US3650133A - Longitudinal carriage drive for co-ordinates tables in machine tools, particularly punching machines - Google Patents

Longitudinal carriage drive for co-ordinates tables in machine tools, particularly punching machines Download PDF

Info

Publication number
US3650133A
US3650133A US3650133DA US3650133A US 3650133 A US3650133 A US 3650133A US 3650133D A US3650133D A US 3650133DA US 3650133 A US3650133 A US 3650133A
Authority
US
United States
Prior art keywords
longitudinal carriage
longitudinal
tables
drive
machine
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
Inventor
Walter Bredow
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
C Behrens AG
Original Assignee
C Behrens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by C Behrens AG filed Critical C Behrens AG
Application granted granted Critical
Publication of US3650133A publication Critical patent/US3650133A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D28/00—Shaping by press-cutting; Perforating
    • B21D28/24—Perforating, i.e. punching holes
    • B21D28/26—Perforating, i.e. punching holes in sheets or flat parts
    • B21D28/265—Perforating, i.e. punching holes in sheets or flat parts with relative movement of sheet and tools enabling the punching of holes in predetermined locations of the sheet, e.g. holes punching with template
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T83/00—Cutting
    • Y10T83/647—With means to convey work relative to tool station
    • Y10T83/654—With work-constraining means on work conveyor [i.e., "work-carrier"]

