Screw clamp

Abstract

The invention relates to a screw clamp, comprising two clamping arms (1, 3), between which a workpiece (5) can be clamped. In a clamping process, at least one of the clamping arms (1, 3) can be moved by an axial movement distance (∆a1, ∆a2) by means of a clamping unit (6) such that a clamping force acting against the workpiece (5) is built up, which clamping unit can be manually rotationally actuated about an axis of rotation (D). According to the invention, the clamping unit (6) is in the form of a threaded drive comprising a radially outer adjustment sleeve (17) which has at least one internal screw thread (19, 21) and comprising at least one radially inner threaded stroke element (23, 25), the external screw thread of which is in thread engagement with the adjustment sleeve internal screw thread (19, 21) and which can be brought into force-transmitting connection with the movable clamping arm (1, 3). In the clamping process, the adjustment sleeve (17) is rotationally actuated, whereby the threaded stroke element (23, 25), together with the clamping arm (1, 3) connected thereto, is moved against the workpiece (5) by the axial movement distance (∆a1, ∆a2).

Description

[0001] The invention relates to a screw clamp according to the preamble of claim 1.

[0002] From DE 82 14 309 U1, a screw clamp with a movable clamping arm and a stationary clamping arm is known, between which a workpiece can be clamped. The stationary clamping arm has a threaded flange with an internal thread, which engages with a threaded spindle with a pressure plate facing the adjustable clamping arm. The adjustable clamping arm has a slide rail which, in the unclamped state, can be easily guided in a loose fit through a recess in the stationary clamping arm. As a slip-prevention measure, the slide rail of the adjustable clamping arm has knurling which, when the slide rail is tilted, engages with a counter contour of the recess formed in the stationary clamping arm.

[0003] In the prior art, for a clamping operation, the pressure plate of the stationary clamping arm and the movable clamping arm are first brought into contact with the intermediate workpiece. Subsequently, the threaded spindle is rotated, thereby building up a clamping force acting against the workpiece.

[0004] In the above DE 82 14 309 U1, the threaded spindle together with the pressure plate is positioned laterally offset from the slide rail of the adjustable clamping arm by a lever arm length. Depending on the workpiece geometry, such a screw clamp assembly can be subject to interfering contours.

[0005] A screw clamp of this type with two clamping arms is known from US Patent 1,587,820 A.

[0006] A screw clamp according to the preamble of claim 1 is known from US 3,414,909.

[0007] The object of the invention is to provide a screw clamp which is functionally enhanced compared to the prior art and in particular provides an alternative screw clamp design for special workpiece geometries.

[0008] The object of the invention is achieved by the features of claim 1. Preferred embodiments of the invention are disclosed in the dependent claims.

[0009] The invention relates to a screw clamp in which at least one of the two clamping arms is adjustable by an axial travel by means of a clamping unit that can be manually rotated about a rotary axis. During a clamping operation, a clamping force is applied to the workpiece. According to the invention, the clamping unit is implemented as a threaded drive. This drive has a radially outer adjusting sleeve with at least one internal thread and at least one radially inner threaded lifting element. The threaded lifting element engages with the internal thread of the adjusting sleeve via its external thread. Furthermore, the radially inner threaded lifting element can be connected to the adjustable clamping arm (in particular via a locking mechanism) to transmit force. During a clamping operation, the adjusting sleeve is rotated. This rotation of the adjusting sleeve causes the threaded lifting element, along with the clamping arm connected to it, to move by the axial travel against the workpiece, thereby building up tension.

[0010] According to the invention, the adjustable clamping arm has a slide rail which, in the unloaded state, can be easily adjusted in a loose fit by means of a recess in the radially inner threaded lifting element. The slide rail of the adjustable clamping arm has a knurled surface to prevent slippage. If the slide rail is tilted, it can jam against a counter-contour of the recess formed in the threaded lifting element. The recess extends axially through the entire length of the threaded lifting element.

