CN216682396U - Books positioner of books paper cutter - Google Patents

Abstract

The utility model discloses a book positioning device of a book paper cutting machine, which comprises a book clamping device, wherein the book clamping device is provided with a fixed clamping plate and a movable clamping plate which are used for clamping a book to be cut, the upper part of the movable clamping plate is connected with a power source for driving the movable clamping plate to move up and down, the fixed clamping plate is positioned at a round hole part of a workbench, the bottom of the fixed clamping plate is connected with a rotating shaft for driving the fixed clamping plate to rotate around a vertical axis through a flange, a vertical plate for stopping the back of the book to be cut is arranged at the rear part of the book clamping device, and a telescopic positioning pin is arranged at the side part of the workbench surface. According to the positioning device of the book paper cutter, after a book to be cut is positioned once, the book does not need to be taken out and pressed and positioned again, so that multi-surface cutting can be completed, the structure is simple, time and labor are saved, the cutting power requirement is lower, and the maintenance cost is low; the selling price of the composite cutter book paper cutter is far lower than that of a composite cutter book paper cutter.

Description

Books positioner of books paper cutter

Technical Field

The utility model relates to a paper cutter, in particular to a book positioning device of a book paper cutter.

Background

The book manufacturing comprises the production processes of white paper cutting, printing, binding, volume forming and the like. After binding, the redundant parts of the other three edges of the books except the book backs need to be cut so that the sizes of the books are consistent and the edges are flush.

Traditional books paper cutter, after cutting the one side, need the manual work to turn to, the adjustment size cuts the another side again, and manual work turns to once more, and the adjustment size could accomplish the trilateral edge of this book and cuts. A book edge trimmer according to application No. 201721331046.7, comprising an operating table 1, a conveyor 2 arranged on the operating table 1, a clamping device 3 arranged above the conveyor 2 for pre-clamping a book 6, a cutter assembly 4 arranged on one side of the conveyor 2, and a drive 5 for driving the cutter assembly 4 to cut the edge of the book. Before the cutter assembly 4 cuts the book 6, the piston shaft 321 of the pneumatic cylinder 32 may abut on the sidewall of the movable clamp 312 and push the movable clamp 312 to translate toward the fixed clamp 311 against the elastic force of the spring 314 to clamp the book 6 firmly. When the cutting action is completed, the piston shaft 321 is retracted to be separated from the movable clamping plate 312, and the movable clamping plate 312 can be reset under the elastic force of the spring 314. The book cutting machine with the single-cutter structure is time-consuming, labor-consuming and low in efficiency.

As an improvement, a three-side trimmer having a composite cutter has been designed to cut three edges of a book in synchronization. However, the three-side book trimming machine with the structure has a complex structure, the requirement on trimming power is high (more than 5 times higher than that of a single cutter), the cutter is difficult to machine, and after the blade is sharpened by a blunt sharpener, a professional is required to install and debug the cutter, so that the maintenance cost is high; because three sides are cut synchronously, the cut book can be clamped between the cutters at two sides, and the book needs to be ejected out by a special device, so that the cutting surface of the book is inevitably extruded, and the levelness of the cutting surface is influenced; the selling price is more than 10 times higher than that of a single cutter.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a positioning device of a book paper cutter, after a book to be cut is positioned for one time, the book does not need to be taken out and pressed and positioned again, the book to be cut can be sequentially transferred to a cutter of a conventional single-side cutting device to be cut through mechanical steering positioning, multi-surface cutting is completed, the positioning device is simple in structure, time-saving and labor-saving, the cutting power requirement is lower, the cutter is a flat-plate universal cutter, no professional is needed to install and debug the cutter after a blade is sharpened, and the maintenance cost is low; and the books after cutting need not special device and pushes out the books, this just avoided the hidden danger that extrudes the cutting face of books, influences the parallel and level degree of cutting face, and its price is far less than the price of compound cutter books paper cutter.

In order to achieve the purpose, the utility model adopts the following technical scheme:

the utility model provides a books positioner of books paper cutter, includes books clamping device, books clamping device has and is used for pressing from both sides the solid fixed splint and the movable clamp plate that wait to cut books, and movable clamp plate's upper portion is connected with its power supply that reciprocates of drive, gu fixed splint is located the round hole portion of workstation, gu fixed splint's bottom is passed through the flange and is connected around its rotatory rotation axis of vertical axis with the drive, is equipped with the riser that is used for the backstop to wait to cut the back of the book of books at books clamping device's rear portion, is equipped with flexible locating pin at workstation mesa side.

