communicating channel for supplying the cooling or lubricating medium, which communicates with the distribution channel. A groove is connected to the communicating channel on the major and/or minor flank. The face may be provided with at least one additional channel for supplying the cooling and/or lubricating medium.

EP 1897642T3 patent file describes a disc-shaped milling tool with a central bore for inserting a central pin sealed with a movable sealing. The mid-length part of the central pin is splined and the pin is inserted in the tool body which is provided with individual slots. This invention enables flow control of the fluid through channels directed at the face of the cutting part of the cutting tool. It uses the option of fitting the component in question in the space between the inner cavity of the milling cutter and its clamping part, as in the present invention. It can be used for tools with multiple exchangeable cutting inserts arranged in the direction of the tool axis as well as for stepped tools. This invention, however, does not enable the fluid to be supplied to the flank of the cutting part.

Patent file no. DE 102004055377 describes a tool which is provided with a distribution system comprising cooling or lubrication channels of various cross-sections communicating with the means of coolant supply.

The arrangement known from patent file no. EP 1897642 involves a disc-shaped milling tool in which cooling of cutting inserts is provided with the use of two and more structural parts of the entire cutting tool, where individual discs contain channels and attachment plates for the supply of the fluid to the cut.

These solutions are very costly to manufacture and maintain. In addition, the tool must be modified in an irreversible manner when such solutions are applied.

Disclosure of Invention

The invention concerns a rotary tool with inner cooling which consists of holders of cutting inserts. These holders project from the rotary tool. The rotary tool body is adapted for being clamped onto a carrier disc which is adapted for being attached to a machine-tool spindle which is provided with a cutting fluid supply inlet. The rotary tool is adapted for being attached by means of an axial screw to the carrier disc of a machine tool. Interposed between the rotary tool body and the axial screw there is a cup-like threaded bushing; on the face of the rotary tool body, a cap is affixed which has holes that are directed at the cutting inserts. The thread of the cap corresponds to the thread of the bushing.

Preferably, the axial screw is provided with an axial hole which communicates with the cavity in the cap.

It is also preferred when the inner shoulder of the cup-like bushing is provided with recesses which correspond to the recesses on the outer diameter of the horseshoe washer which is placed between the head of the axial screw and the inner shoulder of the cup-like bushing. This enables the supply of the cutting fluid to be variably controlled with respect to the configuration of the horseshoe washer and the cup-like bushing.

Description of figures

Fig. 1 is an isometric view of a milling tool. Fig. 2 is a cross- sectional view of a milling cutter with an axial hole. Fig. 3 shows selected parts of a milling cutter with a screw with an axial hole. Fig. 4 is a cross- sectional view of a milling cutter with a solid screw. Fig. 5 shows selected parts of the milling cutter with a solid screw.

Example embodiments

Example 1

A milling cutter with internal cooling consists of holders 2 of cutting inserts 3, where the holders 2 project from the body T of the milling cutter. The body T of the milling cutter is adapted for being attached to a carrier disc The carrier disc 1 is adapted for being clamped onto the spindle of a machine tool and is also provided with a cutting fluid supply inlet 11 The body T of the milling cutter is attached by means of axial screw 4 to the carrier disc 1 of a milling machine. Between the body T of the milling cutter and the axial screw 4 there is a cup-like bushing 5. The cup-like bushing 5 is provided with a thread. Attached to the face of the body T of the milling cutter there is a cap 6. The cap 6 is provided with holes 62, which are directed at cutting inserts 3, where the thread 63 of the cap 6 corresponds to the thread of the cup-like bushing 5. The axial screw 4 is provided with an axial hole 41 which communicates with the cavity 53 in the cap 6.

Through the supply inlet 1_1 provided in the carrier disc 1 which is clamped onto the spindle of a machine tool, the cutting fluid is supplied via the axial hole 4 in the axial screw 4 fitted through the cup-like bushing to the cavity 53 in the cap 6, where the holes 62 are used to supply it to the cutting inserts 3.

Example 2

A milling cutter with internal cooling consists of holders 2 of cutting inserts 3, where these holders 2 project from the body T of the milling cutter. The body T of the milling cutter is adapted for being attached to a carrier disc 1 The carrier disc 1 is adapted for being clamped onto the spindle of a machine tool and is also provided with a non-axial cutting fluid supply inlet VV. The body T of the milling cutter is attached by means of an axial screw 4 to the carrier disc 1 of a milling machine. Between the body T of the milling cutter and the axial screw 4 there is a cup-like bushing 5. The cup-like bushing 5 is provided with a thread. Attached to the face of the body T of the milling cutter there is a cap 6. The cap 6 is provided with holes 62, which are directed at cutting inserts 3, where the thread 63 of the cap 6 corresponds to the thread of the cuplike bushing 5. The inner shoulder 51 of the cup-like bushing 5 is provided with recesses 52 which correspond to the recesses 71 on the outer diameter of the horseshoe washer 7 which is placed between the head of the axial screw 4 and the inner shoulder 5 of the cup-like bushing 5.

Through the non-axial cutting fluid inlet I in the carrier disc 1 clamped onto the spindle of a machine tool, the cutting fluid is delivered via holes located away from the axis of the milling cutter to the space of the cavity 53 in the cap 6, where holes 62 serve for delivering it to the cutting inserts 3. By loosening and retightening the axial screw 4± one can adjust the flow of the cutting fluid through the recesses 7Λ on the outer diameter of the horseshoe washer 7 and then the recesses 52 in the inner shoulder of the cup-like bushing 5 to the space of the cavity 53 in cap 6.

Industrial utility

The tool described in this invention finds use predominantly in rotational chip cutting of predominantly difficult-to-machine materials, predominantly in milling.