Claws and chucks

Abstract

The invention relates to a chuck jaw for a chuck (1), having a jaw body (6), at which at least one jaw step (7) is formed, which has a step head (9) for holding a clamping insert (10), which has a sensor (16) at its end face (22), the clamping insert being formed from one base leg (11) and two fastening legs (12) which extend from the base leg (11). On the opposite longitudinal sides of the step head (9) there are respectively formed threaded holes (32) for receiving fastening screws (33), the screw heads (34) of which are received in through openings (35) which are formed in the fastening legs (12) of the clamping insert (10) which are assigned to the longitudinal sides, wherein the longitudinal axis of the threaded hole (32) on each side has an offset from the through opening (35) which is assigned to the longitudinal axis when the base leg (11) lies against the end face (22). The invention also relates to a chuck (1).

Description

Technical Field

[0001] This invention relates to a chuck jaw having a jaw body with at least one jaw step formed therein. The jaw step has a stepped head for holding a clamping insert, the stepped head having a sensor at its end face. The clamping insert is formed by a base leg and two fastening legs extending from the base leg. Threaded holes for receiving fastening screws are formed on opposite longitudinal sides of the stepped head, the screw heads of the fastening screws being received in through openings formed in the fastening legs of the clamping insert assigned to the longitudinal sides. Furthermore, when the base leg abuts against the end face, on each side, the longitudinal axis of the threaded hole is offset from the through opening assigned to the longitudinal axis. The invention also relates to a chuck. Background Technology

[0002] Clamping devices such as chucks are subjected to various disturbances during operation, particularly centrifugal force, effective friction, and wear. Therefore, even if the operating force is known, the clamping force acting on the tool or workpiece to be clamped can never be accurately determined. This is disadvantageous in the operation of the clamping device, as insufficient clamping force may cause the clamped object to be thrown out. Furthermore, it may impair machining accuracy, as excessive clamping force may cause deformation, while insufficient clamping force may not guarantee a secure position under uncertain conditions.

[0003] As known from DE 102019 109856A1 by the same inventor, a sensor is arranged at the bending beam in the jaw to detect the jaw, wherein a receiving part for an electronic device housing and an energy storage device is formed in the jaw body, and energy wires and data wires are introduced into the jaw to connect these components. A lateral groove is formed at the stepped head, into which a clamping insert with a guide bar is introduced. Such a jaw has proven useful in that the clamping force can be accurately detected by means of a sensor. However, due to the guide bar, the manufacture of the clamping insert is complex and involves many working steps, and is correspondingly costly.

[0004] A jaw assembly is known from DE 202013 104 141U1, wherein a replacement jaw is replaceably arranged on a carrier jaw, wherein the replacement jaw, designed in a U-shape, is arranged in an opposite groove of the carrier jaw, and a threaded hole is provided in the carrier jaw for receiving a safety screw, the safety screw securing the replacement jaw relative to the carrier jaw with its head. The threaded hole is formed in a stepped portion of the carrier jaw, wherein the area pointing to the replacement jaw is correspondingly determined by the threaded hole. Summary of the Invention

[0005] The basic objective of this invention is to form a chuck of the type described at the outset, thereby simplifying its construction while maintaining the possibility of accurately determining the actually effective clamping force. A further objective of this invention is to provide an improved chuck.

[0006] This objective is achieved by a chuck having the features of claim 1 and a chuck having the features of claim 11. Advantageous designs of the invention with convenient improvements are given in the dependent claims.

[0007] The unique feature of the chuck of the present invention, mentioned at the outset, is that the base legs are formed flat on the side facing the stepped head and can be manufactured very simply, requiring only the additional introduction of the through opening compared to known chucks. This ensures that the clamping force can be detected with constant accuracy by a given offset between the threaded hole and the through opening, which, under a strong load, causes deformation of the clamping insert to such an extent that the force is not absorbed by the screw head, allowing the force to flow through the end face using a sensor. By eliminating the groove for connection with the clamping insert, the rigidity of the chuck is improved, thereby reducing notch stress and thus increasing the service life of the chuck.

