Surface-treated component and manufacturing and assembly method for component

Abstract

To provide a surface-treated component without requiring much time and which is unlikely to cause unevenness in a treatment film, and a method for manufacturing and assembling the component.SOLUTION: A surface-treated component is a component having an inner cylindrical surface and a step surface adjacent to the inner cylindrical surface, and the inner cylindrical surface is engageable with the outer cylindrical surface of a mating component, a threaded hole which is a blind hole is formed in the step surface, at least the inner cylindrical surface is surface-treated, the inside of the threaded hole is not surface-treated, and an adjacent surface on the inner cylindrical surface closest to the threaded hole is located radially outward relative to the inner cylindrical surface other than the adjacent surface.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a surface-treated part and a method for manufacturing and assembling the part. [Background technology]

[0002] For example, a direct drive motor is an electric motor that employs a drive system that transmits torque directly to a rotor and rotates the rotor in a predetermined direction relative to a rotated body without using a transmission mechanism such as a gear, belt, or roller. It is desirable to perform a surface treatment on the rotor and other parts used in a direct drive motor in order to improve, for example, hardness and corrosion resistance.

[0003] One example of surface treatment is electroless plating. Patent Document 1 discloses a technique for improving the hardness of the tooth surface of a gear used in an electric power steering device by applying electroless plating to the tooth surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-122135 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a part to be surface-treated has a screw hole or the like, applying treatment to the inside of the screw hole can cause problems such as changes in the screw dimensions and shape. To prevent this, it is desirable to perform a masking treatment so that the treatment liquid does not reach the inside of the screw hole, but masking each screw hole is time-consuming. In contrast, by screwing a bolt into the screw hole, the treatment liquid does not reach the inside of the screw hole, so the masking effect can be obtained without time-consuming. However, it has been found that problems such as uneven film thickness occur when surface treatment is performed with a bolt screwed into the screw hole.

[0006] The present invention has been made in view of the above problems, and has an object to provide a part that has been subjected to a surface treatment that is less time-consuming and reduces the occurrence of unevenness in the treatment film, and a method for manufacturing and assembling the part. [Means for solving the problem]

[0007] The parts subjected to the surface treatment of the present invention are A component having an inner cylindrical surface and a step surface adjacent to the inner cylindrical surface, The inner cylindrical surface is engageable with an outer cylindrical surface of a mating component, A screw hole which is a blind hole is formed in the step surface, the inner cylindrical surface is surface-treated, and the inside of the screw hole is not surface-treated; The present invention is characterized in that a proximity surface on the inner cylindrical surface closest to the screw hole is located radially outward with respect to the inner cylindrical surface other than the proximity surface. Effect of the Invention

[0008] According to the present invention, it is possible to provide a part that has been subjected to a surface treatment that is less time-consuming and reduces the occurrence of unevenness in the treatment film, and a method for manufacturing and assembling the part. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of a direct drive motor. [Diagram 2] FIG. 2 is a diagram showing a second support member according to the first embodiment, which is illustrated in a simplified manner. [Diagram 3] FIG. 3 is a diagram showing a second support member according to a second embodiment shown in a simplified manner. [Figure 4] FIG. 4 is a cross-sectional view of a second support member to which a masking bolt according to a modified example is attached. [Diagram 5] FIG. 5 is a cross-sectional view showing an example of a second support member in which the screw hole cannot be a through hole. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a direct drive motor 1 having components that have been subjected to a surface treatment according to this embodiment.

[0011] The direct drive motor 1 is used in, for example, inspection equipment, machine tools, semiconductor manufacturing equipment, and the like, to drive an object.

[0012] 1, the direct drive motor 1 includes a motor section 2 for generating power, a rotation detector (not shown) that detects the rotation of the motor section 2, a housing 4 that houses and holds the motor section 2 and the rotation detector, and lead wires 10 that are connected to the motor section 2. Although not shown, the lead wires 10 are drawn out from a connector (not shown) and are connected to a control device that controls the direct drive motor 1.

[0013] The motor unit 2 has a stator 21 and a rotor 22 that is rotatable relative to the stator 21. The rotor 22 rotates about a rotation axis X.