Definitions

  • Stems ABSTRACT A longitudinal carriage drive for co-ordinates tables in machine tools for impelling the carriages on co-ordinates tables, particularly the longitudinal carriage, with the transverse carriage moving thereupon transversely to the longitudinal axis of the machine, and to the material to be punched held fast thereto, in which a power transmission by two screwthreaded spindles is provided to the left and right of the center of the machine, which receive their drive synchronously from a motor arranged at about the middle of the table.
  • This invention relates to the longitudinal carriage drive for coordinates tables in machine tools, particularly punching or stamping machines, for the transporting of the carriages on the coordinates tables, particularly of the longitudinal carriage, with the transverse carriage moving thereupon transversely to the longitudinal axis of the machine, and with the material to be punched or stamped held fast thereon, with power-transmission by screw-threaded spindles.
  • the invention is particularly advantageous with
  • the invention consists in the feature that to the left and right of the center of the machine two threaded spindles are arranged, which receive their drive synchronously from a common driving motor arranged on about the center of the table. It has been found particularly advantageous in this case to employ ball rotary spindles, which, in consequence of the initial stress of the ball bearings, ensure running practically free from backlash in the transmission of the driving forces. The adoption of such spindles also has the advantage that the coefficient of friction of the driving spindle is completely invariable.
  • the driving motor and the power-transmitting means between this motor and the threaded spindles are arranged symmetrically about the Y-axis of the longitudinal carriage.
  • Such an arrangement provides particularly advantageous presumptions for the accommodation of monitoring appliances, which already show any change of equilibrium between the drives, or even cut out the drive altogether.
  • toothed belt gears are preferred.
  • Such gears provide lightweight steel-armored expansion-free toothed belts, which transmit the driving forces positively and without slipping.
  • toothed belts are associated electrical measured-value receivers, for instance electric generators, which, upon disturbance of the state of equilibrium, switch off the drive. It is also possible to associate light cabinets with the toothed belts.
  • electrical measured-value receivers for instance electric generators
  • light cabinets with the toothed belts.
  • the driving means that are to meet the highest requirements as regards accuracy must remain protected against any disturbance in operation and against overstressing.
  • the arrangement of the monitoring appliances is promoted by the same forces and the same speeds having to occur in each case at the same points in the symmetrically arranged driving system. Any change in the state of equilibrium gives rise to a response from the monitoring appliances, so that disturbances can be directly avoided.
  • a considerable improvement in the accuracy of working of punching machines is also effected, which can thereby be employed in machining operations which require particularly high accuracy.
  • FIG. 1 shows a coordinates table in side elevation
  • FIG. 2 shows a plan view of the coordinates table
  • FIG. 3 shows the coordinates table in front elevation.
  • longitudinal girders 2 and 2' Upon underpart 1 of the table are arranged, to right and left (FIG. 3), longitudinal girders 2 and 2' for the accommodation and guidance of a longitudinal carriage. To the longitudinal girders 2 and 2' are bolted guiding rails 3 and supporting rails 4, upon which the complete longitudinal carriage is guided and supported, respectively.
  • the longitudinal carriage consists essentially of a cross girder 5, with a left-hand roller shoe 6 and a right-hand roller shoe 6', in which supporting rollers 7 and lateral guiding rollers 8 are journaled.
  • roller shoes 6 and 6' To the underside of the roller shoes 6 and 6' are secured holders 9 and 9' for the accommodation of the ball rotary nuts of ball rotary spindles 10, serving advantageously as a drive, for driving the longitudinal carriage; and upon these roller shoes are secured supporting plates 11, 11 for the material to be punched. These bearing surfaces thus accompany the movement of the iongitudinal carriage.
  • the ball rotary spindles 10 are axially mounted in bearing shields 12 and 12 and bearings 13 and 13, which are connected fast, in front and behind, with the longitudinal girders 2 and 2' respectively.
  • a ball rotary nut 19 on the spindle 17 is connected on the other side by its holder with the transverse carriage 18, and to the latter in turn is bolted a clamping rail 20.
  • workpiece-stretchers 21 three in number, for example, are displaceably secured.
  • material 22 to be punched consisting of a plate, represented by dot-and-dash lines, for travelling between the upper and lower turntables of rotary punches.
  • the axial positions of the bearings of these turntables are indicated at 23, and that of one of the tool stations at 24.
  • transverse roller'guided punch-material supporting rails 25 which, upon the punched material being removed towards the left (see FIG. 1), are guided over a descending guiding curve 26 into an open space between the underpart l of the table and the transverse girder 5 of the longitudinal carriage and are there caught up.
  • Guiding and connecting chains 27 for the punched-material rails 25 are pivotally connected by their right-hand ends 28 and 28' with the punched-material supporting plates 11 and 11, and by spring-equipped tension rods 29, in the bearing shields l2, 12', which are secured, under tension, to the front ends of the longitudinal girders 2 and 2'.
  • the longitudinal carriage drive by the ball rotary spindles 10 is effected completely without slip and with the spindles turning synchronously, by a driving motor 41, which is connected by a bearing shield 40 with the front wall of the underpart 1 of the table, with the aid of toothed belts 42, by way of corresponding toothed disc wheels 43.
  • a driving motor 41 which is connected by a bearing shield 40 with the front wall of the underpart 1 of the table, with the aid of toothed belts 42, by way of corresponding toothed disc wheels 43.
  • the power transmitting means between the motor 41 and the spindles are symmetrically arranged about Y-axis of the longitudinal carriage.
  • measured-value receivers for instance electrical generators 44, or, optionally, light sensors 45, which respond to irregular running of the power-transmitting means, or to breakage of a toothed belt, and thereby preclude any injury to the drive, and to the guidance of the longitudinal carriage, by interrupting the drive.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Punching Or Piercing (AREA)
  • Press Drives And Press Lines (AREA)
  • Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)

Abstract

A longitudinal carriage drive for co-ordinates tables in machine tools for impelling the carriages on co-ordinates tables, particularly the longitudinal carriage, with the transverse carriage moving thereupon transversely to the longitudinal axis of the machine, and to the material to be punched held fast thereto, in which a power transmission by two screw-threaded spindles is provided to the left and right of the center of the machine, which receive their drive synchronously from a motor arranged at about the middle of the table.