[0008] Advantageously, the fastening screw is formed as a columnar screw with a columnar screw head. Additionally, the corresponding cutout in the clamping insert can be implemented slightly larger and slightly offset in position, so that the screw head is not supported at the cutout of the clamping insert when clamping the workpiece and thus does not interfere with the force flow. When an undercut with a bracket radius is formed at the bottom of the claw step portion below the stepped head, and when grooves extending parallel to the end face are formed on both sides of the stepped head, offset relative to the threaded hole towards the end face, it facilitates the defined force input into the stepped head. It should be noted that these grooves are not used for coupling the clamping insert and are therefore functionally different from the grooves used for coupling the clamping insert, and in particular, can have a reduced depth.

[0009] When the end face extends obliquely from the outside to the inside relative to the longitudinal axis at a bracket angle at the stepped head, a pull-down effect exists when clamping the workpiece or tool, wherein the pull-down action is helpful and reliably handled when the bracket angle is between 7° and 12°, especially 10°.

[0010] Another advantage is that the base legs of the clamping insert extend obliquely towards the end face at a clamping insert-bracket angle that is 0.20° to 0.50° smaller than the bracket angle. This creates a reserved angle Δα, which provides more uniform surface pressure at the end face and results in less wear.

[0011] When workpieces with customized clamping diameters must be clamped, relatively soft clamping inserts are used, which are unscrewed from their installed state using a rotary tool. If these soft clamping inserts are secured with a cylindrical screw head, their position may be undefined, and the clamping inserts may vibrate during unscrewing. This results in poor surface quality and poor dimensional accuracy. Therefore, a clamping insert that needs to be unscrewed is provided along with a countersunk screw, wherein the through-hole has a tapered surface on the outside as a countersunk hole. This precisely pre-determines the positioning and effectively suppresses vibration.

[0012] Here, the longitudinal axis defined by the tapered surface has an average offset from the longitudinal axis of the threaded hole to which it is fitted. This causes the insert to be pulled relative to the stepped head when the countersunk screw is tightened, eliminating any possible gaps and ultimately creating a defined position. After unscrewing, the countersunk screw can be replaced again with a fastening screw having a columnar screw head.

[0013] To minimize notch stress in the chuck's claw guides, a T-shaped guide bar is formed in the claw body, with an undercut portion having a double backcut in each throat. This results in a significant increase in radius, while the area of ​​the claw guides remains almost unchanged.

[0014] The aforementioned effects and advantages also apply meaningfully to chucks with the aforementioned type of jaws.

[0015] Without departing from the framework of the invention, the features and combinations of features mentioned above in the specification, as well as those mentioned below in the description of the drawings and / or shown separately in the drawings, can be used not only in the corresponding given combinations, but also in other combinations or individually. Therefore, embodiments not explicitly shown or explained in the drawings can also be considered as being included and disclosed by the invention, but which are apparent and can be produced from the described embodiments by individual combinations of features. Attached Figure Description

[0016] Further advantages, features, and details of the invention will become apparent from the claims, the hereinafter description of preferred embodiments, and with the aid of the accompanying drawings. In the drawings:

[0017] Figure 1A perspective view shows a chuck with three jaws and a workpiece clamped under external gripping, with symbols indicating data transmission from one of these jaws.

[0018] Figure 2 A perspective view of the detached jaws without clamping inserts is shown.

[0019] Figure 3 Showing with Figure 2 The corresponding diagram shows separate jaws with two clamping inserts.

[0020] Figure 4 Show Figure 3 A top view of the chuck's claw.

[0021] Figure 5 Show Figure 3 Side view of the chuck claw.

[0022] Figure 6 A perspective view of the separated clamping insert is shown.