When the book back of the book to be cut abuts against the inner side face of the vertical plate, and the edge of the book to be cut on the adjacent side of the book back abuts against the telescopic positioning pin, the rotation axis of the book to be cut coincides with the vertical axis, and the distances between the rotation axis and the three edges to be cut are equal.

The upper surface of the fixed clamping plate is flush with the table top of the workbench.

Compared with the prior art, the utility model has the beneficial effects that: by adopting the technical scheme, the fixed clamp plate is positioned at the circular hole part of the workbench, the bottom of the fixed clamp plate is connected with the rotating shaft which drives the fixed clamp plate to rotate around the vertical axis through the flange, the rear part of the book clamping device is provided with the vertical plate for stopping the book back of the book to be cut, the side part of the workbench table surface is provided with the telescopic positioning pin, when the book back of the book to be cut is abutted against the inner side surface of the vertical plate and the edge to be cut of the adjacent side of the book to be cut and the book to be cut is abutted against the telescopic positioning pin, the book to be cut which is pressed by the book clamping device can rotate to a preset angle through the rotating shaft driving the book clamping device, the edge to be cut of the book to be cut can be rotated to the cutter for cutting, after the book to be cut is once positioned, the book to be cut can be sequentially transferred to the cutter of the conventional single-side cutting device without taking out the book for pressing and positioning again, the novel knife edge sharpening machine is simple in structure, time-saving, labor-saving, low in cutting power requirement, flat-plate universal, low in maintenance cost and free of installation and debugging of the knife by professionals after the knife edge is sharpened. The book paper cutter breaks through the traditional concept and creatively invents a book paper cutter which rotates and cuts by the rotation axis of the book to be cut.

The further beneficial effects are that: because the book positioning device enables the rotation axis of the book to be cut to coincide with the rotating vertical axis of the fixed clamp plate when the back of the book to be cut abuts against the inner side surface of the vertical plate and the edge of the book to be cut on the side adjacent to the back of the book abuts against the telescopic positioning pin, and the distances between the rotation axis and the three edges to be cut are equal, the structure can respectively rotate the three edges to be cut of the book to be cut to the cutter of the book single-edge cutting device for cutting, the distance between the cutter and the vertical axis is preset, the size of the redundant edge to be cut of the three edges to be cut can be preset, compared with the three-edge book cutter of the composite cutter in the background technology, the structure is simple, time and labor are saved, the cutting power requirement is lower, the cutter is a flat universal cutter, no professional is needed to install and debug the cutter after the cutter is sharpened, and the maintenance cost is low, the books after cutting need not special device and pushes out the books, this just has avoided the hidden danger that extrudes the cutting face of books, influences the parallel and level degree of cutting face, and its price is far less than the price of compound cutter books paper cutter.

Drawings

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

FIG. 2 is a top view of FIG. 1;

FIG. 3 is a bottom view of FIG. 1;

FIG. 4 is a left side view of FIG. 1;

FIG. 5 is a schematic illustration of the disassembled structure of FIG. 1;

fig. 6 is a schematic view of the book clamping device of fig. 5 in a disassembled configuration;

FIG. 7 is a schematic perspective view of the book single-edge cutting device of the present invention when a book to be cut is placed therein;

FIG. 8 is a front view of FIG. 7;

FIG. 9 is a top view of FIG. 8;

fig. 10 is a schematic view of a B5 size book to be cut;

FIG. 11 is a schematic view of a book size A4 to be cut;

FIG. 12 is a schematic view of a book size B4 to be cut;

FIG. 13 is a schematic diagram of the electrical connections of the control apparatus of the present invention when the STM32F103RBT6 control chip is preferred.

