Cutting tool with nozzle

Abstract

Provided is a cutting tool with a nozzle. A cutting tool according to the present invention includes a trailing end and a leading end, and a longitudinal central axis extending from the leading end to the trailing end. The cutting tool further includes: at least one chip-forming cutting edge for machining a workpiece; a liquid supply conduit extending from the aft end to a nozzle located aft of the forward working area, where the nozzle includes an inlet in fluid connection with the liquid supply conduit, and where the nozzle includes an outlet. The nozzle has a closed unitary shape, the outer periphery of which is larger than the radial position of the at least one cutting edge. The outlet of the nozzle according to the present invention is configured such that when liquid is supplied through the liquid supply conduit, the liquid ejected from the outlet forms a liquid barrier to prevent cuttings formed during machining from escaping through the barrier.

Description

Technical Field

[0001] The invention relates to a cutting tool according to the preamble of claim 1 , in particular to a rotary or rotatable hole machining tool for internal machining, such as a boring tool or a reaming tool. Background Art

[0002] Cutting tools contain cutting edges that are used to machine a workpiece. These cutting tools can be stationary, meaning they do not rotate, or they can be rotary or rotatable, meaning they are rotated or can be rotated during the machining process. Rotary or rotatable cutting tools can be boring tools, reaming tools, or milling tools. A subcategory of cutting tools is holemaking tools, which are used to create or enlarge holes (also called boreholes). Generally speaking, reaming tools and boring tools are similar, but reaming tools are used to create a final surface on a workpiece with very high tolerances. This is also known as finishing.

[0003] In some cases, machining occurs on only one section of the workpiece, such as when a boring or reaming tool is used to enlarge a hole in a workpiece. In other cases, the front end of the cutting tool can machine a small hole while a cutting insert, located axially to the rear on the radially wider section of the cutting tool, simultaneously machines a wider hole in the same workpiece. In this way, two operations can be performed simultaneously.

[0004] Cutting tools of the type described above can be used to machine electric motor housings and may include three sets of cutting edges for machining three coaxial bores in a workpiece, as shown, for example, in EP 3 953 085 B1. A protective shield may be used to prevent chips generated by one set of cutting edges from interfering with the other set of blades and / or damaging the surface. This can be particularly beneficial when the workpiece is composed of several different materials, and chips from a harder material (such as steel) could damage the surface of a softer material (such as aluminum).

[0005] One problem with existing solutions is that the shield itself can damage or cause friction with the workpiece. Another problem with existing solutions is that the shield is heavy, can wear or become damaged, and must maintain a tight seal with the workpiece to prevent chips from becoming trapped between the shield and the workpiece. Summary of the Invention

[0006] Purpose of the Invention

[0007] An object of the present invention is to overcome the disadvantages of existing solutions and to provide an improved and more reliable protective cover. SUMMARY OF THE INVENTION

[0009] According to the invention, this object is achieved by means of a cutting tool having the features defined in claim 1 .

[0010] The cutting tool according to the present invention comprises a rear end and a front end, and a longitudinal center axis extending from the front end to the rear end. The cutting tool also comprises: at least one chip-forming cutting edge for machining a workpiece; a liquid supply conduit extending from the rear end to a nozzle located behind the front working area, wherein the nozzle comprises an inlet fluidically connected to the liquid supply conduit, and wherein the nozzle comprises an outlet. The nozzle has a closed overall shape, such as an annular or circular shape, and its outer circumference is larger than the radial position of the at least one cutting edge. The outlet of the nozzle according to the present invention is configured so that when liquid is supplied through the liquid supply conduit, the liquid ejected from the outlet forms a liquid barrier to prevent chips formed during machining from escaping through the barrier.

[0011] The cutting tool also includes a longitudinal center axis extending from the front end to the rear end. The rear end and the front end constitute the longitudinal extent of the cutting tool. In this context, "rear" or "behind" refers to a point on the cutting tool closer to the rear end. "Front" or "in front of" means relatively closer to the front end. The rear end is configured to be mounted in a machine tool spindle or a machine tool interface, such as a tool holder. The rear end may include an interface suitable for mounting in an equivalent machine tool interface, such as Capto or HSK.

[0012] The front end comprises at least one chip-forming cutting edge. These cutting edges can be in the form of replaceable cutting inserts, which are detachably clamped in an insert seat located at the front end.

[0013] A liquid supply conduit extends from the rear end to a nozzle located behind the at least one cutting edge. The liquid supply conduit within the cutting tool is configured to direct liquid from the machine tool, through the tool, and toward the nozzle. The nozzle includes an inlet fluidically or liquid-connected to the liquid supply conduit such that liquid is transferred from the liquid supply conduit through the nozzle inlet to the nozzle. The nozzle also includes an outlet.