[0014] The direct drive motor 1 of this embodiment is an inner rotor type. The stator 21 is disposed around the rotor 22. That is, the stator 21 is disposed radially outward of the rotor 22 with respect to the rotation axis X.

[0015] 1, the stator 21 has a stator core 25 including a plurality of teeth 23 and a yoke connecting the plurality of teeth 23, and a coil 26 supported by the stator core 25. The teeth 23 are arranged around the rotation axis X, and the coil 26 is supported by each of the plurality of teeth 23.

[0016] The coil 26 includes concentrated winding 14. The coil 26 formed by concentrated winding of the winding 14 is supported by the teeth 23. One coil 26 is disposed on one tooth 23. Here, concentrated winding refers to winding in which a winding is wound multiple times around one tooth 23, in other words, winding of one phase around one tooth 23.

[0017] 1, the winding 14 is wound around a bobbin 28, which is supported by the teeth 23. That is, the coil 26 is composed of the winding 14 concentratedly wound around the bobbin 28 and the bobbin 28 supported by the teeth 23. The coil 26 is covered from both axial sides by a first protective cover member 6 and a second protective cover member 8 attached to the housing 4.

[0018] A plurality of coils 26 formed by concentrically winding the winding 14 around a bobbin 28 are inserted into each of the teeth 23 .

[0019] The rotor 22 has a plurality of permanent magnets 13 arranged at equal intervals around the rotation axis X. The stator 21 and the rotor 22 face each other in the radial direction with a gap therebetween.

[0020] The housing 4 that holds the motor unit 2 and the rotation detector includes a stator housing 4A and a rotor housing 4B. The stator housing 4A has a first housing 41 and a first support member 11. The rotor housing 4B has a second housing 42 and a second support member 12.

[0021] In this embodiment, the first housing 41, the first support member 11, the second housing 42, and the second support member 12 are each a substantially cylindrical member. The first housing 41 and the first support member 11 are connected by a bolt BT1 to form the stator housing 4A. The second housing 42 and the second support member 12 are connected by a bolt BT2 to form the rotor housing 4B. The central axis of the stator housing 4A, the central axis of the rotor housing 4B, and the rotation axis X are coaxial.

[0022] The stator 21 is connected to the first housing 41 constituting the stator housing 4A. As described above, the rotor 22 is configured by assembling a plurality of permanent magnets 13 to the second support member 12 constituting the rotor housing 4B. The second support member 12 will be described in detail later.

[0023] Two bearings 5A, 5B are arranged in series between the stator housing 4A and the rotor housing 4B. The bearings 5A, 5B have an inner ring, an outer ring, and rolling elements arranged between the inner ring and the outer ring. The inner rings of the bearings 5A, 5B are arranged by fitting onto the outer periphery of the first support member 11, and are sandwiched and held between a lower outer periphery step of the first support member 11 and the lower surface of an annular inner ring fixing member 15, and the inner ring fixing member 15 is fastened to the upper surface of the first support member 11 by bolts BT3. That is, the inner rings of the bearings 5A, 5B are attached to the stator housing 4A.

[0024] In contrast, the outer rings of the bearings 5A, 5B are fitted into the inner periphery of the second support member 12 and are sandwiched and held between a lower inner periphery step of the second support member 12 and the lower surface of the annular outer edge portion 42a of the second housing 42. In other words, the outer rings of the bearings 5A, 5B are attached to the rotor housing 4B.

[0025] The rotor housing 4B is supported by the bearings 5A and 5B to be rotatable about the rotation axis X relative to the stator housing 4A.

[0026] When the direct drive motor 1 configured in this manner is supplied with power from the outside via a connector (not shown), the coil 26 is excited, and the magnetic force generated thereby rotates the rotor 22 relative to the stator 21, causing the rotor housing 4B to rotate about the rotation axis X relative to the stator housing 4A.

[0027] When a workpiece (not shown) is connected to the rotor housing 4B, the workpiece rotates together with the rotation of the rotor housing 4B. Therefore, the rotor housing 4B functions as an output shaft that rotates about the rotation axis X when the motor unit 2 is operated.