The technical features represented by the reference numerals in the figures are as follows:

the book to be cut 01, a rotating axis 01-1, a book clamping device 1, a motor I1-1, a motor bracket 1-2, a screw rod 1-5, a screw rod mounting bracket 1-6, a fixed splint 1-7-1, a vertical plate 1-7-2, a mounting plate 1-7-3, a linear bearing 1-8, a guide rod 1-9, a nut sleeve 1-10, a movable splint 1-11, a book single-edge cutting device 02, a cutter 02-1, a paper cutting motor 02-2, a paper pressing code disc detection optocoupler 02-3, a paper pressing motor 02-4, a paper pressing upper limit proximity switch 02-5, a paper cutting lower limit proximity switch 02-6, a travel switch 2, a vertical axis 03, a workbench 3, a circular hole 3-1, a mounting cushion block 4, a rotating shaft 5 and a thrust bearing 6, the device comprises a rotary driving device mounting plate 07, a motor mounting support 8, a synchronous belt 9, a synchronous belt pulley I10, a motor II 11, a book positioning electromagnet support 12, a book positioning electromagnet 13, a telescopic positioning pin 13-1, a rotation angle locking electromagnet mounting support 14, a rotation angle locking electromagnet 15, a rotating bearing base 16, a synchronous belt pulley II 17, a semicircular sheet 18, an inductive switch support 19 and a semicircular sheet optical coupler switch 20.

Detailed Description

In order to make the technical solution of the present invention clearer, the present invention will be described in detail with reference to fig. 1 to 13. It should be understood that the detailed description and specific examples, while indicating the scope of the utility model, are intended for purposes of illustration only and are not intended to limit the scope of the utility model.

Example 1:

the utility model relates to a book positioning device of a book paper cutting machine, which comprises a book clamping device 1, wherein the book clamping device 1 is provided with a fixed clamping plate 1-7-1 and a movable clamping plate 1-11 for clamping a book 01 to be cut, the upper part of the movable clamping plate 1-11 is connected with a power source for driving the movable clamping plate to move up and down, the fixed clamping plate 1-7-1 is positioned at the round hole 3-1 part of a workbench 3, the bottom of the fixed clamping plate 1-7-1 is connected with a rotating shaft 5 for driving the fixed clamping plate to rotate around a vertical axis 03 through a flange, the rear part of the book clamping device 1 is provided with a vertical plate 1-7-2 for stopping the book back of the book 01 to be cut, and the side part of the table top of the workbench 3 is provided with a telescopic positioning pin 13-1.

Preferably, when the book back of the book 01 to be cut abuts against the inner side face of the vertical plate 1-7-2, and the edge of the book 01 to be cut on the side adjacent to the book back abuts against the telescopic positioning pin 13-1, the rotation axis 01-1 of the book 01 to be cut coincides with the vertical axis 03, and the distances from the rotation axis 01-1 to the three edges to be cut are equal.

Preferably, the upper surface of the fixed clamping plate 1-7-1 is flush with the table top of the worktable 3.

Example 2:

a book paper cutting machine using the book positioning device comprises a workbench 3, a book clamping device 1 arranged on the workbench 3, a book positioning device, a book unilateral cutting device 02 and a rotary driving device for driving the book clamping device 1 to rotate around a vertical axis 03, when a book 01 to be cut is positioned on the book clamping device 1 through the book positioning device, a rotary axis 01-1 of the book 01 to be cut is superposed with the vertical axis 03, the distances between the rotary axis 01-1 and the three edges to be cut are equal, in the state, the control device controls the book clamping device 1 to clamp the book 01 to be cut, and then controls the rotary driving device to rotate by a preset angle, so that the clamping device 1 is driven to rotate by corresponding angles around the vertical axis 03, and the three edges to be cut of the book 01 to be cut are respectively rotated to a cutter 02 of the book unilateral cutting device 02 And (1) cutting. The book single-side cutting device 02 is designed in the prior art, the book single-side cutting device 02 can be arranged on the rear side of the workbench 3, the cutter 02-1 of the book single-side cutting device 02 is driven by the paper cutting motor 02-2, the book single-side cutting device 02 further comprises a pressing plate driven by the paper pressing motor 02-4 and used for pressing the edge to be cut, when a certain edge to be cut rotates to the cutter 02-1, the edge to be cut is parallel to the cutter 02-1, the control device controls the paper pressing motor to rotate so as to drive the pressing plate to press the edge to be cut tightly, and then the control device controls the paper cutting motor to rotate so as to drive the cutter 02-1 to cut redundant edges of the edge to be cut; because the distances from the rotating axis 01-1 of the book 01 to be cut to the three edges to be cut are equal, the distance from the cutter 02-1 to the vertical axis 03 is preset, and the sizes of the redundant edges to be cut of the three edges to be cut can be preset. In order to improve the safety of the operation, a safety photoelectric detection device, such as an infrared light sensing device capable of sensing a human body, may be further provided, and the arm may be pressed or cut only after leaving the dangerous area, which is also the prior art and is not described.