Description

United States Patent Bredow [451 Mar. 21, 1972 [54] LONGITUDINAL CARRIAGE DRIVE FOR CO-ORDINATES TABLES IN MACHINE TOOLS, PARTICULARLY PUNCHING MACHINES [72] Inventor: Walter Bredow, Alfeld an der Leine,
Germany [73] Assignee: C. Behrens Aktlengesellschait,
sl n sr. .i i9 many [22] Filed: Sept. 3, 1969 [21] Appl. No.: 854,851
[30] Foreign Application Priority Data Sept. 17, 1968 Germany ..P 17 77 180.1
[52] U.S. Cl ..72/l, 72/419, 83/409 [51] Int. Cl. ..B2ld 55/00, B2ld 43/00, 826d 7/06 [58} Field of Search ..72/1, 419; 83/409; 226/] l,
[56] References Cited UNITED STATES PATENTS 2,887,914 5/1959 Zeunert ..72/] 2,901,245 8/1959 Hensley ....83/409 X 3,330,175 7/ 1967 Bridges ....83/409 X 3,391,840 7/1968 King ....226/l1 3,429,491 2/1969 Windley ..226/|1 Primary Examiner-Charles W. Lanham Assistant Examiner-R. M. Rogers Attorney-Holman &. Stems ABSTRACT A longitudinal carriage drive for co-ordinates tables in machine tools for impelling the carriages on co-ordinates tables, particularly the longitudinal carriage, with the transverse carriage moving thereupon transversely to the longitudinal axis of the machine, and to the material to be punched held fast thereto, in which a power transmission by two screwthreaded spindles is provided to the left and right of the center of the machine, which receive their drive synchronously from a motor arranged at about the middle of the table.
3 Claims, 3 Drawing Figures PATENTEBMARZ] I972 3,650,133
sum 1 OF 3 lnrenfar:
6004 nm B/FEDa w PATENTEUMARZI I972 SHEET 2 OF 3 lnrenlonw 4 rat BREW 04 PATENTEUMMI I972 SHEET 3' [1F 3 lilllllll k lnren/ar: LUALTER BREDaw 37., k (T /M7 ATTDRA/EYS LONGITUDINAL CARRIAGE DRIVE FOR CO- ORDINATES TABLES IN MACHINE TOOLS, PARTICULARLY PUNCHING MACHINES BACKGROUND OF THE INVENTION This invention relates to the longitudinal carriage drive for coordinates tables in machine tools, particularly punching or stamping machines, for the transporting of the carriages on the coordinates tables, particularly of the longitudinal carriage, with the transverse carriage moving thereupon transversely to the longitudinal axis of the machine, and with the material to be punched or stamped held fast thereon, with power-transmission by screw-threaded spindles. The invention is particularly advantageous with revolving punches, with which the need arises to improve the accuracy of the positioning of the coordinates tables, and to provide the presumptions for the supervision of this accuracy.
SUMMARY OF THE INVENTION The invention consists in the feature that to the left and right of the center of the machine two threaded spindles are arranged, which receive their drive synchronously from a common driving motor arranged on about the center of the table. It has been found particularly advantageous in this case to employ ball rotary spindles, which, in consequence of the initial stress of the ball bearings, ensure running practically free from backlash in the transmission of the driving forces. The adoption of such spindles also has the advantage that the coefficient of friction of the driving spindle is completely invariable.
In a preferred form of construction of the invention, the driving motor and the power-transmitting means between this motor and the threaded spindles are arranged symmetrically about the Y-axis of the longitudinal carriage. Such an arrangement provides particularly advantageous presumptions for the accommodation of monitoring appliances, which already show any change of equilibrium between the drives, or even cut out the drive altogether. As power-transmitting means between the motor and the driving spindles, toothed belt gears are preferred. Such gears provide lightweight steel-armored expansion-free toothed belts, which transmit the driving forces positively and without slipping.
According to a further feature of the invention, with the toothed belts are associated electrical measured-value receivers, for instance electric generators, which, upon disturbance of the state of equilibrium, switch off the drive. It is also possible to associate light cabinets with the toothed belts. It is obvious that with the drive according to the invention, the driving means that are to meet the highest requirements as regards accuracy must remain protected against any disturbance in operation and against overstressing. The arrangement of the monitoring appliances is promoted by the same forces and the same speeds having to occur in each case at the same points in the symmetrically arranged driving system. Any change in the state of equilibrium gives rise to a response from the monitoring appliances, so that disturbances can be directly avoided. It is obvious that by the measures according to the invention, a considerable improvement in the accuracy of working of punching machines is also effected, which can thereby be employed in machining operations which require particularly high accuracy.