[0028] By the way, when taking the second support member 12 of the direct drive motor 1 as an example, there are cases where it is unavoidable to make the screw hole 12d (see FIG. 2) into which the bolt BT2 is screwed a blind hole (a hole whose back is closed). An example of such a case will be shown below with reference to FIG. 5. (1) The second support member 12 has a large wall thickness at the portion where the screw hole 12d is provided, and if a through hole is to be formed, the overall length of the second support member 12 becomes long, making cutting difficult (see FIG. 5(a)). (2) The screw hole 12d of the second support member 12 has a relatively small diameter, so that the tool strength is insufficient and it is difficult to drill a deep hole (see FIG. 5(b)). (3) In the second support member 12, a tap or hole HL is also formed on the side opposite the screw hole 12d, and when a through hole is formed, it may interfere with the tap or hole HL on the opposite side (see FIG. 5(c)). (4) In the second support member 12, the clearance between the screw hole 12d and the nearby side wall is small, making it impossible to insert a tool DR such as a drill, making it difficult to form a through hole (see Figure 5 (d)).

[0029] The second support member 12 having the screw holes 12d formed therein as blind holes may be subjected to electroless plating or other surface treatment. However, when electroless plating is performed on the second support member 12 constituting the rotor housing 4B, forming the screw holes 12d as blind holes may result in the deposition of a treatment film that may affect the thread diameter of the screw holes 12d, or the treatment liquid remaining in the screw holes 12d may induce the formation of rust.

[0030] One solution to this problem is to form the screw hole 12d using an oversized tap, taking into account the film thickness after surface treatment. However, if the film thickness is too thick, it may be difficult to maintain a valid screw hole shape after surface treatment. Alternatively, the treatment liquid may not spread evenly inside the screw hole 12d, causing the film thickness inside the screw hole 12d to become unstable, making it difficult to maintain a valid screw hole shape after surface treatment.

[0031] In this embodiment, the above-mentioned problem is solved by a time-saving method in which a masking bolt MB (see FIG. 2) having the same thread shape as the bolt BT2 used for assembly is screwed into the screw hole 12d to perform masking. However, the use of the masking bolt MB may cause another problem, which must be solved. The electroless plating process (also called surface treatment) of the second support member 12 according to the first embodiment will be specifically described below.

[0032] (First embodiment) 2 is a diagram showing the second support member 12 according to the first embodiment shown in a simplified manner, where (a) is a top view, (b) is a vertical cross-sectional view, and (c) is a cross-sectional view taken along line IIC-IIC in Fig. 2(b) and viewed from above. Hereinafter, the axis refers to the axis of the second support member 12, and when assembled into the direct drive motor 1, the axis coincides with the rotation axis X.

[0033] The hollow cylindrical second support member 12 has, from above, a first inner peripheral surface (inner peripheral cylindrical surface) 12a and a second inner peripheral surface 12b having a smaller diameter than the first inner peripheral surface 12a. An upwardly facing step surface 12c (perpendicular to the axis of the second support member 12) is formed between the first inner peripheral surface 12a and the second inner peripheral surface 12b, and a plurality of (here, six) screw holes 12d are formed in the step surface 12c.

[0034] In the vicinity of each screw hole 12d, a recess 12e is formed in the first inner peripheral surface 12a adjacent to the step surface 12c when viewed in the axial direction of the second support member 12. The surface facing the radially inward direction of the recess 12e is located radially outward from the first inner peripheral surface 12a, thereby forming a proximity surface. It is preferable that the proximity surface intersects with the step surface 12c. It is preferable that the surface facing the radially inward direction of the recess 12e is a part of a cylindrical surface coaxial with the screw hole 12d, and can be formed by, for example, milling. When performing surface treatment, a masking bolt MB is screwed into each screw hole 12d. A predetermined interval Δ1 is formed between the head of the masking bolt MB and the recess 12e. The interval Δ1 is preferably larger than the thickness of the plating formed in the recess 12e by electroless plating, and more preferably is larger than twice the thickness of the plating. If Δ1 is less than the thickness of the plating, the plating formed on the recess 12e will come into contact with the masking bolt MB, damaging the surface treatment of the recess 12e and its surroundings when removing the masking bolt MB, or the masking bolt MB may become unable to be removed, which is undesirable. Also, the height (axial length) H1 of the recess 12e is longer than the thickness (axial length) of the hexagonal head of the masking bolt MB.

