Knife rest and numerical control machine tool comprising same

Abstract

The tool rest comprises a body (11) extending along an axis A-A, one end of the body comprises a base (12), the other end of the body comprises a head (13) capable of rotating, the base is used for being fastened to the numerical control machine tool (20), and the head comprises at least two spindles (14, 14 ', 14' ') used for holding tools. 14 ', 14' ') each intended to receive a cutting tool (15, 15', 15 '') in an engaged manner, the spindles occupying, depending on the angular position of the head (13), a working position in which they are intended to perform a machining operation on a workpiece held in position in the clamp (21) or a standby position in which they are withdrawn from the workpiece, each spindle being configured to be controlled independently of the other spindles, therefore, the cutting tool carried by the main shaft is fixed or driven to rotate regardless of the position occupied by the main shaft.

Description

Technical Field

[0001] The utility model relates to the field of numerical control machine tools for machining parts, preferably micro - mechanical parts, and to the field of equipment for such machine tools.

[0002] More specifically, the utility model relates to a tool holder comprising a plurality of spindles for holding tools and a numerical control machine tool comprising such a tool holder. Background Art

[0003] Numerical control machine tools are used for mass - producing parts, especially by machining according to the instructions of a computer program. These machine tools include tools mounted on spindles for holding tools and are usually equipped with a tool changer for replacing the tool held by the spindle to adapt it to the machining operation performed on the part held in place in the fixture.

[0004] When changing the tool, the machine tool stops production, which means that the machining operation is interrupted. Therefore, the goal is to minimize the tool change time. To this end, tool changers have been developed to work as much as possible during the shielding time and minimize the machine tool downtime to improve its productivity.

[0005] For example, a multi - axis tool holder is known that includes a head on which several spindles are arranged, one of which is in the working state and the others are in the rest state. Specifically, the working spindle is engaged with the drive mechanism through a coupling system. Therefore, between two machining operations, the tool can be changed by the following operations: disengaging the working spindle (i.e., the spindle carrying the tool to be replaced), rotating the head to present the next spindle, and coupling this spindle to the drive mechanism.

[0006] However, this solution is not entirely satisfactory because, although the tool change time is reduced, the tool change time is not completely shielded. In fact, between each tool change, for this type of multi - axis tool holder, the tool to be replaced must be braked before the tool change and the next tool must be accelerated after it is coupled to the drive mechanism until it reaches its machining speed. These multi - axis tool holders also require a certain amount of time to disengage the tool to be replaced, rotate the head and position the next tool to align it with the coupling system, and then perform the coupling. Due to the coupling system, this solution is also particularly complex and expensive.

[0007] There are also multi - axis tool holders that solve the problems of spindle acceleration and braking, in which all tools are driven to rotate synchronously. Therefore, when changing the tool, the next tool is already driven at its machining speed and can start machining the part. However, these multi - axis tool holders require a large amount of energy to rotate all tools simultaneously. In addition, due to the motion transmission power chain, the maximum rotational speed of the tools they carry is relatively limited.

[0008] Generally speaking, regardless of whether the tools carried by it rotate individually or simultaneously, the multi-axis tool holders of the prior art are very bulky, which generates a large moment of inertia and increases the risk of collision between the fixture and the tools carried by the tool holder.

[0009] In addition to the above disadvantages, these solutions are not suitable for machining micro-mechanical parts. Summary of the Utility Model

[0010] The present utility model solves the above disadvantages by providing a solution that allows the complete masking of the tool change time, especially by masking the tool acceleration and deceleration phases. Another object achieved by the present utility model is to maximize the compactness of the machine tool and reduce the mass of the moving bodies.

[0011] To this end, the present utility model relates to a tool holder that includes a body extending along axis A-A. The body includes a base at one end for fastening to a numerical control machine tool and a rotatable head at the other end. The head includes at least two spindles for holding tools, and each spindle is configured to receive a cutting tool in an engaging manner. Depending on the angular position of the head, the spindles occupy a working position or a standby position. In the working position, they are used to perform machining operations on a workpiece held in place in a fixture, and in the standby position, they are withdrawn from the workpiece. Each spindle is configured to be controlled independently of the other spindles so that the cutting tool carried by it remains stationary or is driven to rotate regardless of the position it occupies.