One constructional example of the invention is illustrated in the accompanying drawings, as applied to a revolving punch, and will now be further described. The invention is, however, also applicable to punching and stamping machines and other machine tools of a different construction.
In the accompanying drawings,
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a coordinates table in side elevation; FIG. 2 shows a plan view of the coordinates table; and FIG. 3 shows the coordinates table in front elevation.
DETAILED DESCRIPTION OF THE DRAWINGS Upon underpart 1 of the table are arranged, to right and left (FIG. 3), longitudinal girders 2 and 2' for the accommodation and guidance of a longitudinal carriage. To the longitudinal girders 2 and 2' are bolted guiding rails 3 and supporting rails 4, upon which the complete longitudinal carriage is guided and supported, respectively. The longitudinal carriage consists essentially of a cross girder 5, with a left-hand roller shoe 6 and a right-hand roller shoe 6', in which supporting rollers 7 and lateral guiding rollers 8 are journaled. To the underside of the roller shoes 6 and 6' are secured holders 9 and 9' for the accommodation of the ball rotary nuts of ball rotary spindles 10, serving advantageously as a drive, for driving the longitudinal carriage; and upon these roller shoes are secured supporting plates 11, 11 for the material to be punched. These bearing surfaces thus accompany the movement of the iongitudinal carriage.
The ball rotary spindles 10 are axially mounted in bearing shields 12 and 12 and bearings 13 and 13, which are connected fast, in front and behind, with the longitudinal girders 2 and 2' respectively.
Upon the cross girder 5 of the longitudinal carriage is secured a left-hand bearing 14 and a right-hand bearing 15, and also a motor casing 16, with a driving motor for a ball rotary spindle 17 of a transverse carriage 18. A ball rotary nut 19 on the spindle 17 is connected on the other side by its holder with the transverse carriage 18, and to the latter in turn is bolted a clamping rail 20. To this again workpiece-stretchers 21, three in number, for example, are displaceably secured. By these workpiece-stretchers is held material 22 to be punched, consisting of a plate, represented by dot-and-dash lines, for travelling between the upper and lower turntables of rotary punches. The axial positions of the bearings of these turntables are indicated at 23, and that of one of the tool stations at 24.
Between the lateral punching-material supporting plates 1 l and 11', and pivoted to the latter and moved therewith, are located transverse roller'guided punch-material supporting rails 25, which, upon the punched material being removed towards the left (see FIG. 1), are guided over a descending guiding curve 26 into an open space between the underpart l of the table and the transverse girder 5 of the longitudinal carriage and are there caught up. Guiding and connecting chains 27 for the punched-material rails 25 are pivotally connected by their right-hand ends 28 and 28' with the punched- material supporting plates 11 and 11, and by spring-equipped tension rods 29, in the bearing shields l2, 12', which are secured, under tension, to the front ends of the longitudinal girders 2 and 2'.
The longitudinal carriage drive by the ball rotary spindles 10 is effected completely without slip and with the spindles turning synchronously, by a driving motor 41, which is connected by a bearing shield 40 with the front wall of the underpart 1 of the table, with the aid of toothed belts 42, by way of corresponding toothed disc wheels 43. It will be seen that the power transmitting means between the motor 41 and the spindles are symmetrically arranged about Y-axis of the longitudinal carriage. In connection with the toothed belts 42 are arranged measured-value receivers, for instance electrical generators 44, or, optionally, light sensors 45, which respond to irregular running of the power-transmitting means, or to breakage of a toothed belt, and thereby preclude any injury to the drive, and to the guidance of the longitudinal carriage, by interrupting the drive.
What is claimed is:
l. A longitudinal carriage drive for coordinates tables in machine tools, particularly punching or stamping machines, for impelling the carriages on coordinates tables, particularly a longitudinal carriage, with a transverse carriage moving thereupon transversely to the longitudinal axis of the machine, and to material to be punched held fast thereto, with powerin the state of equilibrium, to deactivate the drive.
2. The longitudinal carriage drive as claimed in claim I, wherein said electrical measurement-value receivers are electric generators.
3. The longitudinal carriage drive as claimed in claim 1, wherein said electrical measurement-value receivers are light sensors.
II I I t t