[0011] In the above embodiment, only one clamping arm can be adjusted using the adjusting sleeve. In contrast, a subsequent second embodiment prefers that both clamping arms be adjustable by one axial travel when the adjusting sleeve is rotated. To implement such an adjustment mechanism, the adjusting sleeve can have a first internal thread (e.g., right-hand thread) and an axially adjacent, oppositely oriented second internal thread (e.g., left-hand thread). These threads are each engaged with a first threaded lifting element and a second threaded lifting element. The first threaded lifting element and the second threaded lifting element can each be force-transmittingly connected to one of the adjustable clamping arms. The clamping arms can each be positioned on axially opposite end faces of the adjusting sleeve.

[0012] During a clamping operation, the two threaded lifting elements can be moved towards each other by one stroke by rotating the adjusting sleeve. Conversely, by rotating the adjusting sleeve in the opposite direction, the two threaded lifting elements can be moved away from each other by one stroke.

[0013] In one technical implementation, the slide rail of the first adjustable clamping arm, guided through the recess of the first threaded lifting element, can extend beyond the first threaded lifting element with a slide rail overhang. In this case, the slide rail overhang can represent an interference contour for the adjacent second threaded lifting element. Therefore, the second threaded lifting element can have a clearance into which the slide rail overhang can project without interfering.

[0014] Conversely, the guide rail of the second adjustable clamping arm, guided through the recess of the second threaded lifting element, can also extend beyond the second threaded lifting element with a guide rail overhang. In this case, the guide rail overhang can form an interference contour for the first threaded lifting element. Therefore, the first threaded lifting element can also have a clearance into which the guide rail overhang can project without interfering.

[0015] The clearance in the first threaded lifting element and / or the second threaded lifting element can be dimensioned such that it does not create an interfering contour when the slide rail tilts into its inclined position, in which the slide rail serrations engage with the counter contour of the recess in the respective threaded lifting element to provide anti-slip protection. In one technical implementation, the recess of one threaded lifting element can be aligned axially with the clearance of the other threaded lifting element. Preferably, the clearance cross-section in each threaded lifting element is significantly larger than the recess cross-section.

[0016] To enhance the functionality of the clamp, it is preferred that at least one of the clamping arms has a threaded flange with an internal thread. This flange can engage with a threaded spindle and pressure plate. The pressure plate can face the other clamping arm. During the clamping process, the pressure plate of the threaded spindle can be adjusted by rotating it to increase the clamping force.

[0017] An embodiment of the invention is described below with reference to the accompanying figures.

[0018] They show: Figs. 1 and 2 show the screw clamp in different positions during construction; Fig. 3 shows the screw clamp in a schematic side section view; Fig. 4 shows a detail view of the screw clamp; and Fig. 5 shows a view corresponding to the Fig. 3 the screw clamp in its tensioned state.

[0019] In the Fig. 1 and2 The screw clamp is shown in an untensioned position. Accordingly, the screw clamp has two adjustable clamping arms 1, 3 with an intermediate clamping unit 6. Each of the two clamping arms 1, 3 has in the Fig. 1 or 2 a threaded flange 7 with an internal thread, which is in thread engagement with a threaded spindle 9 with pressure plate 11, each facing the opposite clamping arm.

[0020] Between the two clamping arms 1, 3 is a workpiece 5 ( Fig. 5 ) clampable. For a clamping operation, the two clamping arms 1, 3 can be rotated about an axis of rotation D by means of the Fig. 2 ) manually rotatable clamping unit 6 by an axial travel Δa 1 , Δa 2 ( Fig. 5 The pressure plates 11 of the two clamping arms 1, 3 are adjusted, pressing them against the workpiece 5 and generating a clamping force acting against the workpiece 5. A tool projection 13 for rotary actuation of the threaded spindle 9 is provided at the end of the threaded spindle opposite the pressure plate 11.

[0021] The two clamping arms 1, 3 are in the Fig. 1 and 2 each formed with slide rails 15 which extend in an axial direction through the clamping unit 6.

[0022] The following is based on the Fig. 3 The construction of the clamping unit 6 is described as follows: Accordingly, the clamping unit 6 is implemented as a threaded drive comprising a radially outer adjusting sleeve 17 with a first internal thread 19 (e.g., right-hand thread) and an axially immediately adjacent, oppositely oriented second internal thread 21 (e.g., left-hand thread). Each of the two adjusting sleeve internal threads 19, 21 is engaged with a first threaded lifting element 23 and a second threaded lifting element 25.