[0014] The nozzle extends around the circumference of the tool, axially rearward of the front cutting edge, and thus has a closed shape. The outer periphery or edge of the nozzle is located outboard of the at least one cutting edge at the front end, such that the nozzle outlet is located radially outward of the at least one cutting edge. In other words, the vertical distance from the longitudinal center axis to the nozzle outlet is greater than the vertical distance from the longitudinal center axis to the cutting edge.

[0015] The nozzle is configured so that when liquid is supplied to the nozzle inlet through the liquid supply conduit at a pressure of, for example, 50-150 bar, passes through the nozzle, and exits from the outlet, the sprayed liquid forms a liquid barrier to prevent chips formed during the machining process from escaping through the barrier, thereby preventing the chips from damaging the channel surface of the workpiece or interfering with other cutting edges.

[0016] The closed shape of the nozzle and the nozzle outlet form a barrier which completely encloses the at least one cutting edge, ie forms a cylindrical or conical barrier around the at least one cutting insert at the front end.

[0017] This design is particularly advantageous when the workpiece is composed of two different materials of different hardness, and the harder material is processed by the cutting insert at the front end. It can effectively prevent chips from damaging the section of the workpiece made of the softer material.

[0018] The liquid barrier provides effective protection while avoiding problems associated with existing solutions as it is not susceptible to wear, damage or dislocation.

[0019] According to one embodiment of the present invention, the nozzle can be attachable to the cutting tool and detachable from the cutting tool. Thus, the nozzle can be attached to the cutting tool so that the liquid inlet of the nozzle is aligned with the liquid supply conduit of the cutting tool. The nozzle thus encloses the cutting tool at a position where the liquid supply leaves the cutting tool and is attached or fastened to achieve a fluid connection. According to one embodiment of the present invention, the nozzle can be annular, circular or ring-shaped and can be attached to a cutting tool with a circular outer circumference. The nozzle can also be another shape to match the outer circumference of a section of the cutting tool at a specific axial position.

[0020] The fastening can be achieved by passing a screw through the nozzle into the cutting tool body or by equivalent means. An attachable / detachable nozzle has an advantage because it allows the nozzle to be replaced so that nozzles with different types of outlets can be assembled alternatively. Another type of outlet can be one in which the outlet is larger to create a thicker barrier, or it can be an outlet with different angles relative to the longitudinal center axis. It can also be advantageous to be able to move the nozzle to different axial positions of the tool. Thus, at any unused nozzle position, the liquid supply conduit will have to be plugged or blocked.

[0021] According to one embodiment of the present invention, the nozzle may include a plurality of spaced-apart inlets. In this way, better liquid flow may be achieved. The spaced-apart inlets on the nozzle may be configured to align with matching liquid supply outlets on the cutting tool.

[0022] According to one embodiment of the present invention, the nozzle may include a single continuous outlet extending around the entire circumference of the nozzle, such as an annular slit surrounding the nozzle. Alternatively, the nozzle may include multiple spaced-apart outlets. This allows the characteristics of the liquid barrier to be tailored to the type of chip generated in a particular machining process, while also allowing for control of the liquid flow rate. This way, only the flow rate required to create a barrier tailored to the specific chip type is used, thereby reducing consumption. The distance between the spaced-apart outlets may need to be adjusted to achieve the liquid barrier, and this will depend on the size of the individual outlets. Even if the liquid barrier is not continuous, i.e., uninterrupted, the liquid streams from the multiple outlets can be kept close enough to each other that chips cannot escape through them. For example, one factor that can influence this effect is chip length, as long chips may initially break through the barrier as they grow, but as they become longer, the liquid pushes them back. Despite this, it remains away from the rest of the workpiece, where it could cause damage.

[0023] In one embodiment of the present invention, the cutting tool includes a second set of cutting edges located axially to the rear of the front cutting edge. This is particularly advantageous because two separate sections of the workpiece can be machined in the same machining process. Typically, this means that the front cutting edge machines a smaller diameter bore, while the second set of blades machines a larger, coaxial bore longitudinally to the rear of the front end. This allows two coaxial bores to be machined without changing the tool. For clarity, it can be helpful to refer to an outer section and an inner section of the workpiece, where the inner section is the section machined by the front end of the cutting tool.

[0024] The liquid barrier is particularly advantageous in the case of a tool comprising a second set of blades, since otherwise the chips produced by the first set of blades could interfere with the second set of blades and damage the cutting edge or the workpiece, particularly when the material machined by the first set of blades is harder than that machined by the second set of blades. The harder material machined by the first set of cutting blades may be steel, and the softer material machined by the second set of blades may be aluminum.