[0012] Since the spindles are independently servo-controlled, the spindles can be accelerated and decelerated during the masking time. Therefore, the present utility model allows tool changes to be carried out during the dead time, which is reduced to only the duration of the head rotating to the next tool in contact with the workpiece. Due to the features of the present utility model, the tool change time (total tool change time) is estimated to be in the range of tenths of a second.

[0013] The present utility model also has the advantage of being applicable to any existing machine tool.

[0014] In addition, due to the present utility model, the spindles can reach relatively high rotational speeds, for example, in the range of 60,000 to 80,000 revolutions per minute.

[0015] In a specific embodiment, the present utility model may further include one or more of the following features, which can be considered individually or in any technically feasible combination.

[0016] In a specific embodiment, the rotational axis of the head coincides with axis A-A.

[0017] In a specific embodiment, the base is configured such that axis A-A forms an angle between 35 degrees and 55 degrees with respect to the vertical axis.

[0018] These features contribute to maximizing the compactness of the device.

[0019] In a specific embodiment, these spindles are distributed around the axis of rotation of the head, preferably evenly distributed, and each spindle is arranged such that its axis forms an angle between 35 degrees and 55 degrees with respect to the axis A-A, and their axes do not intersect.

[0020] On the one hand, this feature makes it easier to clean the tool when the tool is at rest, so as to avoid or limit the risk of collision with the fixture; on the other hand, it enables all spindles to maintain the same working position, thus contributing to ensuring that the machining tolerances are met.

[0021] In a specific embodiment, these spindles are arranged relative to each other such that the projections of their longitudinal axes in a plane P orthogonal to the axis A-A form a regular n-sided polygon centered on the axis A-A, where n is the number of spindles.

[0022] In a specific embodiment, these spindles are arranged such that the distance between their longitudinal axes and the axis A-A is greater than the radius of the spindle.

[0023] This feature also contributes to cleaning the tool in the rest state, so as to avoid or limit the risk of collision with the fixture.

[0024] In a specific embodiment, each spindle includes its own motor for rotating or holding stationary the cutting tool it carries.

[0025] This feature allows reducing the energy consumption of the tool holder because the spindles that are not performing machining operations do not rotate about their respective longitudinal axes.

[0026] In a specific embodiment, at least one spindle is adapted to occupy at least two different working positions, each working position being defined by a predetermined angular position of the head of the tool holder.

[0027] In a specific embodiment, at least one spindle is adapted to continuously occupy the working position while the head of the tool holder rotates. This arrangement also involves continuous movement of the fixture.

[0028] According to another object, the present utility model relates to a numerically controlled machine tool preferably for machining micro-mechanical parts, which includes at least one tool holder as described above, the tool holder being directly fastened to the machine frame through a base or a carrier capable of translational movement in a vertical plane, such that the axis A-A forms an angle between 35 degrees and 55 degrees with respect to the vertical axis, and the machine tool further includes a fixture for holding the part to be machined in place.

[0029] In a specific embodiment, the machine tool includes two tool holders arranged on both sides of the fixture.

[0030] In a specific embodiment, the machine tool includes a protective wall that prevents chips and cutting fluid from splashing, and the body of the said or each tool holder is joined in a liquid-tight manner in a corresponding opening of the protective wall.