[0023] In the Fig. 3 The screw clamp is shown in its untensioned state. Accordingly, the two slide rails 15 (in the Fig. 3 (Only a slide rail 15 is shown) of the left-hand, first clamping arm 1 is guided in a loose fit, freely adjustable through a recess 27 of the left-hand, first threaded lifting element 23. The slide rail 15 extends further with a slide rail projection 29 beyond the first, left-hand threaded lifting element 23. The slide rail projection 29 protrudes in the Fig. 3 free of interference contours, a clearance 31 of the second, right-hand threaded lifting element 25.

[0024] Similarly, the one in the Fig. 3 The sliding rail 15 of the right-hand, second clamping arm 3 (not shown) is guided in a loose fit and is easily adjustable through a recess 27 of the right-hand, second threaded lifting element 25. In this case, the sliding rail 15 extends further (in the Fig. 3 to the left) with a slide rail overhang of 29 (in the Fig. 3 (not shown) to beyond the second, right-hand threaded lifting element 25. The slide rail projection 29 also extends without interference contour through a clearance 31 (in the Fig. 3 (not shown), which is formed in the first, left-hand threaded lifting element 23.

[0025] To provide a slip-resistant surface, the Fig. 3 The sliding rail 15 of the left-hand, first clamping arm 1 has a knurling 33. In the case of an inclination ( Fig. 5 The groove 33 of the slide rail 15 interlocks with a counter contour 35 of the recess 27 formed in the first threaded lifting element 23. In the same way, a slip protection is also provided between the slide rail 15 of the right-hand, second clamping arm 3 and the second threaded lifting element 25.

[0026] As shown in the detailed view of the Fig. 4 As indicated, both the first threaded lifting element 23 and the second threaded lifting element 25 each have a recess 27 and a clearance 31. The recess 27 of one threaded lifting element 23 is aligned axially with the clearance 31 of the other threaded lifting element 25. Furthermore, the clearance 31 in one threaded lifting element 23 is dimensioned to be large enough that it does not interfere with a tilting movement K of the slide rail 15 into its inclined position ( Fig. 5 ) represents. In the tilted position ( Fig. 5 ) tilts the sliding rail knurling 33 with the counter contour 35 of the recess 27 in the respective threaded lifting element 23, 25 to achieve a slip protection.

[0027] For a clamping operation, the workpiece 5 is first positioned between the two pressure plates 11 of the clamping arms 1, 3. Then, the two clamping arms 1, 3, which are not yet tilted, are pressed smoothly until they are in contact with the workpiece 5. This results in a slight tilting movement K ( Fig. 5 ) of the two clamping arms 1, 3, causing the guide rail serrations 33 to interlock with the corresponding counter contours 35 of the two threaded lifting elements 23, 25. This results in a force-fit connection between the respective clamping arm 1, 3 and the associated threaded lifting element 23, 25.

[0028] Subsequently, the adjusting sleeve 17 is rotated, causing the two threaded lifting elements 23, 25 to move from their initial position ( Fig. 3 ) around the path length Δa 1 , Δa 2 (in the Fig. 5 (exaggeratedly large representation) to move towards each other, thereby building up a clamping force acting on the workpiece 5. Bezugszeichen

[0029] 1, 3 Clamping arms 5 Workpiece 6 Clamping unit 7 Threaded flange 9 Threaded spindle 11 Pressure plate 13 Tool attachment 15 Slide rails 17 Adjusting sleeve 19 First internal thread 21 Second internal thread 23 First thread lift element 25 Second thread lift element 27 Recess 29 Slide rail projection 31 Clearance 33 Serration 35 Counter contour D Axis of rotation E Adjusting sleeve center transverse plane Δa 1 , Δa 2 Axial travel K Tilting movement

