GB2118101A - Improvements in and relating to daisy wheels - Google Patents
Improvements in and relating to daisy wheels Download PDFInfo
- Publication number
- GB2118101A GB2118101A GB08228684A GB8228684A GB2118101A GB 2118101 A GB2118101 A GB 2118101A GB 08228684 A GB08228684 A GB 08228684A GB 8228684 A GB8228684 A GB 8228684A GB 2118101 A GB2118101 A GB 2118101A
- Authority
- GB
- United Kingdom
- Prior art keywords
- spokes
- wheel
- feed ring
- outer ends
- radially outer
- 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.)
- Withdrawn
Links
- 241000723353 Chrysanthemum Species 0.000 title claims abstract description 26
- 235000005633 Chrysanthemum balsamita Nutrition 0.000 title claims abstract description 26
- 239000000463 material Substances 0.000 claims abstract description 15
- 238000002347 injection Methods 0.000 claims abstract description 12
- 239000007924 injection Substances 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims description 14
- 238000000465 moulding Methods 0.000 claims description 13
- 238000001746 injection moulding Methods 0.000 claims description 6
- 238000005520 cutting process Methods 0.000 claims description 4
- 229920003023 plastic Polymers 0.000 abstract description 3
- 239000004033 plastic Substances 0.000 abstract description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000036244 malformation Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/0046—Details relating to the filling pattern or flow paths or flow characteristics of moulding material in the mould cavity
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J1/00—Typewriters or selective printing mechanisms characterised by the mounting, arrangement or disposition of the types or dies
- B41J1/22—Typewriters or selective printing mechanisms characterised by the mounting, arrangement or disposition of the types or dies with types or dies mounted on carriers rotatable for selection
- B41J1/24—Typewriters or selective printing mechanisms characterised by the mounting, arrangement or disposition of the types or dies with types or dies mounted on carriers rotatable for selection the plane of the type or die face being perpendicular to the axis of rotation
- B41J1/28—Carriers stationary for impression, e.g. with the types or dies not moving relative to the carriers
- B41J1/30—Carriers stationary for impression, e.g. with the types or dies not moving relative to the carriers with the types or dies moving relative to the carriers or mounted on flexible carriers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/0025—Preventing defects on the moulded article, e.g. weld lines, shrinkage marks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/32—Wheels, pinions, pulleys, castors or rollers, Rims
- B29L2031/322—Wheels, pinions, pulleys, castors or rollers, Rims made wholly of plastics
Abstract
A daisy wheel 1 is injection moulded in a plastics material which flows into a feed ring 8 extending around the wheel and then from the ring 8 through the spokes 3 of the daisy wheel from the radially outer ends thereof on which the print characters 4 are provided towards the hub 2 of the daisy wheel. The ring 8 is subsequently removed to leave the radially outer ends of the spokes free. <IMAGE>
Description
SPECIFICATION
Improvements in and relating to daisy wheels
This invention relates to daisy wheels and a method of producing the same.
A daisy wheel is a printing element used in typewriters and other printing machines which comprises a hub having radially outwardly extending spokes provided with print characters at their radially outer ends, which ends are free so that a printing impression may occur on deflection of the spokes from the plane in which they are disposed.
Exacting requirements are set for daisy wheels.
On the one hand they must consist of a material which is sufficiently resilient to withstand the necessary deformation during an impression action without breakage occurring. On the other hand, the characters, in particular, must have a hardness which ensures stability of shape even over a large number of strokes.
According to the DE - OS 28 18 861, a method is known wherein the injection process is carried out with the moulding material flowing outwards from the hub to the free ends of the spokes. This known method has the disadvantage that air occlusions (small air bubbles) can occur at the free ends of the spokes on which the characters are disposed. In addition, the pressure of the moulding material generally decreases the further away the ends of the spokes are from the sprue opening at the hub giving rise to possible malformation of the characters.
It is an object of the invention to provide a method which enables the characters to be more precisely formed and so that occurrence of air occlusions in the free ends of the spokes can be reduced.
According to the present invention there is provided a method of producing a daisy wheel comprising a hub having radially outwardly extending spokes provided with print characters at their radially outer ends, comprising injection moulding the wheel with moulding material which flows into a feed ring extending around the wheel and then from the ring through the spokes from the radially outer ends thereof towards the hub, and thereafter separating the feed ring from the spokes to leave the radially outer ends of the spokes free.