[0035] Next, a description will be given of the surface treatment of the second support member 12. The second support member, in which the masking bolts MB are screwed into each screw hole 12d, is immersed in a treatment liquid for electroless plating, and an electroless plating film is formed on the surface of the second support member 12.

[0036] At this time, a certain gap is created between the head of the masking bolt MB and the surface facing the radial inside of the recess 12e, so that the treatment liquid enters the gap, and as a result, plating of a sufficient thickness can be formed even in the recess 12e. However, no film is formed in the screw hole 12d where the treatment liquid does not enter, and the thread shape is maintained. After the surface treatment, the masking bolt MB is removed. When the direct drive motor 1 is assembled, the bolt BT2 inserted into the through hole of the outer edge portion 42a is screwed into the screw hole 12d, thereby joining the second support member 12 and the second housing 42. That is, the second support member 12 is a part that has been subjected to surface treatment (similar to the second embodiment).

[0037] 1, the outer peripheral surface (outer cylindrical surface) of the outer peripheral portion 42a of the second housing (the mating part) 42 is fitted to the first inner peripheral surface 12a, so the inner diameter of the first inner peripheral surface 12a after surface treatment needs to be precisely set within a predetermined fitting tolerance with respect to the outer diameter of the outer peripheral portion 42a of the second housing 42. Since the inner diameter of the first inner peripheral surface 12a before surface treatment is precisely formed by cutting, it is important to make the film thickness after surface treatment uniform. The lower surface of the outer peripheral portion 42a of the second housing 42 is held in contact with the step surface 12c.

[0038] If the first inner surface 12a did not have the recess 12e, the treatment liquid would not reach the narrow gap between the head of the masking bolt MB and the first inner surface 12a, resulting in an area where the film thickness is locally thin near the screw hole 12d, which may make it difficult to precisely fit the outer edge portion 42a of the second housing 42 onto the first inner surface 12a.

[0039] In contrast, according to the present embodiment, by forming a recess 12e in the first inner surface 12a, plating of a sufficient thickness is formed within the recess 12e, and the thickness of the first inner surface 12a adjacent to the recess 12e can be made uniform (unevenness can be suppressed), thereby making it possible to precisely fit the outer edge portion 42a of the second housing 42 into the first inner surface 12a.

[0040] The effect of providing the recess 12e is particularly noticeable when the thickness of the film after the surface treatment is thick. When the thickness of the film after the surface treatment is thick, the surface treatment has a large effect on the dimensions of the screw hole 12d, and masking is often required. In addition, when the thickness of the film after the surface treatment is thick, the degree of unevenness that occurs also increases, and the effect on the dimensions also increases. The thickness of the film after the surface treatment is preferably 0.04 mm or more.

[0041] For example, by setting the radial protrusion amount of the recess 12e relative to the first inner surface 12a to more than twice the film thickness in the standard surface treatment, even if a film more than twice the film thickness in the standard surface treatment is formed, the recess 12e can be properly fitted to the first inner surface 12a.

[0042] Second embodiment 3A and 3B are diagrams showing a second support member 12A according to a second embodiment shown in a simplified manner, where (a) is a top view, (b) is a vertical cross-sectional view, and (c) is a cross-sectional view taken along line IIIC-IIIC in Fig. 3B as viewed from above. The second support member 12A according to the second embodiment can also be used in the direct drive motor 1 of Fig. 1.

[0043] The hollow cylindrical second support member 12A has, from the top, a first inner peripheral surface 12Aa, a third inner peripheral surface (large diameter cylindrical surface, recessed portion) 12Ae having a larger diameter than the first inner peripheral surface 12Aa, and a second inner peripheral surface 12Ab having a smaller diameter than the first inner peripheral surface 12Aa. In this embodiment, the first inner peripheral surface 12Aa and the third inner peripheral surface 12Ae form an inner peripheral cylindrical surface. An upwardly facing step surface 12Ac is formed between the first inner peripheral surface 12Aa and the third inner peripheral surface 12Ae, and a plurality of (here, six) screw holes 12Ad are formed in the step surface 12Ac. The inner peripheral surface of the third inner peripheral surface 12Ae that intersects with the step surface 12Ac is the adjacent surface.

