U.S. patent application number 13/867641 was filed with the patent office on 2013-09-12 for mechanism and system for clamping.
This patent application is currently assigned to ATS AUTOMATION TOOLING SYSTEMS INC.. The applicant listed for this patent is ATS AUTOMATION TOOLING SYSTEMS INC.. Invention is credited to Robert Donald ECOB.
Application Number | 20130236586 13/867641 |
Document ID | / |
Family ID | 44656789 |
Filed Date | 2013-09-12 |
United States Patent
Application |
20130236586 |
Kind Code |
A1 |
ECOB; Robert Donald |
September 12, 2013 |
MECHANISM AND SYSTEM FOR CLAMPING
Abstract
A clamping mechanism having: a drive; a shaft connected to the
drive; an eccentric hub that is driven to rotate by the shaft; a
fixed support structure that supports the eccentric hub such that
the eccentric hub can rotate; and a moving support structure that
is connected to the eccentric hub such that the moving support
structure is driven substantially linearly based on rotational
motion of the eccentric hub and serves to clamp an object between
the moving support structure and a fixed structure adjacent to the
moving support structure. A clamping system is provided having, a
single drive; a shaft connected to the drive; and a plurality of
clamping mechanisms.
Inventors: |
ECOB; Robert Donald;
(Cambridge, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ATS AUTOMATION TOOLING SYSTEMS INC. |
Cambridge |
|
CA |
|
|
Assignee: |
ATS AUTOMATION TOOLING SYSTEMS
INC.
Cambridge
CA
|
Family ID: |
44656789 |
Appl. No.: |
13/867641 |
Filed: |
April 22, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13074232 |
Mar 29, 2011 |
8425219 |
|
|
13867641 |
|
|
|
|
61318729 |
Mar 29, 2010 |
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Current U.S.
Class: |
425/170 ;
425/451.4 |
Current CPC
Class: |
B29C 45/66 20130101;
B29C 33/26 20130101 |
Class at
Publication: |
425/170 ;
425/451.4 |
International
Class: |
B29C 33/26 20060101
B29C033/26 |
Claims
1. A clamping mechanism comprising: a drive; a shaft connected to
the drive; an eccentric hub that is driven to rotate by the shaft;
a support structure that supports the eccentric hub such that the
eccentric hub can rotate; and a moving support structure that is
connected to the eccentric hub such that the moving support
structure is driven substantially linearly based on rotational
motion of the eccentric hub toward a second structure adjacent to
the moving support structure.
2. The clamping mechanism of claim 1, wherein the eccentric hub is
driven by a shaft through an angle of less than approximately 180
degrees.
3. The clamping mechanism of claim 2, wherein the eccentric hub of
the clamping mechanism is driven by the shaft by a drive key
connecting the shaft to the eccentric hub.
4. The clamping mechanism of claim 1 wherein the moving support
structure of the clamping mechanism supports a first portion of a
mold and the second structure adjacent the moving support structure
is a second portion of the mold.
5. The claiming mechanism of claim 1 further comprising a load cell
provided to the eccentric hub to monitor the pressure applied.
6. A clamping system comprising: a single drive; a shaft connected
to the drive; a plurality of clamping mechanisms, each clamping
mechanism comprising: an eccentric hub that is driven to rotate by
the shaft; a support structure that supports the eccentric hub such
that the eccentric hub can rotate; and a moving support structure
that is connected to the eccentric hub such that the moving support
structure is driven substantially linearly based on rotational
motion of the eccentric hub, wherein the plurality of clamping
mechanisms support a platen and the plurality of clamping
mechanisms serve to move the platen toward a second structure
adjacent to the platen when the eccentric hub is rotated.
7. The clamping system of claim 6, wherein each eccentric hub of
the plurality of clamping mechanisms is driven by the shaft through
an angle of less than approximately 180 degrees.
8. The clamping system of claim 7 wherein each eccentric hub of the
plurality of clamping mechanisms is driven by the shaft by a drive
key connecting the shaft to each eccentric hub.
9. The clamping system of claim 6 wherein the moving support
structure supports a first portion of a mold and the second
structure adjacent the moving support structure is a second portion
of the mold.
10. The clamping system of claim 6 further comprising a load cell
provided to at least one of the eccentric hubs to monitor the
pressure applied.
Description
RELATED APPLICATIONS
[0001] This application is a Continuation of U.S. patent
application Ser. No. 13/074,232, filed Mar. 29, 2011, which claims
the benefit of priority of U.S. Provisional Patent Application No.
61/318,729 filed Mar. 29, 2010, which are both incorporated herein
by reference in their entirety.