[0023] Figure 7 With Figure 6 Different perspectives show the three-dimensional views of the separated clamping inserts.

[0024] Figure 8 Show Figure 3 A front view of the chuck claw.

[0025] Figure 9 Show along Figure 8 The cross section of line IX-IX,

[0026] Figure 10 Show Figure 8 The cross section XX,

[0027] Figure 11 Showing with Figure 9 The corresponding diagram shows the orientation of the clamping insert.

[0028] Figure 12 Show Figure 11 Details XII,

[0029] Figure 13 Showing with Figure 3 The corresponding illustration shows an alternative clamping insert at the upper jaw head.

[0030] Figure 14 Show Figure 13 Side view of the chuck claw.

[0031] Figure 15 Show Figure 14 The cross section XV-XV,

[0032] Figure 16 Show Figure 15 Details of XVI

[0033] Figure 17 Show Figure 1 Side view of the chuck.

[0034] Figure 18 Show Figure 8 Details of XVIII, and

[0035] Figure 19 Show Figure 17 Details XIX. Detailed Implementation

[0036] exist Figure 1 The diagram illustrates a chuck 1 having a disc body 2 in which jaws 4 are arranged, with radial jaw guides 3 evenly distributed around its periphery. The illustrated embodiment shows three radial jaw guides 3 and correspondingly inserted jaws 4; however, different numbers of radial jaw guides 3 and corresponding jaws 4 are also possible, particularly chucks 1 with two jaws 4 or 4, 5, 6, or more than 6 jaws 4. In controlled insertion, the chuck 1 is typically assigned to the machine tool's work spindle, where the machine tool rotates and drives the chuck 1, providing actuation force to generate the desired clamping force. Figure 1 The radio waves, represented by the symbol, indicate the wireless transmission of data to be transmitted from the jaw 4 used in the chuck 1 to the receiving unit of the machine tool.

[0037] exist Figures 2 to 5 The image shows the jaw 4 itself in detail, and the jaw has a jaw body 6, on which at least one jaw step portion 7 is formed, the jaw step portion having a stepped head 9 for holding the clamping insert 10. Two of these jaw steps 7 are shown in the illustrated embodiment, but it is also applicable here that different numbers can be achieved, i.e., jaw 4 with only one jaw step portion 7, three jaw steps 7, or four or five jaw steps 7, depending on the required clamping ratio. It should be noted that the jaw body 6 of the jaw 4 is designed as a stepped-reversible jaw, meaning that the jaw 4 can be easily rotated into the jaw guide 3 of the chuck 1 to hold the insert 10. Figure 1 The external clamping of the workpiece 31 shown is changed to internal clamping.

[0038] At each claw step 7, the claw 4 has a sensor 16 at the end face 22 of the step head 9. Additionally, the step head 9 is configured to hold a clamping insert 10, which consists of a base leg 11 and two fastening legs 12 extending from the base leg 11. Threaded holes 32 for receiving fastening screws 33 are formed on opposite longitudinal sides of the step head 9, the screw heads 34 of which are received in through openings 35 formed in the fastening legs 12 of the clamping insert 10 that are assigned to the longitudinal side. When the base leg 11 is against the end face 22, on each side, the longitudinal axis of the threaded hole 32 is offset from the through opening 35 assigned to the longitudinal axis. Specifically, as... Figure 10 As shown, the fastening screw 33 is formed as a columnar screw with a columnar screw head. This structure ensures that the insert 10 can deform under effective clamping force such that the clamping force is not absorbed by the screw head 34 and the sensor 16 can accurately detect the effective total clamping force.

[0039] Below the stepped head 9, an undercut portion 20 with a bracket radius is formed at the bottom of the claw stepped portion 7, wherein grooves 21 are respectively formed on both sides of the stepped head 9 in the direction toward the end face 22, offset relative to the threaded hole 32, the grooves extending parallel to the end face 22, thereby defining a defined area for introducing force.

