Cutting tool with nozzle

Abstract

To provide a rotating or rotatable hole making tool for internal machining, such as boring or reaming tools, with an improved more reliable shield.SOLUTION: A cutting tool includes a rear end and a front end, with a longitudinal center axis extending from the front end to the rear end. The cutting tool further includes at least one chip-forming cutting edge for machining the workpiece, and a liquid supply conduit extending from the rear end to a nozzle rearward of the front working zone. The nozzle includes an inlet in fluid connection with the liquid supply conduit, and the nozzle includes an outlet. The nozzle has a closed overall shape with an outer circumference that is larger than that of the radial location of the at least one cutting edge.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cutting tool according to the preamble of claim 1, in particular to a rotating or rotatable drilling tool for internal machining, such as a drilling or reaming tool. [Background technology]

[0002] A cutting tool contains a cutting edge for machining a workpiece. Such cutting tools may be stationary, meaning they do not rotate, or they may be rotating or rotatable, meaning they are rotated or can be rotated during machining. Rotary or rotatable cutting tools may be drilling tools, reaming tools, or milling tools. A subcategory of cutting tools is drilling tools, which can be used to create or enlarge holes (also called bores). Generally, reaming tools and drilling tools are similar, but reaming tools are used to create the final surface of a workpiece with very high tolerances. This is also called finishing.

[0003] In some cases, machining is performed on only one section of a workpiece, for example, when a drilling or reaming tool is used to enlarge one bore in the workpiece. In other cases, the front end of the cutting tool can machine a smaller bore at the same time as a cutting insert positioned axially rearward of the radially wider section of the cutting tool machines a wider bore on the same workpiece. In this way, two operations can be performed simultaneously.

[0004] A cutting tool of the type described above may be for machining a housing for an electric motor and may have three sets of cutting edges for machining three coaxial bores in the workpiece, as shown, for example, in EP 3953085. A protective shield is used to prevent chips from one set of cutting edges from interfering with and / or damaging the surface of another set of inserts. This can be particularly useful when the workpiece is made 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] A problem with known solutions is that the shield itself can damage the workpiece or cause friction against the workpiece. Another problem with known solutions is that the shield is heavy, can wear or be damaged, and must maintain a seal against the workpiece to prevent the tip from getting stuck between the shield and the workpiece.

[0006] Object of the invention An object with the present invention is to overcome the drawbacks of known solutions and to provide an improved and more reliable shield. Summary of the Invention

[0007] According to the present invention, the above-mentioned object is achieved by a cutting tool having the features defined in claim 1.

[0008] A cutting tool according to the present invention has a rear end and a front end, with a longitudinal center axis extending from the front end to the rear end. The cutting tool further includes at least one chip-forming cutting edge for machining a workpiece and a liquid supply conduit extending from the rear end to a nozzle rearward of the front working zone, the nozzle having an inlet fluidly connected to the liquid supply conduit and an outlet. The nozzle has a closed overall shape, e.g., annular or circular, with an outer periphery greater than the radial position of at least one cutting edge. The nozzle outlet according to the present invention is configured such that when liquid is supplied through the liquid supply conduit, liquid ejected from the outlet forms a liquid barrier to prevent chips formed during machining from escaping through the barrier.

[0009] The cutting tool further comprises a longitudinal central axis extending from the rear end to the front end. The aforementioned rear end and front end constitute the longitudinal extent of the cutting tool. In this context, rear or rear refers to a point on the cutting tool that is closer to the rear end. Thus, front or front means relatively closer to the front end. The rear end is configured to mount to a machine tool spindle or machine tool interface, such as a tool holder. The rear end can include an interface adapted for mounting to an equivalent machine tool interface, such as a Capto or HSK.

[0010] The front end includes at least one chip-forming cutting edge, which may be in the form of a replaceable cutting insert removably clamped in an insert seat in the front end.

[0011] The liquid supply conduit extends from the rear end to a nozzle aft of at least one cutting edge. The liquid supply conduit in the cutting tool is for directing liquid from the machine tool through the tool toward the nozzle. The nozzle includes an inlet in fluid communication with the liquid supply conduit such that liquid is transferred from the liquid supply conduit through the nozzle inlet to the nozzle. The nozzle further includes an outlet.