Claims (3)

1. A longitudinal carriage drive for coordinates tables in machine tools, particularly punching or stamping machines, for impelling the carriages on coordinates tables, particularly a longitudinal carriage, with a transverse carriage moving thereupon transversely to the longitudinal axis of the machine, and to material to be punched held fast thereto, with powertransmission by screw-threaded spindles, the improvement including, to the left and right of the center of the machine, two threaded spindles, a motor arranged at approximately the middle of the table, toothed belt drives between the motor and the threaded spindles for transmitting power to the spindles symmetrically arranged about Y-axis of the longitudinal carriage and electrical measurement-value receivers operably related with the toothed belt drives and, operative upon a disturbance in the state of equilibrium, to deactivate the drive.
2. The longitudinal carriage drive as claimed in claim 1, wherein said electrical measurement-value receivers are electric generators.
3. The longitudinal carriage drive as claimed in claim 1, wherein said electrical measurement-value receivers are light sensors.
US3650133D 1968-09-17 1969-09-03 Longitudinal carriage drive for co-ordinates tables in machine tools, particularly punching machines Expired - Lifetime US3650133A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1777180A DE1777180C3 (en) 1968-09-17 1968-09-17 Drive device for longitudinal carriages on machine tools, in particular punching machines

Publications (1)

Publication Number Publication Date
US3650133A true US3650133A (en) 1972-03-21

Family

ID=5703077

Family Applications (1)

Application Number Title Priority Date Filing Date
US3650133D Expired - Lifetime US3650133A (en) 1968-09-17 1969-09-03 Longitudinal carriage drive for co-ordinates tables in machine tools, particularly punching machines

Country Status (3)

Country Link
US (1) US3650133A (en)
DE (1) DE1777180C3 (en)
GB (1) GB1251113A (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2315366A1 (en) * 1975-06-23 1977-01-21 So Fine Precision Sheet Metal MACHINE FOR MAKING HOLES
FR2403128A1 (en) * 1977-09-14 1979-04-13 Raskin Sa PROTECTION DEVICE FOR A SHEET SHEET OF A SHEET WORKING MACHINE
US4515050A (en) * 1982-11-09 1985-05-07 Hammerle Ag Maschinenfabrik Apparatus for feeding sheet metal plates to a sheet shear arrangement
US4548115A (en) * 1983-04-28 1985-10-22 Usm Corporation Positioning apparatus
US4669346A (en) * 1986-03-05 1987-06-02 Roper Whitney Co., Division Of Roper Industries, Inc. Machine with work positioning carriage
US4753099A (en) * 1985-09-18 1988-06-28 Trumpf Gmbh & Co. Bending press for sheet metal

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3203348A1 (en) * 1981-02-20 1982-09-09 Hauni-Werke Körber & Co KG, 2050 Hamburg Machine tool