FIELD
[0002] The present document relates generally to a clamping
mechanism. More particularly, the present document relates to a
clamping system and mechanism for opening, closing and clamping
presses for molding.
BACKGROUND
[0003] Mechanical molding presses are commonplace in the
manufacturing industry. In order to lock these presses in position,
it is necessary to provide a clamping system or mechanism to keep
the parts of the mold in position while plastic or the like is
injected under pressure. Often these clamping mechanisms are large
and complex and, like many mechanical systems, may require
externally applied lubricant to keep moving parts operating
smoothly.
[0004] In some molding applications, additional consideration may
need to be given to the loads, space constraints and clean room
requirements, for example, if the molding is for medical
applications or the like, where the potential for contaminant
lubricant leakage is possible. In these environments, conventional
hydraulic or toggle clamping mechanisms may not be appropriate.
Further, electro-mechanical devices such as servo drives are
generally not capable of delivering the repetitive loads and forces
often required for plastic molding and typically are quite large
and/or produce significant amounts of heat during operation.
SUMMARY
[0005] Thus, there is a need for a clamping apparatus that is
simple, and a clamping system with efficient means to open, close
and mechanically clamp a molding press. There is a further need for
a clamping mechanism and system to be used in a clean-room
environment, for injection and compression molding, where it would
be advantageous if the clamping system and mechanism used a minimal
amount or no external lubrication.
[0006] In one aspect, there is provided a clamping mechanism
including: a drive; a shaft connected to the drive; an eccentric
hub that is driven to rotate by the shaft; a fixed support
structure that supports the eccentric hub such that the eccentric
hub can rotate; and a moving support structure that is connected to
the eccentric hub such that the moving support structure is driven
substantially linearly based on rotational motion of the eccentric
hub and serves to clamp an object between the moving support
structure and a fixed structure adjacent to the moving support
structure. This clamping mechanism is intended to be simple and
operates with little or no external lubricants.
[0007] In a further aspect, a clamping mechanism is provided
wherein the eccentric hub may be driven by a shaft through an angle
of less than approximately 180 degrees. The eccentric hub of the
clamping mechanism may be driven by the shaft by a drive key
connecting the shaft to the eccentric hub.
[0008] In another aspect, a moving support structure of the
clamping mechanism may support a first portion of a mold and the
fixed structure adjacent the moving support structure may be a
second portion of the mold. In one case, the clamping mechanism may
further include a load cell provided to the eccentric hub to
monitor the pressure applied.
[0009] In a further aspect, there is provided a clamping system
including: a single drive; a shaft connected to the drive; a
plurality of clamping mechanisms, each clamping mechanism
comprising: an eccentric hub that is driven to rotate by the shaft;
a fixed support structure that supports the eccentric hub such that
the eccentric hub can rotate; a moving structure that is connected
to the eccentric hub such that the moving support structure is
driven substantially linearly based on rotational motion of the
eccentric hub wherein the plurality of clamping mechanisms support
a platen and the plurality of clamping mechanisms serve to clamp an
object between the platen and a fixed structure adjacent to the
platen when the eccentric hub is created.
[0010] In another aspect, a clamping system is provided wherein the
eccentric hub of the clamping mechanism may be driven by the shaft
through an angle of less than approximately 180 degrees. The
clamping system may further have an eccentric hub of a clamping
mechanism driven by a shaft by a drive key connecting the shaft to
the eccentric hub.
[0011] In another aspect, a clamping system may further include a
moving support structure that may support a first portion of a mold
and a fixed structure adjacent to the moving support structure that
may be a second portion of the mold. The clamping system may
further include a load cell provided to the eccentric hub to
monitor the pressure applied.
[0012] Other aspects and features will become apparent to those
ordinarily skilled in the art upon review of the following
description of specific embodiments in conjunction with the
accompanying figures.
BRIEF DESCRIPTION OF FIGURES
[0013] Embodiments will now be described, by way of example only,
with reference to the attached figures, wherein:
[0014] FIG. 1 illustrates a clamping system with two clamping
mechanisms according to one embodiment;
[0015] FIG. 2 illustrates the clamping system in use with a molding
press;
[0016] FIG. 3A illustrates a clamping mechanism is a locked/clamped
position;
[0017] FIG. 3B illustrates the clamping mechanism in an
unlocked/unclamped position; and
[0018] FIG. 4 illustrates a clamping system in block diagram
form.