[0012] The nozzle extends around the circumference of the tool axially aft of the leading edge and thus has a closed shape. Its outer periphery or perimeter is located outside at least one cutting edge of the leading edge so that the outlet is located radially outside at least one cutting edge. In other words, the perpendicular distance from the longitudinal center axis to the nozzle outlet is greater than the perpendicular distance from the longitudinal center axis to the cutting edge.

[0013] The nozzle is configured such that liquid is supplied at a pressure of, for example, 50 to 150 bar through a liquid supply conduit to a nozzle inlet, through the nozzle and out through an outlet, the ejected liquid forming a liquid barrier to prevent chips formed during machining from escaping through the barrier and thus preventing the chips from damaging the bore surface of the workpiece or interfering with other cutting edges.

[0014] The closed geometry of the nozzle and nozzle outlet creates a barrier that completely encloses at least one cutting, i.e., a cylindrical or conical barrier around at least one cutting insert at the leading end.

[0015] This is particularly advantageous when the workpiece consists of two different materials with different hardness, and the harder material is machined by the cutting insert at the front end, effectively preventing the tip from damaging the section of the workpiece made of the softer material.

[0016] The liquid barrier is less susceptible to wear, damage or displacement, and therefore provides effective protection while advantageously avoiding the problems associated with known solutions.

[0017] According to one embodiment of the present invention, the nozzle may be detachable from the cutting tool. The nozzle can then be attached to the cutting tool such that the liquid inlet of the nozzle is aligned with the liquid supply conduit of the cutting tool. The nozzle thus surrounds the cutting tool at the mounted or fixed location where the liquid source exits the cutting tool and achieves such a fluid connection. According to one embodiment of the present invention, the nozzle may be annular, circular, or ring-shaped and may be attached to a cutting tool having a circular periphery. The nozzle may also be another shape to match the periphery of a section of the cutting tool at a specific axial location.

[0018] Fastening can be accomplished by threads through the nozzle to the cutting tool body or by equivalent means. A removable nozzle is advantageous because it allows the nozzle to be replaced so that a nozzle with a different type of outlet can be installed instead. The different type of outlet may be larger to form a thicker barrier or may be at a different angle relative to the longitudinal center axis. It may also be advantageous to be able to move the nozzle to different axial positions on the tool. At any unused nozzle position, the liquid supply conduit must be blocked or sealed.

[0019] According to one embodiment of the present invention, the nozzle includes multiple spaced inlets. Better liquid flow can then be achieved. The spaced inlets on the nozzle may be configured to align with corresponding liquid supply outlets on the cutting tool.

[0020] According to one embodiment of the present invention, the nozzle can have one continuous outlet extending around the entire circumference of the nozzle, such as an annular slit around the nozzle. Alternatively, the nozzle can have multiple spaced outlets. In this way, the characteristics of the liquid barrier can be tailored to suit the type of chip being created in a particular type of machining process, while allowing for the possibility of controlling the liquid flow rate. In this way, only the flow rate necessary to create the barrier for a particular type of chip is used, thus reducing consumption. The distance between the spaced outlets may have to be adjusted to achieve the liquid barrier and depends on the size of the individual outlets. Even if the liquid barrier is not continuous, i.e., interrupted, the liquid flows from multiple outlets can be close enough to each other so that chips cannot escape through it. Factors that can affect this include, for example, the length of the chip, because as a long chip grows, it first breaks the barrier, but as it grows longer, it is pushed back by the liquid. Nevertheless, it remains separate from the rest of the workpiece and can cause damage.

[0021] In one embodiment of the present invention, the cutting tool includes a second set of cutting edges axially rearward of the leading edge cutting edges. This is advantageous because it allows two separate sections of the workpiece to be machined in the same machining process. Generally, this means that the leading edge cutting edges machine a smaller diameter bore, while the second set of inserts machine a larger, coaxial bore longitudinally behind the leading edge. In this way, two coaxial bores are machined without a tool change. For clarity, it may be useful to refer to the outer and inner sections of the workpiece, the inner section being the one machined by the leading edge of the cutting tool.

[0022] The liquid barrier is particularly advantageous when the tool includes a second set of inserts, especially when the front set machines a harder material than the material machined by the second set of inserts, as chips from the front set of inserts could otherwise interfere with the second set of inserts and damage the cutting edges or the workpiece. The harder material machined by the front set of cutting inserts may be steel, and the softer material machined by the second set of inserts may be aluminum.