Preferably, the book positioning device comprises the vertical plate 1-7-2 for stopping the book back of the book 01 to be cut and a telescopic positioning pin 13-1 arranged at the side part of the table top of the workbench 3. When the book back of the book 01 to be cut abuts against the inner side face of the vertical plate 1-7-2 and the edge of the book 01 to be cut on the side adjacent to the book back abuts against the telescopic positioning pin 13-1, the positioning is completed, in this state, the book 01 to be cut is positioned by the vertical plate 1-7-2 and the telescopic positioning pin 13-1, and the rotation axis 01-1 is coincident with the vertical axis 03. And pressing a pressing key, and starting a motor I1-1 by the control device to rotate forwards so that the book clamping device 1 clamps the book 01 to be cut. Preferably, the telescopic positioning pin 13-1 is driven by a book positioning electromagnet 13, the book positioning electromagnet 13 is fixed below the table top of the workbench 3 through a book positioning electromagnet support 12, the upper end of the telescopic positioning pin 13-1 penetrates through a through hole of the table top and is higher than the table top, when the book positioning electromagnet 13 is electrified and attracted, the positioning electromagnet 13 overcomes the elastic force for supporting the telescopic positioning pin 13-1 and attracts the positioning electromagnet 13 downwards, so that the upper end of the telescopic positioning pin 13-1 is lower than the table top, and the rotation of the book 01 to be cut is not influenced. The operation of the motor is controlled according to the electrical signal of the sensor (the travel switch), which is the prior art in the field and will not be described in detail.

Preferably, the clamping device 1 comprises: the book cutting machine comprises a fixed clamping plate 1-7-1 and a movable clamping plate 1-11, wherein the movable clamping plate 1-11 is driven by a power source (which can be a motor, an air cylinder or an oil cylinder) to move towards the fixed clamping plate 1-7-1 so as to clamp a book 01 to be cut between the fixed clamping plate 1-7-1 and the movable clamping plate 1-11. . Preferably, the fixed splint 1-7-1 is fixedly connected with the mounting plate 1-7-3 above the fixed splint through a vertical plate 1-7-2 at the rear end of the fixed splint, the power source is a motor I1-1 arranged on a motor bracket 1-2, the motor bracket 1-2 is arranged on the mounting plate 1-7-3 through a screw rod mounting bracket 1-6, a rotating shaft of the motor I1-1 is in transmission connection with the upper end part of a screw rod 1-5, the screw rod 1-5 is in threaded connection with a screw nut sleeve 1-10, the lower end of the screw nut sleeve 1-10 is arranged on a movable splint 1-11, linear bearings 1-8 are arranged on two sides of the mounting plate 1-7-3, guide rods 1-9 fixed on two sides of the movable splint 1-11 are arranged in the inner holes of the corresponding linear bearings 1-8 in a sliding manner, the screw rod 1-5 is driven to rotate forwards or backwards through the forward rotation or the backward rotation of the motor 1-1, the movable clamping plate 1-11 is driven to move up and down through the nut sleeve 1-10 so as to press or loosen the book 01 to be cut, and the guide rod 1-9 moves up and down in the linear bearing 1-8 so as to prevent the movable clamping plate 1-11 from deviating when moving up and down. Whether the book 01 to be cut is clamped by the clamping device 1 or not can be finished by installing a pressure sensor or detecting the change of the current of the motor 1-1 (when the book 01 to be cut is clamped by the clamping device 1, the working current of the motor stops), and after the book 01 to be cut is clamped by the clamping device 1, the control device controls the motor to stop.