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2887914A (en) * 1956-10-19 1959-05-26 Mannesmann Meer Ag Mandrel-protecting device for coldpilger rolling mills
US2901245A (en) * 1958-05-07 1959-08-25 Ty Sa Man Machine Company Plate positioning tables
US3330175A (en) * 1965-09-02 1967-07-11 Bridges Vernon Bruce Moveably supported cut off saw
US3391840A (en) * 1965-10-25 1968-07-09 Du Pont Yarn break detector and control circuit
US3429491A (en) * 1967-05-08 1969-02-25 Du Pont Break detector and shut down means

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2887914A (en) * 1956-10-19 1959-05-26 Mannesmann Meer Ag Mandrel-protecting device for coldpilger rolling mills
US2901245A (en) * 1958-05-07 1959-08-25 Ty Sa Man Machine Company Plate positioning tables
US3330175A (en) * 1965-09-02 1967-07-11 Bridges Vernon Bruce Moveably supported cut off saw
US3391840A (en) * 1965-10-25 1968-07-09 Du Pont Yarn break detector and control circuit
US3429491A (en) * 1967-05-08 1969-02-25 Du Pont Break detector and shut down means

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2315366A1 (en) * 1975-06-23 1977-01-21 So Fine Precision Sheet Metal MACHINE FOR MAKING HOLES
FR2403128A1 (en) * 1977-09-14 1979-04-13 Raskin Sa PROTECTION DEVICE FOR A SHEET SHEET OF A SHEET WORKING MACHINE
US4515050A (en) * 1982-11-09 1985-05-07 Hammerle Ag Maschinenfabrik Apparatus for feeding sheet metal plates to a sheet shear arrangement
US4548115A (en) * 1983-04-28 1985-10-22 Usm Corporation Positioning apparatus
US4753099A (en) * 1985-09-18 1988-06-28 Trumpf Gmbh & Co. Bending press for sheet metal
US4669346A (en) * 1986-03-05 1987-06-02 Roper Whitney Co., Division Of Roper Industries, Inc. Machine with work positioning carriage

Also Published As

Publication number Publication date
GB1251113A (en) 1971-10-27
DE1777180C3 (en) 1975-02-20
DE1777180B2 (en) 1974-07-11
DE1777180A1 (en) 1971-08-26

Similar Documents

Publication Publication Date Title
EP0205988B1 (en) Improvements in machine tools
US3650133A (en) Longitudinal carriage drive for co-ordinates tables in machine tools, particularly punching machines
ES8703807A1 (en) Plant for sorting items, with self driven carriages
CN201020540Y (en) Digital control underfloor wheel pair lathe
EP0318966A3 (en) Machine for processing surfaces with a device for positioning work tools
US3136182A (en) Replacement of roll stands in rolling mills
CN212374338U (en) 180-degree turnover conveying equipment for heavy workpieces
US2083682A (en) Carriage mounting for grinding machines
CN108856734A (en) A kind of automatic lathe for cylindrical work processing
ES394748A1 (en) Indexing system for shears, presses and the like
CN114851284B (en) High-precision automatic cutting machine
GB2149695A (en) A longitudinal slide feed device for a pair of machine tool slides
CN206067012U (en) A kind of quick die change device of great tonnage hydraulic machine
US5779025A (en) Three-dimensional gripper rail drive apparatus
CN107282946A (en) A kind of device processed for automotive casting part
US3586174A (en) Parts transfer mechanism
US2308985A (en) Centering device
US2959992A (en) Master control device for rolling mills and the like
US3457834A (en) Weld flash trimmer
GB1144860A (en) Improvements in table assembly
EP0677435A2 (en) Trolley for transporting workpieces
CN215615197U (en) Direct-drive drilling machine structure for factory production and processing
GB874597A (en) Improvements in or relating to punching machines
SU141400A1 (en) Repair attachment to the machine (conveyor) for grinding and polishing glass simultaneously on both sides
CN209953707U (en) Shaft type abrasion-proof device