[0025] In one embodiment of the present invention, the nozzle may include an auxiliary outlet. The nozzle may include an auxiliary outlet directed toward the cutting insert to provide flushing and cooling of the cutting insert, or to assist in chip breaking during the cutting process.

[0026] In one embodiment of the present invention, the nozzle may include auxiliary outlets directed toward the rear end of the cutting tool. These auxiliary outlets may be directed rearward at an angle relative to the longitudinal center axis, such that the liquid stream is directed partially rearward and partially toward the inner wall of the machined channel. In this manner, the liquid ejected from these auxiliary outlets can help flush chips from the channel, thereby flushing the chips away from the workpiece and removing them from the workpiece, preventing them from accumulating internally.

[0027] In one embodiment of the invention, the nozzle may comprise auxiliary outlets directed both towards the cutting insert and towards the rear end of the tool, as previously described.

[0028] In one embodiment of the present invention, the cutting tool can be used to machine an electric motor housing. The housing can be made of two different materials, wherein, for example, the bearing bore can be located in a portion of the housing made of, for example, steel, and, for example, the stator bore can be located in a portion made of, for example, aluminum.

[0029] Electric motor housings and other components may be made of alloys that produce very long chips, which places high demands on the chip control properties of the cutting inserts used. The present invention alleviates this problem because the chips can also be controlled by the liquid barrier.

[0030] In one embodiment of the present invention, regardless of the outlet configuration previously described in the various embodiments, the liquid supply conduit may be the same as used in cutting tools having a conventional coolant supply, ie, standard coolant liquid may be delivered thereto from the machine tool.

[0031] According to one embodiment of the present invention, the nozzle is preferably made of metal, such as steel or aluminum.

[0032] According to one embodiment of the present invention, the nozzle may be manufactured by an additive manufacturing process, such as a laser powder bed fusion process or a binder jetting process.

[0033] According to one embodiment of the invention, the nozzle is an integral part of the cutting tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The following is a detailed description of the embodiments of the present invention cited as examples with reference to the accompanying drawings. In the accompanying drawings:

[0035] Figure 1 is a perspective view of a rotary cutting tool according to one embodiment of the present invention,

[0036] Figure 2 yes Figure 1 Cross-sectional view of a rotary cutting tool,

[0037] Figures 3a to 3care multiple views of a nozzle in one embodiment,

[0038] Figure 4 is a cross-sectional view of an embodiment of the present invention,

[0039] Figure 5 yes Figure 4 A cross-sectional view of the nozzle in the embodiment shown,

[0040] Figures 6a to 6b is a perspective view of a rotary cutting tool according to one embodiment with the liquid barrier closed (6a) and open (6b),

[0041] Figures 7a to 7c are three cross-sectional views of a workpiece with a rotary cutting tool according to one embodiment at different stages of a cutting operation in the workpiece. Figure 7b and 7c In the experiment, the liquid barrier is activated. DETAILED DESCRIPTION

[0042] Now, with reference to the accompanying drawings, embodiments of the present invention will be described in detail.

[0043] According to one embodiment of the present invention, Figure 1 As shown, the cutting tool (1) is a reaming tool for machining an electric motor housing (12). The cutting tool includes a rear end (2) and a front end (3), and a central rotation axis (L) extending from the rear end to the front end. The front end includes a plurality of cutting edges (4) in the form of replaceable cutting blades; and the cutting tool also includes a liquid supply conduit (5) extending from the rear end to an annular nozzle (6). The nozzle includes a plurality of inlets (7) and an annular, uninterrupted outlet (8) formed as an annular slit in the nozzle. The nozzle is fluidically connected to the liquid supply conduit (5) of the cutting tool and is attached to the cutting tool by a screw extending through a screw hole (11) into the cutting tool. Therefore, liquid can flow from the liquid supply conduit of the cutting tool into the nozzle inlet without leakage.

[0044] The outer periphery of the annular nozzle is located radially outside the cutting blade, and the periphery of the annular outlet is located radially outside the cutting blade, as in Figure 2As can be observed in . The annular outlet (8) is constructed as a slit in the nozzle, and when liquid is supplied through the liquid supply conduit and enters the nozzle inlet, the liquid reaches the outlet through the nozzle. When the liquid is ejected from the outlet (8), it forms a liquid barrier (9), as can be observed in Figures 3, 4, 6b, 7b and 7c. The outlet slit (8) is therefore wide enough to allow the liquid to form a barrier strong enough to prevent chips from escaping through the barrier, but the outlet slit (8) is narrow enough so that the barrier remains uninterrupted around the outlet at a given pressure. This outlet configuration is made by the skilled person according to the type of chips to be prevented from escaping and according to the capabilities of the liquid supply conduit (such as flow rate and pressure).