It has bsen found that in carrying out a method in accordance with the present invention any air inclusions tend to be displaced inwards into the hub of the wheel where their presence is less critical than in the spokes because of the hub's more robust construction. Experiments have also shown that considerably harder characters are formed using the present invention resulting in a longer life for the daisy wheel.
Preferably the feed ring is parted-off by means of a cutting tool which may for example comprise a cylindrical cutter. The material of the ring, can, of course, be reused.
Preferably the feed ring has a cross-sectional area of from ten to twelve times the crosssectional area of a spoke of the wheel. This enables rapid distribution of the moulding material inside the mould cavity defining the ring and high pressure distribution of the moulding material within the mould cavities defining the spokes.
In a preferred embodiment, the moulding material flows from said feed ring to the radially outer ends of said spokes through respective nozzles which provide connections between the feed ring and the spokes, such that at the side at which the characters are disposed on the spokes the connections each have a surface which lies in substantially the same plane as the surface of the spoke connected thereto. This has the advantage that the sides of the spokes on which the characters are disposed remain free from any residues of the connections.
The invention also includes an injection moulded daisy wheel comprising a hub having radially outwardly extending spokes provided with print characters at their radially outer ends, which ends are connected to a feed ring which is adapted to be removed from the daisy wheel to leave the radially outer ends of the spokes free.
In order that the invention may be well understood, the presently preferred embodiment thereof, which is given by way of example only, will now be described, reference being had to the accompanying drawings, in which:
Figure 1 is a plan view of an injection moulding of a daisy wheel with the feed ring still attached and with some of the spokes omitted for the sake of clarity; and
Figure 2 is a semi-axial cross-section of the moulding shown in Figure 1 to a larger scale.
In the drawings there is shown a plastics injection moulding of a daisy wheel 1 comprising a hub 2 having radially outwardly extending spokes
3 provided with print characters 4 at their radially outer ends which ends are free in the finished daisy wheel but are illustrated still connected to via connections 9 to a feed ring 8 which extends around the daisy wheel and which has a single sprue 7.
During injection moulding, the plastics moulding material flows from the sprue in the directions A and B around the ring 8. As shown in
Figure 1, the two flows of material meet in the
upper region C of the ring 8. Thereafter, the
moulding material is forced radially inwards
through injection nozzles forming connections 9, to form the characters and a possible preceding centring wedge, designated by 10 in Figure 2 at the back of the spoke, in the moulding tool. It can clearly be seen that any air contained in the
moulding tool is displaced to the middle towards
the hub 2 by this method of production. It is also
clear that the injection pressure is greater in the
region of the characters 4 than in the region of the
hub 2. As a result, a precise formation of the
characters is achieved.
After the injection moulding of the daisy wheel
1 together with the ring 8 is ejected from the
mould, the ring 8 is separated from the spokes 3
by parting-off using a cutting tool, for example a cylindrical cutter, substantially in the region of the plane D shown in chain line in Figure 2 to leave the radially outer ends of the spokes free.
It has proved advisable to select the crosssectional area of the ring 8 substantially so that it corresponds to 10 to 12 times the cross-sectional of a type spoke. It is also advisable for the ring 8 to have a height H which is greater than the thickness S of the hub 2. In order to increase the injection pressure during the flow of material at the radially outer ends of the spokes 3, it is advisable to make the injection nozzles which form the connections 9 tapered in cross-section. It is, however, advisable to construct the injection nozzles so that, at the side at which the characters 4 are disposed, the connections 9 form a surface 11 which lies substantially on the same plane as the surface 12 of the spokes 3. The tapered construction of the injection nozzles has the advantage that an increase in the injection pressure results during the formation of the characters 4. In addition, a slight cutting pressure is sufficient at the point at which the parting-off from the spokes 3 is effected (plane D). As a result, damage to the daisy wheel 1, the spokes 3 or the characters 4 during parting-off is largely excluded.
In the middle of the hub 2 there may be a metal ring 5 by means of which the daisy wheel 1 can be mounted on a shaft. Usually, such daisy wheels are provided with an entrainment opening 6 through which an entrainment finger projects in order to achieve a connection of the daisy wheel to a shaft so that it is held against rotation in relation thereto.