[0040] End face 22 extends obliquely from the outside to the inside relative to the longitudinal axis at a bracket angle at the step head 9, wherein Figure 11 and 12 In the embodiment shown, the bracket angle is 10°. It should be noted that the side of the pointing end face 22 of the base leg 11 of the clamping insert extends obliquely at a clamping insert-bracket angle, which is 0.20° to 0.50° smaller than the bracket angle. This embodiment shows a clamping insert-bracket angle of 9.75°, thus reserving an angle Δα 0.25° smaller than the bracket angle.

[0041] Figures 13 to 16 The following situation is shown: the workpiece 31 must be clamped with a customized clamping diameter using the clamping insert 36, which needs to be screwed out. The profile achieved by screwing out is... Figure 13 The image is shown in dashed lines. This clamping insert 36, which needs to be unscrewed, is relatively soft, and in any case, more flexible than... Figure 13 The conventional clamping insert 10 shown in the image is softer, featuring corrugated teeth 37. For unscrewing purposes, a clamping insert 36 is provided along with a countersunk screw 38, wherein the through opening 35 has an external tapered surface 39 as a countersunk hole, wherein the longitudinal axis defined by the tapered surface 39 has an average offset Δx from the longitudinal axis of the mating threaded hole 32. Figure 16 Countersunk screws 38 are used for unscrewing purposes to ensure unique identification of the position of the clamping insert 36 that needs to be unscrewed, wherein after unscrewing, the countersunk screws 38 are replaced with fastening screws 33 having columnar screw heads 34. Figure 15 It is shown in the middle on the bottom side.

[0042] Figure 18 and Figure 19 This involves forming a T-shaped guide bar 30 at the claw body 6, wherein an undercut portion 40 with a double backcut portion 41 is formed in each throat, relative to... Figure 19 The conventional design shown in the dashed line allows for an increase in radius to reduce notch stress.

[0043] Generally, it is applicable to form a sensor point 15 for arranging the sensor 16 at the end face 22. Here, the sensor point 15 is formed by a pocket-shaped portion 17, in which the sensor 16 is arranged. The sensor 16 itself is formed as a strain gauge 18, particularly a metal strain gauge, welded to the pocket-shaped portion 17, wherein the contact surface is arranged on a channel 19, providing the channel for passing through data wires and / or power supply wires 24. Figure 9 ).

[0044] The clamping insert 10 itself has a U-shaped cross-section design, wherein a matching pouch-shaped portion 23 is formed on the inner side of the base support leg 11 in the middle between the fastening support legs 12, and its size matches the size of the pouch-shaped portion 17.

[0045] If the workpiece is clamped now, such as from... Figure 1 As can be seen, by the hollowed-out portion formed by the paired bag-shaped portion 23 in the clamping insert 10 and the bag-shaped portion 17 in the end face, the paired bag-shaped portion is bent, i.e. stretched, in a defined manner according to the type of bending beam. This also acts on the strain gauge 18, which causes a change in resistance or voltage proportional to the effective clamping force. The undercut portion 20 below the stepped head 9 here facilitates an undisturbed and uniform force flow.

[0046] It should also be noted that, to protect the sensor 16, the pouch-like portion 17 receiving the sensor 10 is enclosed by a cover, which is preferably only removable through a destructive means. Finally, a first receiving portion 26 for the electronic device housing 27 is provided in the claw body 6, connected to the pouch-like portion 17 via a channel 19. A second receiving portion 28 for the energy storage device 29, particularly a power storage unit such as a battery or capacitor, is also provided in the claw body 6, similarly connected to the channel 19 of the pouch-like portion 17. Thus, data detected by the metal strain gauge 18 can be fed into the electronic device housing 27, which houses the electronic components required for data detection and analysis, where raw or processed data from the sensor 16 is provided non-contactly via the machine tool's receiving unit.