[0023] In one embodiment of the present invention, the nozzle may include a secondary outlet that is directed toward the cutting insert to provide cleaning and cooling of the cutting insert or to assist in chip breaking in the cutting process.

[0024] In one embodiment of the present invention, the nozzle may include secondary outlets directed toward the rearward end of the cutting tool. These secondary outlets may be directed rearward at an angle relative to the longitudinal central axis so that the liquid flow is directed partially rearward and partially toward the inner wall of the bore being machined. In this manner, liquid ejected from these secondary outlets can help flush bore chips out of the workpiece so that they do not accumulate therein.

[0025] In one embodiment of the present invention, the nozzle may include secondary outlets directed towards both the cutting insert and the aft end of the tool, as previously described.

[0026] In one embodiment of the present invention, the cutting tool may be used to machine an electric motor housing. The housing may be made of two different materials, for example, the bearing bore may be in a portion of the housing made of, for example, steel, and the stator bore may be in a portion made of, for example, aluminum.

[0027] Electric motor housings and other components can be made from alloys that produce very long chips, placing high demands on the chip controlling properties of the cutting inserts used. The present invention alleviates this as the chip can also be controlled by the liquid barrier.

[0028] In one embodiment of the present invention, regardless of the configuration of the outlets described above in the various embodiments, the liquid supply conduit may be the same as that used in cutting tools with a regular coolant supply that may be supplied with standard coolant liquid from a machine tool.

[0029] According to one embodiment of the present invention, the nozzle is preferably made of metal, such as steel or aluminum.

[0030] According to one embodiment of the present invention, the nozzle is manufactured by an additive manufacturing process such as laser powder bed fusion or binder jetting.

[0031] According to one embodiment, the nozzle is an integral part of the cutting tool.

[0032] Embodiments of the invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a perspective view of a rotating cutting tool according to one embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional view of the rotating cutting tool of FIG. 1. [Figure 3a] 1 shows a diagram of a nozzle according to one embodiment. [Figure 3b] 1 shows a diagram of a nozzle according to one embodiment. [Figure 3c] 1 shows a diagram of a nozzle according to one embodiment. [Figure 4] 1 is a cross-sectional view of one embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view of the nozzle of the embodiment of FIG. [Figure 6a]FIG. 1 is a perspective view of a rotating cutting tool according to one embodiment with the liquid barrier turned off. [Figure 6b] FIG. 1 is a perspective view of a rotating cutting tool with the liquid barrier turned on, according to one embodiment. [Figure 7a] 1A-1D show cross-sectional views of a workpiece with a rotating cutting tool according to one embodiment at different stages of performing a cutting operation on the workpiece. [Figure 7b] 1A-1D show cross-sectional views of a workpiece with a rotating cutting tool according to one embodiment at different stages of performing a cutting operation on the workpiece. [Figure 7c] 7b and 7c show cross-sectional views of a workpiece with a rotating cutting tool according to an embodiment at different stages of performing a cutting operation on the workpiece, with the liquid barrier activated; DETAILED DESCRIPTION OF THE INVENTION

[0034] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

[0035] In one embodiment of the present invention, the cutting tool (1) seen in FIG. 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) having 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 inserts, and the cutting tool further 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 fluidly connected to the cutting tool's liquid supply conduit (5) and is attached to the nozzle with a screw that extends into the cutting tool through a threaded hole (11). Thus, liquid can flow from the cutting tool's liquid supply conduit to the nozzle inlet without leakage.

[0036] The outer periphery of the annular nozzle is positioned radially outside the cutting insert, and the annular outlet has a circumference located radially outside the cutting insert, as seen in FIG. 2. The annular outlet (8) is configured as a slit in the nozzle, and when liquid is supplied to the nozzle inlet through the liquid supply, the liquid proceeds through the nozzle to the outlet. When the liquid is ejected from the outlet (8), it forms a liquid barrier (9), as seen in FIGS. 3, 4, 6b, 7b, and 7c. Thus, the outlet slit (8) is wide enough to form a barrier strong enough to prevent cutting chips from escaping through the outlet slot, but narrow enough that the barrier remains uninterrupted around the outlet at a given pressure. This outlet configuration can be determined by those skilled in the art by taking into account the type of chips to be prevented from escaping and the capacity of the liquid supply conduit, e.g., flow rate and pressure.