[0031] Another aspect of the present disclosure relates to a method for replacing the cutting tool of a machine tool as described above, wherein:

[0032] - A first cutting tool engaged in the spindle in the working position performs a first machining stage, and a second cutting tool engaged in the spindle in the standby position is used to perform a second machining stage and is prevented from rotating;

[0033] - Before the end of the first machining stage, the second cutting tool rotates about its axis until it reaches the rotational speed characteristic of the second machining stage;

[0034] - Once the first machining stage is completed, the head is pivoted about the axis A-A so as to drive the spindle carrying the second cutting tool into the working position, enabling the second cutting tool to start the second machining stage, and driving the spindle carrying the first cutting tool into the standby position, and once the spindle carrying the first cutting tool reaches its standby position, the first cutting tool is prevented from rotating. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features and advantages of the present utility model will become apparent after reading the following detailed description given as a non-limiting example in reference to the accompanying drawings, wherein:

[0036] - Figure 1 A perspective view of a multi-spindle tool holder according to a preferred embodiment of the present utility model is shown;

[0037] - Figure 2 A view of the tool holder oriented along the longitudinal axis of the tool holder body is shown Figure 1 of the tool holder;

[0038] - Figure 3 A side view of the tool holder is shown Figure 1 of the tool holder;

[0039] - Figure 4 A perspective view of two tool holders arranged on both sides of a workpiece fixture is shown.

[0040] It should be noted that, for clarity, the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0041] Figure 1There is shown a tool holder 10 for machining parts, preferably micromechanical parts. The tool holder 10 includes a body 11 which extends along a longitudinal axis indicated by "axis A-A". In an embodiment of the present invention, the body 11 includes a base 12 at one end and a head 13 at the other end. The base 12 is for fastening to a numerical control machine tool 20, and the head 13 is rotatable about an axis coinciding with axis A-A. The head 13 has at least two spindles 14, 14' or 14" for holding tools, and each spindle is for receiving a cutting tool 15, 15' or 15" in an engaging manner. Depending on the angular position of the head 13, each spindle 14, 14' and 14" occupies a working position or a standby position. In the working position, it is used to perform a machining operation on a workpiece held in place in a fixture 21, and in the standby position, it is withdrawn from the workpiece.

[0042] It should be noted that the tool holder 10 can be translationally driven. For example, in the case where the base 12 is fastened to a carrier (not shown in the figure) of the machine tool 20 that can move along at least one translational degree of freedom, the carrier preferably moves along three translational degrees of freedom in the three reference XYZ directions.

[0043] Alternatively, the tool holder 10 can be stationary. For example, in the case where the base 12 is directly fastened to the frame 22 of the machine tool 20.

[0044] Advantageously, the spindles 14, 14' and 14" are configured to be controlled independently of each other so as to rotate or hold stationary the cutting tools 15, 15' or 15" carried by them. This feature is particularly advantageous when changing tools. Preferably, the spindles 14, 14' and 14" are motorized spindles, also known as "electric spindles", and each spindle includes its own motor for rotating or holding stationary the cutting tool 15, 15' or 15" carried by it.

[0045] In particular, in order to replace the first cutting tool 15 for performing the first machining stage with the second cutting tool 15' for performing the second machining stage, the second cutting tool 15' is rotated until it reaches the rotational speed characteristic of the second machining stage before the end of the first machining stage.

[0046] The first cutting tool 15 is engaged in the spindle 14 in the working position, and the second cutting tool 15' is engaged in the spindle 14' in the standby position.

[0047] Once the first machining phase is complete, the head 13 is pivoted to drive the spindle 14, which is in the working position, to the standby position, and the spindle 14', which is in the standby position, to the working position. Since the second cutting tool 15' has already reached its machining speed while the spindle 14', in which it is engaged, is in the standby position, the second machining phase begins immediately. The spindle 14, carrying the first cutting tool 15, is now in the standby position, and the first cutting tool 15 is stationary.

[0048] Thus, since the second cutting tool 15' is rotating and the first cutting tool 15 is stopped during the hidden time, the cutting tools are changed with a dead time reduced to only the duration of the head rotation.

[0049] Each spindle 14, 14' and 14" extends along a longitudinal axis indicated by axis BB, axis BB' and axis BB", respectively, which also form their axis of rotation. Figure 1 and Figure 3 In the figures, this axis is only shown for the spindle 14 in its working position. As shown in these figures, in the working position, the spindle 14 is oriented so that its axis BB is parallel to the vertical axis. However, in another working position, the spindle 14 can also be oriented so that its axis BB is parallel to the horizontal axis. The spindle 14 can also occupy a dynamic working position, that is, the head 13 can be rotated during the machining operation. In this case, the clamp 21 can be moved and moved according to the instructions related to the machining program, and / or the tool holder 10 can be moved via its base 12 and moved according to the instructions related to the machining program.