[0047] List of reference numerals

[0048] 1. Chuck

[0049] 2. Disk body

[0050] 3-claw guide

[0051] 4. Claws

[0052] 5. Radio waves

[0053] 6 claw body

[0054] 7. Claw-shaped stepped section

[0055] 9-step head

[0056] 10 Clamping inserts

[0057] 11 Base support legs

[0058] 12 Secure the outriggers

[0059] 15 sensor points

[0060] 16 sensors

[0061] 17. Bag-like portion

[0062] 18 Strain gauges

[0063] 19 channels

[0064] 20 Undercut

[0065] 21 Grooves

[0066] 22 End face

[0067] 23 Paired pouches

[0068] 24 Data cables / Power cables

[0069] 26 First Reception Department

[0070] 27 Electronic device housing

[0071] 28 Second Reception Department

[0072] 29 Energy Storage

[0073] 30 guide strips

[0074] 31 Workpiece

[0075] 32 threaded hole

[0076] 33 Fastening screws

[0077] 34 Screw head

[0078] 35. Through opening

[0079] 36. Clamping inserts that need to be unscrewed

[0080] 37 Corrugated teeth

[0081] 38 Countersunk Screws

[0082] 39 Conical surface

[0083] Δα Reserved angle

[0084] Δx Average offset

Claims

1. A jaw (4) for a chuck (1), the jaw having a jaw body (6) with at least one jaw step (7) formed thereon, the jaw step having a stepped head (9) for holding a clamping insert (10), the stepped head having a sensor at its end face (22), the clamping insert being formed by a base leg (11) and two fastening legs (12) extending from the base leg (11), characterized in that, Threaded holes (32) for receiving fastening screws (33) are formed on opposite longitudinal sides of the stepped head (9), the screw heads (34) of which are accommodated in through openings (35) formed in fastening legs (12) of the clamping insert (10) assigned to the longitudinal sides, and when the base legs (11) abut the end face (22), the longitudinal axis of the threaded holes (32) is offset from the through openings (35) assigned to the longitudinal axis on each opposite longitudinal side.

2. The gripper (4) according to claim 1, characterized in that, The fastening screw (33) is formed as a columnar screw with a columnar screw head (34).

3. The gripper (4) according to claim 1 or 2, characterized in that, Below the step head (9), an undercut portion (20) with a bracket radius is formed at the bottom of the claw step portion.

4. The chuck (4) according to claim 3, characterized in that, On both sides of the stepped head (9), grooves (21) are respectively formed offset relative to the threaded hole (32) in the direction toward the end face (22), and the grooves extend parallel to the end face (22).

5. The chuck (4) according to claim 1 or 2, characterized in that, The end face (22) extends obliquely from the outside to the inside relative to the longitudinal axis at a bracket angle at the step head (9).

6. The chuck (4) according to claim 5, characterized in that, The bracket angle is between 7° and 12°.

7. The chuck (4) according to claim 5, characterized in that, The base leg (11) of the clamping insert (10) extends obliquely toward the end face (22) at a clamping insert-bracket angle that is 0.20° to 0.50° smaller than the bracket angle.

8. The chuck (4) according to claim 1 or 2, characterized in that, Together with the countersunk screw (38), a clamping insert (36) that needs to be unscrewed is provided, wherein the through opening (35) has a tapered surface (39) on the outside as a countersunk hole.

9. The chuck (4) according to claim 8, characterized in that, The longitudinal axis defined by the tapered surface (39) has an average offset Δx from the longitudinal axis of the threaded hole (32) to which it is assigned.

10. The chuck (4) according to claim 1 or 2, characterized in that, A guide bar (30) with a T-shaped cross-section is formed at the claw body (6), wherein a bottom cut (20) with a double back cut is formed in each throat.

11. A chuck (1) having a disc body (2) in which radial claw guides (3) of claws (4) according to any one of claims 1 to 10 are arranged evenly around the periphery.

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