Preferably, the rotation driving device includes: a rotating shaft 5 which is arranged at the lower part of the workbench 3 and is driven by a motor II 11 is provided with a round hole 3-1 with a notch (the notch is arranged for taking out the cut books more conveniently), and the upper end of the rotating shaft 5 is connected with the bottom of the fixed splint 1-7-1 through a flange at the round hole 3-1 part. Preferably, the upper surface of the fixing splint 1-7-1 is flush with the table top, so that the bottom surface of the book 01 to be cut is kept horizontal by the upper surface of the fixing splint 1-7-1 and the table top, and the fixing splint 1-7-1 rotates at the circular hole 3-1, thus facilitating the positioning, rotation and cutting of the book 01 to be cut. Preferably, the rotary driving device is provided with a rotary driving device mounting plate 07, the rotary driving device mounting plate 07 is mounted below the table top of the workbench 3, a mounting cushion block 4 can be further arranged between the rotary driving device mounting plate 07 and the table top, a rotary bearing seat 16 is arranged below the middle part of the rotary driving device mounting plate 07, a thrust bearing 6 for supporting the rotary shaft 5 is mounted in the rotary bearing seat 16, a synchronous pulley II 17 is mounted at the lower part of the rotary shaft 5 penetrating through the rotary bearing seat 16, a synchronous pulley I10 is mounted on the rotary shaft of the motor II 11, the synchronous pulley I10 is in transmission connection with the synchronous pulley II 17 through a synchronous belt 9, and the motor II 11 is fixed below one side of the rotary driving device mounting plate 07 through a motor mounting bracket 8. Preferably, a rotation angle locking electromagnet 15 can be further installed on the lower surface of the other side of the rotation driving device installation plate 07, and the rotation angle locking electromagnet 15 is installed on the rotation driving device installation plate 07 through a rotation angle locking electromagnet installation bracket 14; the function of the rotation angle locking electromagnet 15 is as follows: in the initial state, a movable ejector pin of the rotation angle locking electromagnet 15 abuts against the bottom of the fixed splint 1-7-1 so that the fixed splint cannot rotate; when the fixed splint 1-7-1 needs to rotate, the control device controls the rotating angle to lock the electromagnet 15 for suction, and the movable ejector pin is separated from the bottom of the fixed splint 1-7-1; when a certain edge to be cut rotates to the position of the cutter 02-1, the control device controls the rotating angle to lock the electromagnet 15 to be powered off, the rotating angle to lock the electromagnet 15 is loosened, and the movable ejector pin abuts against the bottom of the fixed clamping plate 1-7-1 under the action of the elastic force to prevent the fixed clamping plate from rotating, so that the book single-side cutting device 02 can cut better.

In an initial state, the vertical plate 1-7-2 of the clamping device 1 is opposite to the opposite cutter 02-1, the inner side face of the vertical plate 1-7-2 is parallel to the cutter 02-1, the opening of the clamping device 1 is forward, and the movable clamping plate 1-11 of the clamping device 1 is positioned at the upper limit position, so that books 01 to be cut can be conveniently placed in the clamping device. Preferably, the second motor 11 can be a commercially available stepping motor, and is preferably a stepping motor with a grating processor at the tail, so that the steering positioning accuracy can be improved. The control of the rotation of the stepping motor to a set angle is a prior art in the field and is not described in detail.

The control device is provided with a reset key, and when the reset key is pressed down, the control device controls the clamping device 1 to enter an initial state.

As preferred, can set up preferred resetting means, it is including setting up in the semicircle piece 18 of rotation axis 5 lower extreme and setting up the semicircle piece opto-coupler switch 20 on inductive switch support 19, when semicircle piece 18 rotated to semicircle piece opto-coupler switch 20 top, semicircle piece opto-coupler switch 20 action sent corresponding signal of telecommunication to the controller, when semicircle piece 18 rotated from semicircle piece opto-coupler switch 20 top, semicircle piece opto-coupler switch 20 closed, controlling means can judge from this whether clamping device 1 is located initial position.

In the technical scheme, the preferable working steps are as follows:

firstly, the method comprises the following steps: and when the starting key is pressed down, the control device starts to work after receiving a voltage signal, the semi-circular plate 18 below the second synchronous belt wheel 17 connected with the second motor 11 (adopting a servo motor) rotates to the semi-circular plate optical coupling switch 20, and then the clamping device 1 stops at the initial position.