Claims

1. Screw clamp having two clamping arms (1, 3), between which a workpiece (5) is clampable, wherein, in a clamping process, at least one of the clamping arms (1, 3) is adjustable by an axial adjustment path (Δa1, Δa2) by means of a clamping unit (6) which is manually rotationally actuable about an axis of rotation (D), namely while building up a clamping force acting against the workpiece (5), wherein the clamping unit (6) is realized as a threaded drive which has a radially outer adjusting sleeve (17) with at least one internal thread (19, 21) as well as at least one radially inner threaded stroke element (23, 25), which, with its external thread, is in threaded engagement with the adjusting-sleeve internal thread (19, 21) and is bringable into force-transmitting connection with the adjustable clamping arm (1, 3), and in that, in the clamping process, the adjusting sleeve (17) is rotationally actuated, whereby the threaded stroke element (23, 25), together with the clamping arm (1, 3) connected thereto, is adjusted against the workpiece (5) by the axial adjustment path (Δa1, Δa2), in that, for the force-transmitting connection between the adjustable clamping arm (1, 3) and the threaded stroke element (23, 25), a slide rail (15) connected to the adjustable clamping arm (1, 3) is provided, characterized in that the slide rail (15), in the unclamped state, is guidable in a loose fit in a smoothly adjustable manner through a recess (27) of the radially inner threaded stroke element (23, 25), and in that the slide rail (15), as a slip protection, has a corrugation (33) which, in the case of an inclined position of the slide rail (15), cants with a counter-contour (35) of the recess (27) formed in the threaded stroke element (23, 25), and in that the recess (27) passes axially continuously through the threaded stroke element (23, 25).

2. Screw clamp according to claim 1, characterized in that the two clamping arms (1, 3) are adjustable, upon a rotary actuation of the clamping unit (6), each by an axial adjustment path (Δa1, Δa2), and in that the adjusting sleeve (17) has a first internal thread (19) as well as an axially adjacent, oppositely directed second internal thread (21), which are each in threaded engagement with a first threaded stroke element (23) and with a second threaded stroke element (25).

3. Screw clamp according to claim 2, characterized in that the first threaded stroke element (23) and the second threaded stroke element (25) are each connectable in a force-transmitting manner with one of the clamping arms (1, 3).

4. Screw clamp according to one of the preceding claims, characterized in that the two clamping arms (1, 3) are positioned, in the axial direction, on opposite end faces of the adjusting sleeve, and / or in that, in a clamping process by means of rotary actuation of the adjusting sleeve (17), the two threaded stroke elements (23, 25) are each movable toward one another by the adjustment path (Δa1, Δa2).

5. Screw clamp according to claim 2, 3 or 4, characterized in that the first internal thread (19) and the oppositely directed second internal thread (21) of the adjusting sleeve (17), namely at a center cross plane (E), merge directly into one another in the axial direction.

6. Screw clamp according to claim 2, 3, 4 or 5, characterized in that the slide rail (15) of the first adjustable clamping arm (1), guided through the recess (27) of the first threaded stroke element (23), extends, with a slide-rail projection (29), beyond the first threaded stroke element (23), and in that the second threaded stroke element (25) has a clearance (31) into which the slide-rail projection (29) projects free of interfering contours, and / or in that, conversely, the slide rail (15) of the second adjustable clamping arm (3), guided through the recess (27) of the second threaded stroke element (25), extends, with a slide-rail projection (29), beyond the second threaded stroke element (23), and in that the first threaded stroke element (25) has a clearance (31) into which the slide-rail projection (29) projects free of interfering contours.

7. Screw clamp according to claim 6, characterized in that the clearance (31) in the first threaded stroke element (23) and / or in the second threaded stroke element (25) is dimensioned such that the clearance (31) does not form an interfering contour during a tilting movement (K) of the slide rail (15) into its inclined position, in which the slide-rail corrugation (33) cants with the counter-contour (35) of the recess (27) in the respective threaded stroke element (23, 25) for providing the slip protection.

8. Screw clamp according to claim 6 or 7, characterized in that the recess (27) of the one threaded stroke element (23) is aligned in axial alignment with the clearance (31) of the other threaded stroke element (25).

9. Screw clamp according to one of the preceding claims, characterized in that, on at least one of the clamping arms (1, 3), a threaded flange (7) provided with an internal thread is formed, which is in threaded engagement with a threaded spindle (9) with a pressure plate (11)facing the other clamping arm (1, 3), and in that, in the clamping process, by rotary actuation of the threaded spindle (9), its pressure plate (11) is adjustable for an additional build-up of tension, and in that the threaded spindle (9) with pressure plate (11) is positioned axis-parallel at an axial distance from the axis of rotation (D) of the adjusting sleeve (17).

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