Claims (8)
1. A method of producing a daisy wheel comprising a hub having radially outwardly extending spokes provided with print characters at their radially outer ends, comprising injection moulding the wheel with moulding material which flows into a feed ring extending around the wheel and then from the ring through the spokes from the radially outer ends thereof towards the hub, and thereafter separating the feed ring from the spokes to leave the radially outer ends of the spokes free.
2. A method as claimed in claim 1 ,wherein the feed ring is parted-off by means of a cutting tool.
3. A method as claimed in claim 1 or 2, wherein the feed ring has a cross-sectional area of from ten to twelve times the cross-sectional area of a spoke of the wheel.
4. A method as claimed in claim 1 , 2 or 3, wherein the feed ring has an axial depth which is greater than the axial depth of the hub.
5. A method as claimed in any one of the preceding claims, wherein the moulding material flows from said feed ring to the radially outer ends of said spokes through respective nozzles which provide connections between the feed ring and the spokes, such that at the side at which the characters are disposed on the spokes the connections each have a surface which lies in substantially the same plane as the surface of the spoke connected thereto.
6. An injection moulded daisy wheel comprising a hub having radially outwardly extending spokes provided with print characters at their radially outer ends, which ends are connected to a feed ring which is adapted to be removed from the daisy wheel to leave the radially outer ends of the spokes free.
7. A method of producing a daisy wheel substantially as herein described with reference to the accompanying drawing.
8. An injection moulded daisy wheel with a feed ring connected thereto, substantially as herein described with reference to the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3212318A DE3212318C1 (en) | 1982-04-02 | 1982-04-02 | Process for the production of one-piece type plate blanks for typewriters or similar machines and type plate blanks produced by this method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2118101A true GB2118101A (en) | 1983-10-26 |
Family
ID=6160087
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08228684A Withdrawn GB2118101A (en) | 1982-04-02 | 1982-10-07 | Improvements in and relating to daisy wheels |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS58173663A (en) |
| DE (1) | DE3212318C1 (en) |
| FR (1) | FR2524388A1 (en) |
| GB (1) | GB2118101A (en) |
| IT (1) | IT1152321B (en) |
| SE (1) | SE8203978L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998004400A1 (en) * | 1996-07-31 | 1998-02-05 | Rolf Kistner | Tread roller |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3613842A1 (en) * | 1986-04-24 | 1987-10-29 | Reinhold Langbein | METHOD AND INJECTION MOLDING TOOL FOR PRODUCING A ROTOR FOR ELECTRIC MOTORS |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1480362A (en) * | 1973-11-08 | 1977-07-20 | Pitney Bowes Inc | Printing disc assembly and method for making same |
| GB1562218A (en) * | 1975-09-12 | 1980-03-05 | Ricoh Kk | Serial printing apparatus |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL6512032A (en) * | 1965-09-15 | 1967-03-16 | ||
| SE7702019L (en) * | 1976-03-08 | 1977-09-09 | Wang Laboratories | TYPE WHEELS |
| JPS5680467A (en) * | 1979-12-06 | 1981-07-01 | Sumitomo Bakelite Co Ltd | Manufacture of plastic type |
-
1982
- 1982-04-02 DE DE3212318A patent/DE3212318C1/en not_active Expired
- 1982-06-28 SE SE8203978A patent/SE8203978L/en not_active Application Discontinuation
- 1982-08-04 IT IT22729/82A patent/IT1152321B/en active
- 1982-08-23 JP JP57144899A patent/JPS58173663A/en active Pending
- 1982-08-31 FR FR8214871A patent/FR2524388A1/en not_active Withdrawn
- 1982-10-07 GB GB08228684A patent/GB2118101A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1480362A (en) * | 1973-11-08 | 1977-07-20 | Pitney Bowes Inc | Printing disc assembly and method for making same |
| GB1562218A (en) * | 1975-09-12 | 1980-03-05 | Ricoh Kk | Serial printing apparatus |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998004400A1 (en) * | 1996-07-31 | 1998-02-05 | Rolf Kistner | Tread roller |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2524388A1 (en) | 1983-10-07 |
| DE3212318C1 (en) | 1983-07-21 |
| IT8222729A0 (en) | 1982-08-04 |
| JPS58173663A (en) | 1983-10-12 |
| SE8203978L (en) | 1983-10-03 |
| IT1152321B (en) | 1986-12-31 |
| SE8203978D0 (en) | 1982-06-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |