CN112648965A

CN112648965A - Adjustable deflection instrument

Info

Publication number: CN112648965A
Application number: CN202110008403.0A
Authority: CN
Inventors: 赵国利; 杨丰收; 张建林; 赵伟; 宁海学
Original assignee: Zhejiang Headman Intelligent Equipment Co ltd
Current assignee: Zhejiang Headman Intelligent Equipment Co ltd
Priority date: 2021-01-05
Filing date: 2021-01-05
Publication date: 2021-04-13

Abstract

The invention provides an adjustable deflection instrument, and belongs to the technical field of deflection instruments. It has solved the inconvenient problem of current yaw appearance measurement major possession work piece. The deflection instrument comprises a workbench with a slide rail and two thimble seats, wherein the two thimble seats are arranged on the slide rail and are arranged oppositely, at least one fixture block used for placing a workpiece is arranged between the two thimble seats on the slide rail in a sliding manner, and an adjusting mechanism capable of adjusting the height of the fixture block to enable the workpiece placed on the fixture block to be aligned with the thimble on the thimble seat coaxially is arranged between the fixture block and the slide rail. The deflection instrument can be aligned with the thimble seat only by carrying the workpiece to the clamping block and lifting the clamping block, so that the clamping measurement of the large workpiece is greatly facilitated.

Description

Adjustable deflection instrument

Technical Field

The invention belongs to the technical field of deflection instruments, relates to a deflection instrument, and particularly relates to an adjustable deflection instrument.

Background

The deflection instrument is widely applied to machining shaft parts, and is mainly used for measuring the coaxiality of the shaft parts, particularly the coaxiality of a main shaft of a numerical control lathe. The deflection instrument is mainly composed of two opposite ejector pin bases, the ejector pins on the ejector pin bases can rotate, workpieces are clamped between the two ejector pins and then are clamped tightly through the mutual approaching of the two opposite ejector pin bases, the workpieces and the ejector pins need to be coaxially arranged, a motor capable of rotating the ejector pins can be installed on the common ejector pin bases, the workpieces clamped between the ejector pins can rotate under the driving of the ejector pins, if the motor is not arranged, the workpieces can be rotated through holding the workpieces, and in a word, the workpieces can be rotated. The instrument utilizes two thimbles to position the shaft parts, rotates the part to be measured, and the measuring head directly measures the radial run-out error of the part in the radial direction of the part to be measured.

When the existing deflection instrument measures a workpiece, the workpiece is manually held, then two ends of the workpiece are aligned with the ejector pins, and the workpiece is clamped by moving and fixing the ejector pins on the base. When the workpiece is measured to be large in size or large in mass, people often lift the workpiece by adding hands, the lifting of the large-mass or large-volume workpiece is not a difficult matter, and the difficulty in clamping the large-mass workpiece lies in aligning the large-mass workpiece with the ejector pin on the ejector pin base. Because the staff is more, and the volume is great moreover, leads to the both ends of work piece not to aim at with the thimble well, and the work piece of clamping major possession is wasted time and energy, and such problem is also difficult to solve through increasing the staff. The application of the deflection apparatus is very wide, the same deflection apparatus is often used for measuring workpieces of various sizes or types, so that various workpieces are fixed by the universal deflection apparatus, a specific support cannot be manufactured correspondingly for bearing the workpiece to be measured, the workpiece to be measured needs to rotate when in measurement, the rotation of the workpiece is necessarily influenced by the existence of the support, and the mode is not as convenient and practical as the increase of manpower. In a word, when a workpiece with large mass or volume is fixed between the two ejector pins, time and labor are wasted, and the workpiece is very inconvenient. Therefore, the problem of solving the above existing problem is that the matters to be handled are not buffered at present.

Disclosure of Invention

The invention aims to provide an adjustable yaw instrument aiming at the problems in the prior art. The technical problem that an existing deflection instrument is inconvenient to measure large workpieces is solved.

The purpose of the invention can be realized by the following technical scheme:

the utility model provides an inclined to one side pendulum appearance with adjustable, is including workstation and two thimble seats that have the slide rail the thimble seat all is located the slide rail and sets up relatively, its characterized in that, it is provided with at least one fixture block that is used for placing the work piece to lie in on the slide rail and slide between two thimble seats, be equipped with between fixture block and the slide rail and adjust the fixture block height and make the adjustment mechanism who places the work piece on the fixture block and the thimble coaxial line alignment on the thimble seat.

The thimble seat of this deflection appearance all sets up on the slide rail of workstation, and two thimble seats homoenergetic slide and can stop on the position after the slip along the slide rail. The clamping block is arranged between the two thimble seats, the adjusting mechanism is arranged on the clamping block and can adjust the height of the clamping block, a workpiece is placed on the clamping block by holding the workpiece, then the height of the clamping block is adjusted by the adjusting mechanism to achieve the purpose that the workpiece is aligned with the thimble on the thimble seats coaxially, the workpiece is only required to be carried to the clamping block by designing, the height of the clamping block is adjusted to align the workpiece with the thimbles on the two thimble seats, and the clamping measurement of the large workpiece is greatly facilitated. After the adjusting mechanism is arranged to align the ejector pins, the two ejector pin bases are close to each other and clamp the workpiece, and then the workpiece is separated from the workpiece by moving down the adjusting mechanism, so that the arrangement of the fixture block does not interfere with the rotation measurement of the workpiece, and the workpiece can be very easily measured even if the size or the mass of the workpiece is large.

In the above adjustable yaw meter, the adjusting mechanism includes a limiting seat located on the slide rail, a guide groove is formed in the limiting seat, the fixture block is located inside the guide groove and can slide up and down along the guide groove, a moving block is arranged at the bottom of the guide groove, the bottom surface of the fixture block is an inclined plane, and the moving block abuts against the inclined plane and can move up the fixture block by moving along the inclined direction of the inclined plane.

This adjustment mechanism includes spacing seat, the guide way has been seted up on spacing seat, and the fixture block is located the inboard of guide way, the fixture block receives the spacing of the both sides cell wall of guide way to make the fixture block slide from top to bottom along the guide way from top to bottom, it can not move about in other directions, design like this when the work piece is placed on the fixture block, the fixture block can only upwards lift the work piece or lower the work piece downwards, prevent that other directions motion from disturbing the work piece and aligning with the thimble seat, the degree of convenience of measuring the work piece has further been improved. And the fixture block moves along the inclined plane through the movable block to realize reciprocating, the tank bottom of guide way is the plane at first, the movable block is located the tank bottom and can slide, and the movable block still is located the below of fixture block, the fixture block supports naturally and leans on the movable block, the lower terminal surface of fixture block is the inclined plane of slope, design like this just can be with the fixture block lifting when the movable block moves along the inclined plane, can control the fixture block and descend when the movable block moves in the opposite direction, the quality of work piece is great originally and is placed on the fixture block and make the total mass of fixture block increase, direct lifting or decline fixture block are comparatively difficult, this adjustment mechanism passes through the design of movable block, the vertical migration of fixture block is switched into the lateral shifting of movable block, thereby the convenient height of adjusting the work piece.

In the above-mentioned adjustable yaw meter, the adjusting mechanism includes a limiting seat located on the slide rail, the fixture block is in threaded connection with the upper end of the limiting seat, and the fixture block moves upward by rotating.

This is the second technical scheme of this scheme, what this technical scheme introduced is that on the spacing seat of fixture block threaded connection, realize adjusting the height of work piece through the circumferential direction fixture block, even design like this when placing the work piece that the quality is heavier on the fixture block, only need rotate the fixture block or use instrument rotate the fixture block just can adjust the height of work piece, also need not directly promote or descend in the vertical direction of fixture block, also the height of comparatively convenient regulation work piece, made things convenient for the measurement of work piece.

In the above adjustable yaw instrument, the bottom of the guide groove is provided with a raised rib, the bottom of the moving block is provided with a first sliding groove matched with the rib, and the moving block can slide along the rib.

Because the work piece quality of placing on the fixture block is great, the setting up of protruding muscle makes the removal orbit of removal obtain the restriction, and the protruding muscle can give the better side direction holding power of movable block with the cooperation of sliding one, makes it remove along protruding muscle, and stability is better.

In the above-mentioned adjustable yaw meter, the two side walls of the guide groove are provided with the guide portions, the two guide portions are arranged oppositely, and the clamping block is clamped between the two guide portions and can slide up and down along the guide portions.

The setting up of guide part makes the groove width of guide way can set up some wideers, carries out spacing direction to the fixture block by the guide part, and the displacement range that the effect of wideer guide way can let the movable block is wider to make the lifting scope of fixture block become bigger, thereby can use more sizes the work piece and the top on the thimble seat to the axis, adaptability is more extensive.

In the above-mentioned adjustable yaw meter, a sliding groove matched with the sliding rail is arranged at the bottom of the limiting seat, and a fixing bolt penetrating through the limiting seat, extending into the sliding groove and pressing against the side of the sliding rail is arranged on the limiting seat.

The limiting seat is arranged on the sliding rail in a sliding mode and can be located through the fixing bolt and the sliding rail after sliding to a position, the position of the clamping block, which abuts against the workpiece, can be adjusted through adjusting the position of the limiting seat to adapt to workpieces with different lengths, and further measurement of the workpieces is facilitated.

In the above-mentioned adjustable yaw meter, a push rod having the same direction as the first sliding groove is connected to the limiting seat through a thread, one end of the push rod is further axially fixed to the moving block, and the rotation of the push rod can drive the moving block to slide along the first sliding groove.

The moving block moves by rotating the push rod, and the push rod laterally extends into the guide groove or retreats from the guide groove to control the moving block to move, so that the height of the clamping block can be adjusted conveniently, and the workpiece can be measured conveniently. And the push rod passes through in spacing seat threaded connection, rotates the push rod and can control the push rod and stretch into or withdraw from the guide way, and the operation is very convenient like this to the regulation of fixture block height, further has made things convenient for the measurement of work piece.

In the adjustable yaw meter, a mounting hole is formed in the side portion of the moving block, an annular groove is formed in the end portion of the push rod, the end portion of the push rod extends into the mounting hole, and a screw extending into the annular groove is arranged on the moving block.

The push rod rotates the movable block and is not rotatory, so the push rod stretches into the movable block through the push rod and opens in the mounting hole of lateral part with the concrete fixed mode of movable block, then the push rod stretches into one of movable block and serves and set up the annular, twist on the movable block and stretch into the mounting hole and stretch into the screw in the annular and carry out the axial spacing to the push rod, when the push rod stimulates the movable block, the screw can support and restrict the push rod and extract from the mounting hole on the lateral wall of annular, design structure is ingenious like this, make the push rod can rotate movable block relatively, can realize moving up of fixture block through the push rod rotation and adjust the height of work piece, design great work piece measurement that has made things.

In the above adjustable yaw instrument, the top of the clamping block is provided with a V-shaped clamping groove.

When the shaft type workpiece is placed in the V-shaped clamping groove, the shaft type workpiece can be effectively prevented from rolling, the clamping block is prevented from being not aligned with the thimble seat well due to the fact that the workpiece rolls in the lifting process, the clamping groove can be well limited, when the workpiece is placed on the clamping block, the workpiece can be directly aligned with the clamping groove and placed into the clamping groove, adjustment in the direction is not needed, and the workpiece is further convenient to measure.

Compared with the prior art, the product has the advantages that:

1. the workpiece can be placed on the clamping block, then the height of the clamping block is adjusted through the adjusting mechanism, so that the workpiece is aligned with the ejector pin on the ejector pin base in a coaxial line mode, and in the design, the workpiece only needs to be carried onto the clamping block, and therefore the workpiece is greatly convenient to clamp and measure large workpieces.

2. The adjusting mechanism is arranged to enable the workpiece to be close to each other and clamp the workpiece after the workpiece is aligned with the ejector pins, and then the workpiece is separated from the workpiece by moving down the adjusting mechanism, so that the fixture block is designed to be free from interfering with the rotation measurement of the workpiece, and the workpiece can be very easily measured even if the size or the mass of the workpiece is large.

3. The adjusting mechanism switches the vertical movement of the clamping block into the transverse movement of the moving block through the design of the moving block, so that the height of a workpiece placed on the clamping block can be conveniently adjusted to a great extent, and the measurement of the workpiece is facilitated.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view of a portion of the components of the present invention;

FIG. 3 is a detail view of the cartridge of the present invention;

FIG. 4 is a detail view of the spacing block of the present invention;

FIG. 5 is a detail view of the traveling block of the present invention;

fig. 6 is a detail view of the push rod of the present invention.

In the figure, 1, a workbench; 11. a slide rail; 2. a thimble seat; 3. a clamping block; 31. a bevel; 32. a card slot; 4. a limiting seat; 41. a guide groove; 42. a rib is protruded; 43. a guide portion; 44. a chute; 5. a moving block; 51. a first sliding chute; 52. mounting holes; 6. fixing the bolt; 7. a push rod; 71. and a ring groove.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

Example one

As shown in fig. 1-6, the adjustable deflection instrument includes a workbench 1 having a slide rail 11 and two thimble seats 2, the two thimble seats 2 are both located on the slide rail 11 and are oppositely disposed, two fixture blocks 3 for placing a workpiece are slidably disposed on the slide rail 11 between the two thimble seats 2, the two fixture blocks 3 are respectively disposed by the two thimble seats 2, and an adjusting mechanism capable of adjusting the height of the fixture block 3 so that the workpiece placed on the fixture block 3 is aligned with the thimble on the thimble seat 2 coaxially is disposed between each fixture block 3 and the slide rail 11. The adjusting mechanism comprises a limiting seat 4 positioned on the sliding rail 11, a guide groove 41 is formed in the limiting seat 4, two guide parts 43 which are arranged oppositely are arranged on the inner side face of the groove opening of the guide groove 41, and the fixture block 3 is clamped between the two guide parts 43 and can slide up and down along the guide parts 43. The moving block 5 is disposed at the bottom of the guide groove 41, the bottom surface of the fixture block 3 is an inclined surface 31, and the moving block 5 abuts against the inclined surface 31 and can move up the fixture block 3 by moving along the inclined direction of the inclined surface 31. The top of the fixture block 3 is provided with a V-shaped fixture groove 32. When the shaft type workpiece is placed in the V-shaped clamping groove 32, the shaft type workpiece can be effectively prevented from rolling, the fixture block 3 is prevented from being misaligned with the thimble seat 2 due to the fact that the workpiece rolls in the lifting process, the clamping groove 32 can be well limited, when the workpiece is placed on the fixture block 3, the workpiece can be directly aligned with the clamping groove 32 and placed in the clamping groove, adjustment in the direction is not needed, and the workpiece is further convenient to measure.

This top needle file 2 of deflection appearance all sets up on the slide rail 11 of workstation 1, and two top needle file 2 homoenergetic slide along slide rail 11 and can stop on the position after the slip. Be equipped with fixture block 3 between two thimble seats 2, be equipped with adjustment mechanism on fixture block 3, adjustment mechanism can adjust the height of fixture block 3, we put the work piece on fixture block 3 through the work piece of holding up, then adjust fixture block 3's height through adjustment mechanism and realize aligning the work piece with the thimble coaxial line on the thimble seat 2, design like this we only need with the work piece carry on fixture block 3 can, can align the work piece with the thimble on two thimble seats 2 through the height of adjustment fixture block 3, set up great clamping that has made things convenient for the major possession work piece like this and measure. After the adjusting mechanism is arranged to align the ejector pins, the two ejector pin bases 2 are close to each other and clamp the workpiece, and then the workpiece is separated from the workpiece by moving down the adjusting mechanism, so that the fixture block 3 is designed to be free from interfering with the rotation measurement of the workpiece, so that the workpiece can be very easily measured even if the size or the mass of the workpiece is large. The fixture block 3 is located the inboard of guide way 41, and the fixture block 3 receives the spacing messenger fixture block 3 of the both sides cell wall of guide way 41 can only slide from top to bottom along guide way 41 from top to bottom, and it can not move about in other directions, designs like this when the work piece is placed on fixture block 3, and fixture block 3 can only upwards lifting work piece or lower the work piece downwards, prevents that other direction movements from disturbing the work piece and aligning with thimble seat 2, has further improved the convenience of measuring the work piece. And the fixture block 3 is moved up and down by the moving block 5 moving along the inclined surface 31, first the groove bottom of the guide groove 41 is a plane, the moving block 5 is located on the groove bottom and can slide, and the moving block 5 is also positioned below the fixture block 3, the fixture block 3 naturally abuts against the moving block 5, the lower end surface of the fixture block 3 is an inclined plane 31, design like this just can be with fixture block 3 lifting when the movable block 5 moves along inclined plane 31, steerable fixture block 3 descends when the movable block 5 moves in the opposite direction promptly, the quality of work piece is great to be placed on fixture block 3 originally and makes the total mass of fixture block 3 increase, direct lifting or descending fixture block 3 are comparatively difficult, this adjustment mechanism passes through the design of movable block 5, switch into the lateral shifting of movable block 5 with the vertical migration of fixture block 3, thereby the convenient height of adjusting the work piece of placing on fixture block 3 of very big degree has made things convenient for the measurement of work piece. The setting of guide part 43 makes the groove width of guide way 41 can set up some wideers, carries out spacing direction to fixture block 3 by guide part 43, and the removal scope that wider guide way 41's effect can let movable block 5 is wider to make the lifting scope of fixture block 3 become bigger, thereby can use the top on the work piece of more sizes and the thimble seat 2 to the axis, adaptability is more extensive.

The bottom of the guide groove 41 is provided with a raised rib 42, the bottom of the moving block 5 is provided with a first sliding groove 51 matched with the rib 42, and the moving block 5 can slide along the rib 42. The second sliding groove 44 is formed in the inclined surface 31 of the fixture block 3, the horizontal direction of the second sliding groove 44 is the same as the direction of the first sliding groove 51, only the second sliding groove 44 is formed in the inclined surface 31, the width of the second sliding groove 44 is increased along with the increase of the depth of the groove to form a notch, the upper end surface of the moving block 5 is an inclined surface 31 which is the same as the inclined direction of the inclined surface 31 of the fixture block 3, a matching portion which is similar to the outline of the second sliding groove 44 and can be embedded into the second sliding groove 44 is further arranged on the inclined surface 31, and the matching stability of the moving block 5 and the fixture block 3 is higher through the matching of the matching portion and the second sliding groove 44, so that. Because the work piece quality of placing on fixture block 3 is great, the setting up of protruding muscle 42 makes the removal orbit of removal obtain the restriction, and protruding muscle 42 and the cooperation of sliding one can give the better side direction holding power of movable block 5, make it remove along protruding muscle 42, and stability is better.

The bottom of the limiting seat 4 is provided with a sliding groove 44 matched with the sliding rail 11, and the limiting seat 4 is provided with a fixing bolt 6 which penetrates through the limiting seat 4, extends into the sliding groove 44 and is pressed against the side part of the sliding rail 11. The limiting seat 4 is arranged on the sliding rail 11 in a sliding mode, and can be located through the fixing bolt 6 and the sliding rail 11 after sliding to a position, the design can adjust the position, abutted to the workpiece, of the clamping block 3 to adapt to workpieces with different lengths by adjusting the position of the limiting seat 4, and further measurement of the workpieces is facilitated.

The limiting seat 4 is in threaded connection with a push rod 7 which faces towards the same direction as the first sliding groove 51, one end of the push rod 7 is axially fixed on the moving block 5, and the push rod 7 rotates to drive the moving block 5 to slide along the first sliding groove 51. The moving block 5 moves by rotating the push rod 7, and the push rod 7 laterally extends into the guide groove 41 or retreats from the guide groove 41 to control the moving block 5 to move, so that the height of the fixture block 3 can be adjusted greatly, and the measurement of a workpiece is facilitated. And the push rod 7 is in threaded connection with the limiting seat 4, and the push rod 7 can be controlled to extend into or withdraw from the guide groove 41 by rotating the push rod 7, so that the operation is very convenient for adjusting the height of the fixture block 3, and further the measurement of a workpiece is facilitated. The side of the moving block 5 is provided with a mounting hole 52, the end of the push rod 7 is provided with a ring groove 71, the end of the push rod 7 extends into the mounting hole 52, and the moving block 5 is provided with a screw extending into the ring groove 71. The push rod 7 rotates the moving block 5 and is not rotated, so the push rod 7 and the moving block 5 are fixed in a specific mode that the push rod 7 extends into the moving block 5 and is arranged in the mounting hole 52 of the side part, then the push rod 7 extends into one end in the moving block 5 and is provided with the annular groove 71, the screw which extends into the mounting hole 52 and extends into the annular groove 71 is screwed on the moving block 5 to axially limit the push rod 7, when the push rod 7 pulls the moving block 5, the screw can abut against the side wall of the annular groove 71 to limit the push rod 7 to be pulled out from the mounting hole 52, the structure is ingenious in design, the push rod 7 can rotate relative to the moving block 5, the upward movement of the clamping block 3 can be realized through the rotation of the push rod 7 to adjust the height of a workpiece.

Example two

The structure and principle of this embodiment are basically the same as those of the first embodiment, except that: the adjustment mechanism in this embodiment is including being located the spacing seat on the slide rail, and fixture block threaded connection realizes moving up at the upper end of spacing seat and fixture block through rotating. This is the second technical scheme of this present case, what this technical scheme introduced is that on 3 threaded connection of fixture block 4, realize adjusting the height of fixture block 3 through circumferential rotation fixture block 3, even design like this when placing the work piece that the quality is heavier on fixture block 3, only need rotate fixture block 3 or use tool rotate fixture block 3 just can adjust the height of work piece, also need not directly promote or descend in the vertical direction of fixture block 3, also the height of comparatively convenient regulation work piece, made things convenient for the measurement of work piece.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Claims

1. The utility model provides an adjustable deflection appearance, is including workstation (1) and two thimble seats (2) that have slide rail (11), two thimble seat (2) all are located slide rail (11) and set up relatively, its characterized in that, it is provided with at least one fixture block (3) that are used for placing the work piece to lie in on slide rail (11) and slide between two thimble seats (2), be equipped with between fixture block (3) and slide rail (11) and adjust fixture block (3) height and make the adjustment mechanism who places the work piece on fixture block (3) and the coaxial line alignment of thimble on thimble seat (2).

2. The adjustable yaw instrument according to claim 1, wherein the adjusting mechanism comprises a limiting seat (4) located on the sliding rail (11), a guide groove (41) is formed in the limiting seat (4), the fixture block (3) is located inside the guide groove (41) and can slide up and down along the guide groove (41), a moving block (5) is arranged at the bottom of the guide groove (41), the bottom surface of the fixture block (3) is an inclined plane (31), and the moving block (5) abuts against the inclined plane (31) and can move up the fixture block (3) by moving along the inclined direction of the inclined plane (31).

3. The adjustable yaw meter according to claim 1, wherein the adjusting mechanism comprises a limiting seat (4) located on the sliding rail (11), the clamping block (3) is in threaded connection with an upper end portion of the limiting seat (4), and the clamping block (3) moves upwards through rotation.

4. The adjustable yaw meter according to claim 2, wherein a raised rib (42) is provided at the bottom of the guide groove (41), a first sliding groove (51) matched with the rib (42) is provided at the bottom of the moving block (5), and the moving block (5) can slide along the rib (42).

5. The adjustable yaw meter according to claim 4, wherein the guide portions (43) are disposed on both side walls of the guide groove (41), the two guide portions (43) are disposed opposite to each other, and the latch (3) is disposed between the two guide portions (43) and can slide up and down along the guide portions (43).

6. The adjustable yaw meter according to claim 4 or 5, characterized in that a sliding groove (44) which is matched with the sliding rail (11) is formed at the bottom of the limiting seat (4), and a fixing bolt (6) which penetrates through the limiting seat (4) and extends into the sliding groove (44) and is pressed against the side of the sliding rail (11) is arranged on the limiting seat (4).

7. The adjustable yaw meter according to claim 6, wherein a push rod (7) facing the same direction as the first sliding groove (51) is connected to the limiting seat (4) in a threaded manner, one end of the push rod (7) is further axially fixed to the moving block (5), and the push rod (7) can rotate to drive the moving block (5) to slide along the first sliding groove (51).

8. The adjustable yaw meter according to claim 7, wherein a mounting hole (52) is formed in a side portion of the moving block (5), a ring groove (71) is formed in an end portion of the push rod (7), the end portion of the push rod (7) extends into the mounting hole (52), and a screw extending into the ring groove (71) is arranged on the moving block (5).

9. The adjustable yaw meter according to claim 8, characterized in that the top of the block (3) has a V-shaped notch (32).