II, secondly: placing a book 01 to be cut into a clamping device 1, pressing down a pressing key when the book back of the book 01 to be cut abuts against a vertical plate 1-7-2 and simultaneously the edge of the book 01 to be cut on one side abuts against a telescopic positioning pin 13-1, starting a motor 1-1 to rotate forward by a control device so that the book 01 to be cut is clamped by the book clamping device 1, increasing the working current of the motor 1-1 after the clamping device 1 clamps the book, triggering a positioning electromagnet 13 to attract the telescopic positioning pin 13-1 downwards by the control device according to a feedback signal so that the upper end of the telescopic positioning pin 13-1 is lower than a table board, controlling a rotating angle to lock an electromagnet 15 to suck the book, separating a movable top pin from the bottom of a fixed clamping plate 1-7-1, controlling a motor II 11 (adopting a servo motor) to rotate for 90 degrees by the control device, and then operating a book single-side cutting device 02, after the first knife is finished, a feedback signal is transmitted to the stepping motor to rotate by 90 degrees again, then the book single-edge cutting device 02 works, the paper cutter finishes cutting by the second knife, after the third knife is repeated, the stepping motor reverses by 270 degrees to recover, and the clamping device 1 is loosened to take out the cut book.

Preferably, the two sides of the vertical plate 1-7-2 are provided with the travel switches 2, when the book back of the book 01 to be cut abuts against the vertical plate 1-7-2, the travel switches 2 on the two sides of the vertical plate 1-7-2 are pressed and closed by the book back, the two travel switches 2 send electric signals to the control device, and the control device receives the electric signals for closing the two travel switches 2, so that the motor 1-1 is started to rotate forwards, and the book clamping device 1 clamps the book 01 to be cut.

In order to increase the degree of automation of the book cutter, a commercially available control chip may be preferred as the control component of the control device. For the part related to automatic control in this embodiment, the realization of the control function can depend on a control chip of model STM32F103RBT6, and an ARM CorteX3 system chip of an intentional semiconductor is selected as a main control chip of the system, so it is not difficult to find that the electric control realization of this system belongs to the prior art, and a person skilled in the art can realize the control according to the prior art, and certainly, other auxiliary controls in this system can also be realized by adopting chips.

Certainly, other functional modules connected with the main control chip are necessarily involved in the system, such as a communication module, which adopts serial port communication and is used for data transmission interaction between running data of each device in the system and an operation screen; the stepping motor control module is used for sending pulses and controlling the rotation of the stepping motor; the strong current output module is used for controlling the running of the alternating current motor; the input detection module is used for converting the sensor signal into a chip signal; and the power supply conversion module is used for converting the input power supply into a power supply voltage of 12V, 9V, 5V, 3.3V and the like required by the control system. The control circuits of the modules are mature technologies in the prior art, and are connected with the circuit of the main control chip and are mature technologies of integrated circuits. Referring to fig. 13, the connection relationship between each electrical element and the chip in the system is illustrated, and those skilled in the art can implement the connection relationship by combining the prior art, so detailed description is omitted.

Claims (3)

1. A book positioning device of a book paper cutter comprises a book clamping device (1), wherein the book clamping device (1) is provided with a fixed clamping plate (1-7-1) and a movable clamping plate (1-11) which are used for clamping a book (01) to be cut, the upper part of the movable clamping plate (1-11) is connected with a power source which drives the movable clamping plate to move up and down, and the book positioning device is characterized in that: the book cutting device is characterized in that the fixed clamp plate (1-7-1) is located at the round hole (3-1) of the workbench (3), the bottom of the fixed clamp plate (1-7-1) is connected with a rotating shaft (5) which drives the fixed clamp plate to rotate around a vertical axis (03) through a flange, a vertical plate (1-7-2) which is used for stopping the back of a book (01) to be cut is arranged at the rear part of the book clamping device (1), and a telescopic positioning pin (13-1) is arranged on the side part of the table top of the workbench (3).

2. The book positioning device of the book cutter according to claim 1, characterized in that: when the book back of the book (01) to be cut abuts against the inner side face of the vertical plate (1-7-2), and the edge of the book (01) to be cut adjacent to the book back abuts against the telescopic positioning pin 13-1, the rotating axis (01-1) of the book (01) to be cut coincides with the vertical axis (03), and the distances between the rotating axis (01-1) and the three edges to be cut are equal.

3. The book positioning device of the book cutter according to claim 1 or 2, characterized in that: the upper surface of the fixed splint (1-7-1) is flush with the table surface of the workbench (3).

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