[0044] The third inner peripheral surface 12Ae, which is coaxial with the first inner peripheral surface 12Aa, can be formed more easily than in the first embodiment by, for example, milling. When performing surface treatment, a masking bolt MB is screwed into each screw hole 12Ad. A predetermined interval Δ2 is formed between the head of the masking bolt MB and the third inner peripheral surface 12Ae. The interval Δ2 is preferably larger than the thickness of the plating formed in the recess 12Ae by electroless plating, and more preferably is larger than twice the thickness of the plating. If Δ2 is equal to or smaller than the thickness of the plating, the plating formed in the recess 12Ae comes into contact with the masking bolt MB, which may damage the surface treatment of the recess 12Ae and its surroundings when removing the masking bolt MB, or the masking bolt MB may not be removed, which is not preferable. In addition, the height (axial length) H2 of the third inner peripheral surface 12Ae is longer than the thickness (axial length) of the head of the masking bolt MB.

[0045] As in the first embodiment, the outer edge of the second housing 42 fits into the first inner surface 12Aa, so the inner diameter of the first inner surface 12Aa after surface treatment must be precisely within a specified fitting tolerance relative to the outer diameter of the outer edge of the second housing 42.

[0046] If the third inner surface 12Ae were not formed, the treatment liquid would not reach the narrow gap between the head of the masking bolt MB and the first inner surface 12a, which would result in an area where the film thickness is locally thin near the screw hole 12Ad, making it difficult to accurately fit the outer edge of the second housing 42 to the first inner surface 12Aa.

[0047] In contrast, according to the present embodiment, by forming a third inner surface 12Ae between the first inner surface 12Aa and the second inner surface 12Ab, plating of sufficient thickness is formed on the third inner surface 12Ae as well, and the thickness of the first inner surface 12a adjacent to the third inner surface 12Ae can also be made uniform, thereby making it possible to precisely fit the outer edge of the second housing 42 into the first inner surface 12Aa.

[0048] (Modification) FIG. 4 is a cross-sectional view of a second support member 12A to which a masking bolt according to a modified example is attached.

[0049] 4(a), a masking bolt MB1 having a hexagonal socket head is screwed into a screw hole 12Ad. Since the outer periphery of the head of the masking bolt MB1 is cylindrical, the diameter of the third inner circumferential surface 12Ae can be kept small.

[0050] 4(b), a masking bolt MB2 having a hemispherical or partially spherical head is screwed into the screw hole 12Ad. Because the head of the masking bolt MB2 is hemispherical or partially spherical, it is easy to ensure a gap between the upper end of the head and the third inner circumferential surface 12Ae.

[0051] 4(c), a masking bolt MB3, which is a flat head screw, is screwed into the screw hole 12Ad. Since the head of the masking bolt MB3 is relatively thin, the amount of machining of the third inner circumferential surface 12Ae can be reduced accordingly.

[0052] In the modified example shown in Fig. 4(d), a masking bolt MB4 as a threaded pin is screwed into the screw hole 12Ad. Since the head of the masking bolt MB4 has a pin shape, the diameter of the third inner peripheral surface 12Ae can be kept small. In addition, the surface treatment can be performed on the step surface up to the edge of the screw hole 12d.

[0053] The masking bolt according to the above modified example can be used in the first embodiment in the same manner.

[0054] The present invention is not limited to the above-described embodiment, and the configurations of the embodiment may be combined with each other, and modifications and applications by those skilled in the art based on the description in the specification and well-known techniques are also contemplated by the present invention and are included in the scope of protection sought. For example, the part subjected to the surface treatment is not limited to the second support member 12, but may be another part of the direct drive motor 1, or may be another part other than the direct drive motor 1.

[0055] As described above, the present specification discloses the following: (1) A component having an inner cylindrical surface and a step surface adjacent to the inner cylindrical surface, The inner cylindrical surface is engageable with an outer cylindrical surface of a mating component, A screw hole which is a blind hole is formed in the step surface, At least the inner cylindrical surface is surface-treated, and the inside of the screw hole is not surface-treated; a proximate surface of the inner cylindrical surface closest to the screw hole is located radially outward with respect to the inner cylindrical surface other than the proximate surface; A part that has been subjected to a surface treatment. According to this configuration, it is possible to perform surface treatment on the parts that is less likely to cause unevenness in the treatment film.