DETAILED DESCRIPTION
[0019] FIG. 1 shows a clamping system 100 according to an
embodiment herein. The clamping system 100 includes at least one
clamping mechanism 105 (two are illustrated), a drive shaft 110
interacting with the clamping mechanism 105 to drive the clamping
mechanism 105 and a drive (not shown) for driving the drive shaft
110. In a case where the drive shaft 110 may extend over some
distance, the drive shaft 110 may be supported by a spacer 115 and
spacer bearing 120.
[0020] FIG. 2 shows the use of the clamping system 100 with an
injection molding press 200. The clamping system 100 is provided
between a fixed platen 205 and a moving platen 210. A lower mold
portion 215 is mounted on the moving platen 210. The clamping
system 100 can be operated to move the moving platen 210 and lower
mold portion 215 up and down in relation to an adjacent upper mold
portion (not shown) as shown by arrow 220 in FIG. 2 and clamp the
lower mold portion 215 in place against the upper mold portion.
[0021] FIGS. 3A and 3B illustrate the clamping mechanism 105 in
clamped and unclamped positions, respectively. The clamping
mechanism 105 includes a fixed pillow block 125 to mount the
clamping mechanism on the fixed platen 205. The fixed pillow block
125 supports the drive shaft 110 via a shaft bearing 130. The drive
shaft 110 is keyed to a drive key 135 that supports and drives an
eccentric hub 140. The drive key 135 may be a precision spline
between the eccentric hub 140 and shaft 110, which allows for a
direct drive. The eccentric hub 140 is attached to a moving pillow
block 145 via a pillow bearing 150 such that the moving pillow
block 145 can rotate relative to the eccentric hub 140. The moving
pillow block 145 can then be attached to the moving platen 210. In
some embodiments, a load cell 155 may be provided between the
moving pillow block 145 and the moving platen 210. The eccentric
hub 140 is configured such that a rotation of the eccentric hub 140
causes substantially linear movement of the moving pillow block 145
in a vertical direction.
[0022] Although the present embodiment illustrates vertical
movement, it will be understood that there may also be situations
involving non-vertical movement in which a similar mechanism may be
utilized. Further, other clamping mechanisms that include an
eccentric hub that is driven to rotate by a shaft and including a
moving support structure such that the moving support structure is
driven substantially linearly based on rotational motion of the
eccentric hub may be possible. The present disclosure describes a
sample embodiment that may be preferred due to its simplicity.
[0023] In operation, the clamping mechanism 105 is initially in a
lowered position as shown in FIG. 3B. In this lowered position, the
eccentric hub 140 is positioned such that the moving pillow block
145 is lowered. The drive shaft 110 then rotates and causes the
drive key 135 to drive the eccentric hub 140 to rotate such that
the moving pillow block 145 is moved linearly upward by the pillow
bearing 150. The drive shaft 110 continues driving until the moving
pillow block 145 and the related lower mold portion 215 is placed
with sufficient pressure against the upper mold portion. The drive
shaft 110 then maintains the pressure on the moving pillow block
145. When the axes of the drive shaft 110, eccentric hub 140 and
pillow bearing 150 are substantially aligned normal to the
direction of clamp, the clamping mechanism 105 creates a
mechanically locked condition, which may be effectively as strong
as the compressive structural capabilities of the weakest member of
the clamping mechanism 105. The nature of the elements of the
clamping mechanism acting in a single central vector results in a
solid mechanical lock condition, which may only be released by
rotating the eccentric hub 140, similar to the locked condition of
a human elbow when the arm is fully extended. No other lock element
should be necessary; however, the rotation of the drive
shaft/eccentric hub may also be locked, if desired, to resist
excessive vibration, although this generally would not occur in a
rigid/solid press.
[0024] The eccentric hub 140 and other elements of the clamping
mechanism 105 may be formed of steel or other appropriate material
to provide sufficient structural strength.
[0025] The clamping mechanism 105 is somewhat similar to a
crankshaft and connecting rod assembly (not shown); however, the
eccentric movement of the clamping mechanism 105 will generally not
involve a full revolution. The clamping mechanism 105, and in
particular the eccentric hub 140, may only rotate back and forth
about a given angle, and, in one particular case, the angle may be
less than 180 degrees. In another case, the angle may be less than
approximately 130 degrees.
[0026] The clamping system 100 may include a single clamping
mechanism 105 or may include a plurality of clamping mechanisms 105
(two are shown in FIG. 1). The clamping mechanisms 105 are intended
to be positioned normal and opposite the mold portions.