[0050] In a preferred embodiment of the present invention, as shown in the figure, the tool holder 10 includes three spindles 14, 14' and 14". In the figure, the distribution of the spindles 14, 14' and 14" on the head 13 of the tool holder 10 is specifically shown. Figure 2 In the embodiment of the present invention, the main shafts 14, 14' and 14" are evenly distributed around the axis of rotation of the head 13, that is, in the embodiment of the present invention, the main shafts 14, 14' and 14" are evenly distributed around the axis AA. The main shafts 14, 14' and 14" are arranged relative to each other so that the projections of their axes BB, BB' and BB" in a plane P orthogonal to the axis AA form a regular n-gon centered on the axis AA, where n is the number of main shafts. Figure 2 In the example shown, the longitudinal axes of the main shafts 14 , 14 ′ and 14 ″ form an equilateral triangle.

[0051] In addition, in a preferred embodiment of the present utility model, the spindles 14, 14' and 14” are arranged such that the spacing distances between their axes B-B, B-B' and B-B” and the axis A-A are greater than the radius of the spindles 14, 14' or 14”, for example, at least corresponding to the diameter of the spindles 14, 14' or 14”. This arrangement allows maximizing the clearance between the cutting tools 15' or 15” in the standby position and the spindles 14' and 14”, thus avoiding the risk of collision between these cutting tools 15' and 15” and the fixture 21 or the workpiece. It should be noted that generally, the more spindles the head includes, the greater the spacing distance between the axis A-A and the axes B-B, B-B' and B-B” of the spindles.

[0052] In addition, particularly as Figure 3 shown, the tool holder 10 is configured such that, due to the structure of the base 12, the axis A-A forms an angle between 35 and 55 degrees, preferably 45 degrees, with respect to the vertical axis. Therefore, the spindles 14, 14' and 14” are arranged on the head 13 such that their axes B-B, B-B' and B-B” are inclined with respect to the axis A-A at an angle between 35 and 55 degrees, preferably 45 degrees, so that in their working positions, they are parallel to the vertical axis, as described above.

[0053] Generally speaking, it can be inferred from the foregoing content and the drawings that the spindles 14, 14' and 14” are symmetrically arranged with respect to the axis A-A, and the axes B-B, B-B' and B-B” of the spindles 14, 14' and 14” do not intersect with each other.

[0054] In addition, the specific arrangement of the spindles 14, 14' and 14” with respect to the head 13 of the tool holder 10 can reduce the force cycle. In fact, the spindles 14, 14' and 14” are fastened as close as possible to the connecting elements, which are formed, for example, by ball bearings, such that the head 13 can pivot with respect to the body 11 of the tool holder 10.

[0055] In addition, the machine tool 20 may include two tool holders 10, which are arranged on both sides of the fixture 21, as Figure 4 shown. As shown in this figure, since there are two tool holders 10, two machining operations can be performed on the same workpiece simultaneously. Advantageously, in the working position, the rotational axes of the spindles 14 of each tool holder 10 may coincide.

[0056] The fixture 21 may take the form of a workbench, which is designed to hold the workpiece in place and has different degrees of translational and rotational mobility.

[0057] As Figure 4As shown, the machine tool 20 may have a protective wall 23 to prevent chips and cutting fluid from splashing. Specifically, the protective wall 23 is arranged in a liquid-tight manner around the body 11 of the tool holder 10 or each tool holder 10, and for this purpose includes an opening through which the body 11 engages. The opening may include an oil scraping seal arranged against the body 11 at its periphery. In addition, the protective wall 23 may advantageously include corrugations. The oil scraping seal and the corrugations allow the liquid-tightness to be maintained during the movement of the tool holder in three directions of X, Y, and Z.

[0058] The protective wall 23 is fastened to the frame 22 of the machine tool 20 through its periphery.