[0056] (2) A recess is formed on the inner peripheral cylindrical surface, and the adjacent surface is a surface facing radially inward of the recess. A part that has been subjected to the surface treatment described in (1). According to this configuration, the recesses can be easily processed, and the treatment liquid for surface treatment can easily penetrate into the recesses.

[0057] (3) The adjacent surface is a large-diameter cylindrical surface having a diameter larger than that of the inner cylindrical surface. A part that has been subjected to the surface treatment according to (1) or (2). According to this configuration, the treatment liquid efficiently enters the adjacent surface, so that unevenness in the treatment film can be more efficiently suppressed.

[0058] (4) The part constitutes a rotor of a direct drive motor. A part that has been subjected to the surface treatment according to any one of (1) to (3). According to this configuration, even if the housing constituting the direct motor is subjected to a surface treatment, the housing can be assembled with high precision, so that the driving of the direct motor becomes more stable.

[0059] (5) The surface treatment is electroless plating. A part that has been subjected to the surface treatment according to any one of (1) to (4). According to this configuration, the accuracy of the surface treatment on the inner cylindrical surface other than the adjacent surface can be improved.

[0060] (6) A method for manufacturing and assembling a part that has been subjected to a surface treatment according to any one of (1) to (5), comprising the steps of: A masking bolt is screwed into the screw hole of the part and a surface treatment is performed. After the surface treatment, the masking bolt is removed, the outer cylindrical surface of the mating part is fitted to the inner cylindrical surface of the part, and another bolt is screwed into the screw hole to join the part and the mating part. A method for manufacturing and assembling parts. According to this configuration, parts that have been subjected to a surface treatment that is less likely to cause unevenness in the treatment film can be manufactured and assembled without much effort.

[0061] (7) The axial length of the adjacent surface is longer than the axial length of the head of the masking bolt. A method for manufacturing and assembling parts as described in (6). According to this configuration, the accuracy of the surface treatment on the inner cylindrical surface other than the adjacent surface can be improved. [Explanation of symbols]

[0062] 1 Direct Drive Motor 2 Motor section 4A stator housing 4B rotor housing 5A Bearing 5B Bearing 6 First protective cover member 8 Second protective cover member 11 First support member 12, 12A Second support member 13 Permanent magnets 14 Windings 21 Stator 22 Rotor 23 Teeth 41 1st Housing 42 Second Housing MB, MB1, MB2, MB3, MB4 Masking bolt

Claims

1. A component having an inner cylindrical surface and a step surface adjacent to the inner cylindrical surface, The inner cylindrical surface is engageable with an outer cylindrical surface of a mating component, A screw hole which is a blind hole is formed in the step surface, At least the inner cylindrical surface is surface-treated, and the inside of the screw hole is not surface-treated; a proximate surface of the inner cylindrical surface closest to the screw hole is located radially outward with respect to the inner cylindrical surface other than the proximate surface; A part that has been subjected to a surface treatment.

2. A recess is formed on the inner peripheral cylindrical surface, and the adjacent surface is a surface facing radially inward of the recess.

2. A part that has been subjected to the surface treatment according to claim 1.

3. The adjacent surface is a large-diameter cylindrical surface having a diameter larger than that of the inner cylindrical surface.

2. A part that has been subjected to the surface treatment according to claim 1.

4. The component constitutes a rotor of a direct drive motor.

2. A part that has been subjected to the surface treatment according to claim 1.

5. The surface treatment is electroless plating.

2. A part that has been subjected to the surface treatment according to claim 1.

6. A method for manufacturing and assembling a part that has been subjected to the surface treatment according to any one of claims 1 to 5, A masking bolt is screwed into the screw hole of the part and a surface treatment is performed. After the surface treatment, the masking bolt is removed, the outer cylindrical surface of the mating part is fitted to the inner cylindrical surface of the part, and another bolt is screwed into the screw hole to join the part and the mating part. A method for manufacturing and assembling parts.

7. The axial length of the adjacent surface is longer than the axial length of the head of the masking bolt.

7. The method for manufacturing and assembling a part according to claim 6.

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