[0045] According to this embodiment, as in Figure 3a and 3b As can be seen in FIG, the nozzle can be attached to the cutting tool and can be detached from the cutting tool. As previously described, this is achieved by means of a screw and screw hole (11) for attaching the nozzle to the cutting tool. If the tool is moved to a different machine tool having another liquid supply capability, or if the nozzle is replaced with a type according to another embodiment of the present invention to provide additional features, such as Figure 5 As shown, it may be advantageous to replace the nozzle.

[0046] In this embodiment, the nozzle includes a plurality of spaced-apart inlets that are fluidly connected to corresponding holes in the cutting tool where the liquid supply conduit exits and to corresponding holes where the liquid is supplied. The number of inlets and their sizes will depend on the flow rate and pressure required to achieve the liquid barrier, which are provided by the machine tool and can be adjusted accordingly.

[0047] According to this embodiment of the invention, the nozzle is annular because the reaming tool in this embodiment is a rotary or rotatable tool with a circular axial cross-section. When the tool is assembled, as previously described, the nozzle is attached to the cutting tool at a section of the cutting tool where the outer periphery of the cutting tool and the inner periphery of the nozzle have corresponding diameters and which is located behind the cutting blade at the front end, as shown in FIG. Figure 2 、 3a -As seen in 3c.

[0048] The cutting tool of the embodiment described herein includes a second set of cutting blades. Since the cutting tool is a reaming tool for machining an electric motor housing, two different sections and diameters of the workpiece are machined in the same operation. The workpiece has an inner section, which is the section machined by the front end of the cutting tool, and a wider outer section, which is machined by the second set of blades. As shown in Figures 7a to 7cIt can be observed that the cutting tool starts from a position where the cutting tool is completely outside the workpiece. As the cutting process begins, the cutting tool enters the workpiece and begins to machine the wider section ( Figure 7a As the cutting process progresses ( Figure 7b ), the front cutting blade comes into contact with the inner section of the workpiece, where the smaller diameter ( Figure 7c ). In this embodiment, this section is made of a material that produces longer chips, which can bring the risk of damaging other sections of the workpiece. When machining this inner part, the liquid barrier prevents the chips formed from escaping and causing damage to the workpiece.

[0049] In this embodiment of the invention, the liquid supply conduit of the cutting tool is connected to the conventional coolant liquid supply conduit of the machine tool. By using the nozzle according to another embodiment, conventional cooling and chip breaking functions can be achieved, since the nozzle can thereby have an outlet directed towards the chip formation area.

Claims

1. A cutting tool for machining a workpiece, comprising: - backend and frontend, - wherein the front end comprises at least one chip-forming cutting edge for cutting a section of a workpiece, - a longitudinal centre axis extending from said rear end to said front end, a liquid supply conduit extending from the rear end of the cutting tool to a nozzle located behind the at least one cutting edge, - wherein the nozzle comprises an inlet, the inlet being in fluid connection with the liquid supply conduit, and - said nozzle comprises an outlet, It is characterized by - the nozzle has a closed shape, wherein the outer periphery of the nozzle and the outlet are located radially outside the at least one cutting edge, and The outlet of the nozzle is configured such that, when liquid is supplied through the liquid supply conduit, the liquid ejected from the outlet forms a liquid barrier to prevent chips formed during machining from escaping through the barrier. 2 . The cutting tool according to claim 1 , wherein the nozzle is attachable to / detachable from the cutting tool.

3. The cutting tool according to any one of claims 1-2, wherein the nozzle is annular.

4. The cutting tool according to any one of claims 1 to 3, wherein the nozzle comprises a plurality of spaced-apart inlets.

5. The cutting tool according to any one of the preceding claims, wherein the outlet is formed as an annular slit in the nozzle.

6. The cutting tool according to any one of claims 1 to 4, wherein the nozzle comprises a plurality of spaced-apart outlets.

7. The cutting tool according to any of the preceding claims, comprising at least one additional chip-forming cutting edge located axially behind and radially outside the cutting edge of the front end.

8. The cutting tool according to any one of the preceding claims, wherein the cutting tool is a rotary cutting tool.

9. The cutting tool according to any one of the preceding claims, wherein the cutting tool is a reaming tool.

10. The cutting tool according to any one of the preceding claims, wherein the liquid supply conduit is a coolant liquid supply conduit.

11. The cutting tool according to any one of the preceding claims, wherein the nozzle comprises an auxiliary outlet directed towards the cutting insert for chip breaking and cooling.

12. The cutting tool according to any one of the preceding claims, wherein the nozzle comprises a rearwardly directed auxiliary outlet for flushing chips away from the workpiece.

13. The cutting tool according to any one of claims 1 to 6, wherein the cutting tool is a milling tool.

14. A nozzle for a cutting tool according to any one of the preceding claims.

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