[0059] In addition, each protective wall 23 advantageously extends in a plane orthogonal to the axis A-A, that is, in a plane inclined with respect to the horizontal axis, which allows the flow of the cutting fluid and the chips to be promoted. This arrangement also makes it easier for the operator to access the fixture 21 and the spindles 14, 14' or 14".

[0060] More generally, it should be noted that the embodiments and manufacturing methods considered above have been described as non-limiting examples, and thus other variants can be envisaged.

Claims

1. A tool holder (10) comprising a body (11) extending along an axis AA, said body (11) comprising a base (12) at one end and a rotatably movable head (13) at the other end, said base (12) being intended to be fastened to a numerically controlled machine tool (20), said head (13) comprising at least two spindles (14, 14', 14") for holding the tools, each spindle being intended to receive a cutting tool (15, 15', 15") in engagement, characterized in that These spindles (14, 14', 14") occupy, depending on the angular position of the head (13), either a working position in which they are used to perform machining operations on a workpiece held in position in a fixture (21) or a standby position in which they are withdrawn from the workpiece, each spindle (14, 14', 14") being configured to be controlled independently of the other spindles so that a cutting tool (15, 15', 15") carried by it is either stationary or driven in rotation, regardless of the position occupied by the spindle.

2. The tool holder (10) according to claim 1, characterized in that The axis of rotation of the head (13) coincides with the axis AA.

3. The tool holder (10) according to claim 2, characterized in that The base (12) is configured such that the axis AA forms an angle between 35 degrees and 55 degrees relative to a vertical axis.

4. The tool holder (10) according to any one of claims 1 to 3, characterized in that The main shafts (14, 14', 14") are distributed around the axis of rotation of the head (13), and each main shaft (14, 14', 14") is arranged so that the axes (BB, BB', BB") of the main shafts form an angle between 35 degrees and 55 degrees with respect to the axis AA, and the axes (BB, BB', BB") of the main shafts do not intersect each other.

5. The tool holder (10) according to claim 4, characterized in that The main axes (14, 14', 14") are arranged relative to each other so that the projections of their axes (BB, BB', BB") in a plane P orthogonal to the axis AA form a regular n-gon centered on the axis AA, where n is the number of the main axes (14, 14', 14").

6. The tool holder (10) according to any one of claims 1 to 3, characterized in that The main shafts (14, 14', 14") are arranged such that their axes (BB, BB', BB") are spaced from the axis AA at a distance greater than the radius of the main shafts (14, 14', 14").

7. The tool holder (10) according to any one of claims 1 to 3, characterized in that Each spindle (14, 14', 14") includes its own motor for rotating or stationary the cutting tool (15, 15', 15") carried by each spindle.

8. The tool holder (10) according to any one of claims 1 to 3, characterized in that At least one spindle (14, 14', 14") is adapted to occupy at least two different working positions, each of which is defined by a predetermined angular position of the head (13) of the tool holder (10).

9. The tool holder (10) according to any one of claims 1 to 3, characterized in that At least one spindle (14, 14', 14") is adapted to continuously occupy a working position during the rotation of the head (13) of the tool holder (10).

10. A numerically controlled machine tool (20), characterized in that: The CNC machine tool (20) includes at least one tool holder (10) according to any one of claims 1 to 9, and the tool holder (10) is directly fastened to the frame (22) or a carrier capable of translational movement in three directions XYZ through the base (12), so that the axis AA forms an angle between 35 degrees and 55 degrees relative to the vertical axis, and the CNC machine tool also includes a clamp (21) for holding the workpiece to be processed in place.

11. The numerically controlled machine tool (20) according to claim 10, characterized in that: The numerically controlled machine tool (20) comprises two tool holders (10) arranged on both sides of the fixture (21).

12. The numerically controlled machine tool (20) according to claim 10 or 11, characterized in that: The numerically controlled machine tool (20) comprises a protective wall (23) for preventing chips and cutting fluid from splashing, and the body (11) of the tool holder (10) is engaged in a corresponding opening of the protective wall (23) in a liquid-tight manner.

Images