[0037] According to an embodiment, the nozzle is detachable from the cutting tool, as seen in Figures 3a and 3b. This is achieved by means of screws and threaded holes (11) for attachment to the cutting tool, as previously described. Changing the nozzle can be advantageous if the tool is moved to a different machine tool having a different capacity for dispensing liquid, or if the nozzle is changed to a type according to another embodiment of the invention to provide additional features, as seen in Figure 5.

[0038] The nozzle of this embodiment comprises a plurality of spaced inlets in fluid communication with corresponding holes in the cutting tool through which the liquid supply conduits exit and from which the liquid is supplied, the number of inlets and their size being dependent on the flow rate and pressure required to achieve the liquid barrier and provided by the machine tool, which can be adjusted accordingly.

[0039] According to this embodiment of the invention, the nozzle is annular due to the fact that the reaming tool of the embodiment is a rotating or rotatable tool having a circular axial cross section. When the tool is assembled, the nozzle is attached to the cutting tool on the section of the cutting tool rearward of the cutting insert at the front end, as seen in Figures 2 and 3a-3c, with the outer periphery of the cutting tool and the inner periphery of the nozzle having corresponding diameters, as described above.

[0040] The cutting tool of this embodiment described herein includes a second set of cutting inserts. Because 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, i.e., an inner section machined by the leading end of the cutting tool, and a wider outer section machined by the aforementioned second set of inserts. As seen in Figures 7a-7c, the cutting tool starts in a position completely outside the workpiece. As the cutting process begins, the cutting tool enters the workpiece and begins machining the wider section when the second set of inserts contact the workpiece (Figure 7a). As the machining process progresses (Figure 7b), the leading end cutting inserts contact the inner section of the workpiece, where a smaller diameter is machined (Figure 7c). In this embodiment, this section is made of a material that creates a longer chip that risks damaging other parts of the workpiece. When the inner portion is machined, the liquid barrier prevents the formed chips from escaping and damaging the workpiece.

[0041] In an embodiment of the present invention, the cutting tool liquid supply conduit is connected to the normal coolant liquid supply conduit of the machine tool. Using another embodiment of the nozzle, the nozzle can have an outlet directed towards the chip formation area, thereby achieving normal cooling and chip breaking capabilities.

Claims

1. 1. A cutting tool for machining a workpiece, comprising: a rear end and a front end, a rear end and a front end, the front end including at least one chip-forming cutting edge for cutting a section of the workpiece; a central longitudinal axis extending from the rear end to the front end; a liquid supply conduit extending from the rear end of the cutting tool to a nozzle aft of at least one cutting edge; the nozzle having an inlet in fluid communication with the liquid supply conduit; a liquid supply conduit, the nozzle having an outlet; the nozzle has a closed shape with the nozzle periphery and the outlet positioned radially outward of the at least one cutting edge; 1. A cutting tool, comprising: a nozzle outlet 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 of claim 1 , wherein the nozzle is detachable from the cutting tool.

3. The cutting tool of claim 1 , wherein the nozzle is annular.

4. The cutting tool of claim 1 , wherein the nozzle comprises a plurality of spaced inlets.

5. The cutting tool of claim 1 , wherein the outlet is formed as an annular slit in the nozzle.

6. The cutting tool of claim 1 , wherein the nozzle comprises a plurality of spaced apart outlets.

7. The cutting tool of claim 1 , comprising at least one additional chip-forming cutting edge located axially rearward and radially outward of the cutting edge at the leading end.

8. The cutting tool of claim 1 , wherein the cutting tool is a rotating cutting tool.

9. The cutting tool of claim 1 , wherein the cutting tool is a reaming tool.

10. The cutting tool of claim 1 , wherein the liquid supply conduit is a coolant liquid supply conduit.

11. The cutting tool of claim 1 , wherein the nozzle comprises a secondary outlet directed toward the cutting insert for chip breaking and cooling.

12. The cutting tool of claim 1 , wherein the nozzle includes a rearwardly directed secondary outlet for flushing chips from the workpiece.

13. The cutting tool of claim 1 , wherein the cutting tool is a milling tool.

14. A nozzle for use with a cutting tool according to any one of claims 1 to 13.

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