[0027] The clamping system 100 and clamping mechanism 105 may be
harmonically driven and balanced by either a single drive (as
indicated in FIG. 1) or a plurality of drives, although the use of
a single drive can be more space efficient and may require less
control equipment (not shown) in order to synchronize the clamping
mechanisms 105. The drive may include hydraulic cylinders,
servo-drives, or other suitable systems. It is anticipated that the
clamping system 100 herein will be space efficient while still
providing adequate clamping forces for loads up to or in excess of
approximately fifty tons per mold, although this is only an
estimate. It will be understood that the actual load constraints
will generally be determined by the physical strength of the
materials, load capability of the bearings and the torque required
to preload the elements into a state of mechanical lock.
[0028] In the embodiments herein, the clamping mechanism 105
requires relatively few mechanical parts, and will typically
require less or no external lubrication, since all elements are
intended to move on sealed bearings or bushings. The clamping
system 100 is also intended to be space efficient and effective for
molds that are horizontally wide or situations involving a
plurality of side-by-side molds mounted to a single set of platens.
As shown in FIG. 1, additional shaft supports (such as the spacer
115 and spacer bearing 120) may be added throughout the mid-span to
counteract any drive shaft 110 whip. The clamping mechanisms 105
are intended to experience reduced wear over time due to the use of
sealed bearings and bushings, thus reducing any variance in
movements due to wear. The bearing components (spacer bearings 115,
shaft bearing 130, pillow bearing 150) may be standard commercially
available needle roller bearings or similar and the clamping system
100 can be configured such that the bearing components are easily
replaceable to reduce overall maintenance costs.
[0029] The clamping system 100 may allow for the velocity of the
clamping mechanisms 105 (and related press platen and mold) to
rapidly decrease from the start of cycle to full clamp, giving a
quick but gentle action to the mold. Likewise on the opening
stroke, the movement of the clamping system 100 may accelerate more
as the stroke is increased until a full-open position is
reached.
[0030] As the clamping system 100 uses an eccentric hub 140, the
generated loads may typically be lighter until the angle of the
connecting member approaches a few degrees off a straight line as
shown in FIG. 3A. The increase in load can therefore be inversely
proportional to the velocity of action described above. This
feature may be advantageous for overcoming large quick-intensity
internal mold loads due to sudden injection or compression of
material being molded into mold cavities and help to avoid the mold
faces (i.e. first and second portions of the mold) "cracking" open
momentarily during injection and packing pressures. This feature is
intended to reduce the flashing on molded parts that can occur when
the mold portions part during injection pressure.
[0031] As noted above, in some embodiments, a load cell or cells
155 may be attached to each clamping mechanism 105 in order to
provide feedback of real-time clamping loads per angle of the
eccentric hub 140 to a processor 160, as illustrated in FIG. 4.
This feedback may be used to provide mold-safety/protection in the
event of a physical interference between the faces of the mold, or
any other inhibitor to resistance-free closing. The mold press
controls 165 may interact with the processor 160 to use the
feedback from the load cell 155. The feedback may be used to
prevent press and mold damage, and for real time monitoring of
loads during the molding cycle and amending the output 170. For
applications where more than one clamping mechanism 105 is used,
for example, for wide spacing, the load cells 155 may also be used
for comparative force data collection and real-time monitoring. For
example, if a cavity opposite one eccentric hub or clamping
mechanism was not pressurized the same as an opposing cavity
opposite another clamping mechanism, this data can be reported and
acted on in real time.
[0032] In the preceding description, for purposes of explanation,
numerous details are set forth in order to provide a thorough
understanding of the embodiments. However, it will be apparent to
one skilled in the art that these specific details may not be
required in order to practice the embodiments. In other instances,
well-known structures may be shown in simplified or block diagram
form in order not to obscure the embodiments.
[0033] The above-described embodiments are intended to be examples
only. Those of skill in the art can effect alterations,
modifications and variations to the particular embodiments without
departing from the scope, which is defined solely by the claims
appended hereto.
[0034] Embodiments of the disclosure can be represented as a
computer program product stored in a machine-readable medium (also
referred to as a computer-readable medium, a processor-readable
medium, or a computer usable medium having a computer-readable
program code embodied therein). The machine-readable medium can be
any suitable tangible, non-transitory medium, including magnetic,
optical, or electrical storage medium including a diskette, compact
disk read only memory (CD-ROM), memory device (volatile or
non-volatile), or similar storage mechanism. The machine-readable
medium can contain various sets of instructions, code sequences,
configuration information, or other data, which, when executed,
cause a processor to perform steps in a method according to an
embodiment of the disclosure. Those of ordinary skill in the art
will appreciate that other instructions and operations necessary to
implement the described implementations can also be stored on the
machine-readable medium. The instructions stored on the
machine-readable medium can be executed by a processor or other
suitable processing device, and can interface with circuitry to
perform the described tasks.
* * * * *